High risk group for screening. Biochemical screening - what is this test? What is prenatal diagnosis

Prenatal screening examination of the first trimester consists of two procedures: ultrasound diagnostics and blood tests for the possibility of genetic abnormalities of the fetus. There is nothing wrong with these events. The data obtained by performing an ultrasound procedure and a blood test is compared with the norm for this period, which allows you to confirm the good or bad condition of the fetus and determine the quality of the gestation process.

For the expectant mother, the main task is to maintain a good psycho-emotional and physical condition. It is also important to follow the instructions of the obstetrician-gynecologist leading the pregnancy.

Ultrasound is only one study of the screening complex. To obtain complete information about the health of the baby, the doctor must check the blood of the future woman in labor for hormones, evaluate the result of a general analysis of urine and blood

Standards for ultrasound diagnostics I screening

In the process of carrying out the first prenatal screening in the first trimester, the ultrasound diagnostics doctor pays special attention to the anatomical structures of the fetus, specifies the gestational age (gestation) on the basis of fetometric indicators, comparing it with the norm. The most carefully evaluated criterion is the thickness of the collar space (TVP), because this is one of the main diagnostically significant parameters, which makes it possible to identify genetic diseases of the fetus during the first ultrasound procedure. In chromosomal abnormalities, the collar space is usually enlarged. Weekly TVP rates are shown in the table:

10	1,5 – 2,2
11	1,6 – 2,4
12	1,6 – 2,5
13	1,7 – 2,7

When conducting ultrasound screening of the first trimester, the doctor pays special attention to the structure of the facial structures of the fetal skull, the presence and parameters of the nasal bone. For a 10-week period, it is already quite clearly defined. At 12 weeks, its size in 98% of healthy fetuses is from 2 to 3 mm. The maxillary bone size of the baby is assessed and compared with the norm. a noticeable decrease in the parameters of the jaw in relation to the norm indicates trisomy.

On ultrasound 1 screening, the fetal heart rate (heart rate) is recorded and is also compared with the norm. The indicator depends on the gestational age. Weekly heart rate rates are shown in the table:

10	161-179
11	153-177
12	150-174
13	147-171

The main fetometric indicators at this stage during the ultrasound procedure are the coccygeal-parietal (CTE) and biparietal (BPR) sizes. Their norms are given in the table:

10	31-41	14
11	42-49	13-21
12	51-62	18-24
13	63-74	20-28
14	63-89	23-31

The first screening provides for an ultrasound assessment of blood flow in the venous (Arantia) duct, since in 80% of cases of its violation, the child is diagnosed with Down syndrome. And only 5% of genetically normal fetuses show such changes.

Starting from the 11th week, it becomes possible to visually recognize the bladder during ultrasound. At the 12th week, at the first ultrasound screening, its volume is assessed, since an increase in the size of the bladder is another evidence of the threat of the development of trisomy (Down) syndrome.

It is best to donate blood for biochemistry on the same day as the ultrasound screening. Although this is not a requirement. Blood sampling is carried out on an empty stomach. The analysis of biochemical parameters, which is carried out in the first trimester, is aimed at identifying the degree of threat of the occurrence of genetic diseases in the fetus. For this, the following hormones and proteins are determined:

pregnancy-associated plasma protein-A (PAPP-A);
free hCG (beta component).

These indicators depend on the week of pregnancy. The range of possible values is quite wide and correlates with the ethno-content of the region. In relation to the average-normal value for a given region, the level of indicators fluctuates within the following limits: 0.5-2.2 MoM. When calculating the threat and decoding the data, not just the average value is taken for analysis, all possible corrections for the anamnestic data of the expectant mother are taken into account. This adjusted MoM allows a more complete determination of the threat of the development of genetic pathology of the fetus.

A blood test for hormones is necessarily carried out on an empty stomach and is often prescribed on the same day as an ultrasound scan. Due to the presence of standards for the hormonal characteristics of the blood, the doctor can compare the test results of a pregnant woman with the norms, identify a lack or excess of certain hormones hCG: an assessment of risk values

In terms of information content, free hCG (beta component) is superior to total hCG as a marker of the risk of genetic abnormalities in the fetus. The rates of beta-hCG with a favorable course of gestation are shown in the table:

10	25,8 – 181,6
11	17,4 – 130,4
12	13,4 – 128,5
13	14,2 – 114,7

This biochemical indicator is one of the most informative. This applies to both the identification of genetic pathology and the marking of the course of the gestation process and the changes occurring in the body of a pregnant woman.

Pregnancy-Associated Plasma Protein-A Rates

This is a specific protein that the placenta produces throughout the gestational period. Its growth corresponds to the period of development of pregnancy, has its own standards for each period. If there is a decrease in the level of PAPP-A in relation to the norm, this is a reason to suspect a threat of the development of a chromosomal abnormality in the fetus (Down and Edwards disease). The norms of PAPP-A indicators in normal gestation are shown in the table:

10	0,46 – 3,73
11	0,79 – 4,76
12	1,03 – 6,01
13	1,47 – 8,54

However, the level of the protein associated with pregnancy loses its informative value after the 14th week (as a marker of the development of Down's disease), since after this period its level in the blood of a pregnant woman carrying a fetus with a chromosomal abnormality corresponds to a normal indicator - as in the blood of a woman who has healthy pregnancy.

Description of the results of the first trimester screening

To evaluate the results of the 1st screening, each laboratory uses a specialized computer product - certified programs that are configured for each laboratory separately. They make a basic and individual calculation of the indicators of the threat for the birth of a baby with a chromosomal abnormality. Based on this information, it becomes clear that all tests are best done in one laboratory.

The most reliable prognostic data are obtained during the first prenatal screening in the first trimester in full (biochemistry and ultrasound). When decoding the data, both indicators of biochemical analysis are considered in combination:

low values of protein-A (PAPP-A) and increased beta-hCG - a threat of the development of Down's disease in a child;
low levels of protein-A and low beta-hCG - a threat of Edwards disease in a baby.
There is a fairly accurate procedure to confirm a genetic abnormality. However, this is an invasive test that can be dangerous for both the mother and the baby. To clarify the need to apply this technique, the data of ultrasound diagnostics are analyzed. In the case of the presence of echo signs of a genetic abnormality on an ultrasound scan, an invasive diagnosis is recommended for a woman. In the absence of ultrasound data indicating the presence of chromosomal pathology, the expectant mother is recommended to repeat the biochemistry (if the period has not reached 14 weeks), or wait for the indications of the 2nd screening study in the next trimester.

Chromosomal abnormalities in fetal development are most easily detected using a biochemical blood test. However, if the ultrasound did not confirm the fears, it is better for the woman to repeat the study after a while, or wait for the results of the second screening.

The information received is processed by a specially created program for solving this problem, which calculates the risks and gives a fairly accurate forecast regarding the threat of the development of fetal chromosomal anomalies (low, threshold, high). It is important to remember that the resulting interpretation of the results is only a forecast, not a final verdict.

In each country, the quantitative expression of the levels varies. Our high level is considered to be less than 1: 100. This ratio means that for every 100 births (with similar test results), 1 child is born with a genetic disorder. This degree of threat is considered an absolute indication for invasive diagnostics. In our country, the threshold level includes the threat of having a baby with developmental defects in the range from 1: 350 to 1: 100.

Threat threshold means that a baby can be born sick with a risk of 1: 350 to 1: 100. At a threshold level of threat, a woman is sent to an appointment with a geneticist, who provides a comprehensive assessment of the data obtained. The doctor, having studied the parameters and anamnesis of the pregnant woman, defines her in the risk group (with its high degree or low). Most often, the doctor recommends waiting until the second trimester screening study, and then, having received a new calculation of threats, again come to the appointment to clarify the need for invasive procedures.

The information described above should not scare expectant mothers, nor do you need to refuse to undergo a first trimester screening. Since most pregnant women have a low risk of carrying a sick baby, they do not need additional invasive diagnostics. Even if the examination showed the poor condition of the fetus, it is better to find out about this in a timely manner and take appropriate measures.

If research has identified a high risk of having a sick child, the doctor must honestly convey this information to the parents. In some cases, invasive research helps to clarify the health situation of the fetus. In case of unfavorable results, it is better for a woman to terminate the pregnancy at an early stage in order to be able to carry a healthy baby. If unfavorable results are obtained, what to do?

If it so happened that the analysis of the indicators of the first trimester screening examination revealed a high degree of threat of the birth of a child with a genetic abnormality, first of all, you need to pull yourself together, since emotions negatively affect the bearing of the fetus. Then start planning further actions.

First of all, it is hardly worth the time and money to be re-screened in another laboratory. If the risk analysis shows a ratio of 1: 100, there is no time to hesitate. You need to immediately contact a geneticist for advice. The less time wasted, the better. With such indicators, most likely, a traumatic method of data confirmation will be prescribed. At 13 weeks, this will be an analysis of the chorionic villus biopsy sample. After 13 weeks, it may be recommended to have a cord or amniocentesis. Chorionic villus biopsy analysis gives the most accurate results. The waiting period for results is about 3 weeks.

In case of confirmation of the development of chromosomal abnormalities of the fetus, the woman will be recommended to artificially terminate the pregnancy. The decision is definitely up to her. But if a decision is made to terminate the pregnancy, then the procedure is best carried out at 14-16 weeks.

First screening rates for pregnancy

Screening of the first trimester, in fact, consists of two procedures that are already familiar to a woman: ultrasound and blood sampling for analysis.

When preparing for your procedures, it is important to follow your doctor's recommendations and try to stay calm.

Ultrasound standards

During an ultrasound examination, a specialist examines in detail the structure of the embryo, specifies the gestational age based on indicators such as the coccygeal-parietal size of the embryo (CTE) and the biparietal size of the fetal head (BPD).

And, most importantly, it makes the necessary measurements, informative for assessing the condition of the fetus.

These are, first of all:

The thickness of the collar space (TVP) is the most important indicator for ultrasound to identify the risk of chromosomal pathologies.

Norms for TBP depending on the age of the embryo

If the TBP exceeds the normal value, then this is a reason to suspect the presence of a chromosomal abnormality in the fetus.

To determine this indicator, it is important to know the exact duration of pregnancy (in weeks and days) and not be late with the examination, since it is impossible to determine the TVP from the second trimester.

Determination of the nasal bone - it is visualized already at 10-11 weeks of pregnancy, and at the 12th week it should be at least 3 mm. This is true for 98% of healthy embryos.
Fetal heart rate (HR) - depending on the week of pregnancy, normal indicators are:

An increased fetal heart rate is also one of the signs of Down syndrome.

The spectrum of blood flow in the Arantia (venous) duct in the fetus. The reverse blood flow waveform is found in only 5% of embryos without chromosomal abnormalities.
The size of the maxillary bone of the fetus - its lag in size is typical for embryos with trisomy.
Bladder volume - At 12 weeks of age, most healthy embryos have a bladder as early as 11 weeks. An enlarged bladder is an additional possible symptom of Down syndrome in the fetus.

Biochemical blood test rates

Blood for screening should be donated, if possible, on the day of the genetic ultrasound scan or, if this is not possible, the next day.

Ideally, blood for the screening test is taken in the morning on an empty stomach, in extreme cases, at least 4 hours after a meal.

In the first trimester, screening to identify the degree of risk of embryonic malformations consists of assessing two indicators: free β-subunit of hCG and PAPP-A.

The "run-up" of the values of these blood markers, acceptable at each stage of pregnancy (by weeks), is quite wide and may differ in the loci of screening, depending on the ethnic composition of the region.

However, in relation to the median of a given region - the average normal value for a particular gestational age - the level of the analyzed indicators should be from 0.5 to 2 MoM.

Moreover, when calculating risks in each individual case, not a pure MoM is taken, but calculated with an amendment to the anamnesis of the expectant mother, the so-called. corrected MoM.

Free β-subunit of hCG

When assessing the risk of developing fetal chromosomal diseases, the analysis of free β-hCG is more informative than the level of the hCG hormone itself.

Because the reason for the change in hCG in a woman may be conditions that are not associated with bearing a baby (hormonal diseases, taking certain medications, etc.).

Whereas a predictable change in the level of the β-subunit of hCG is specific to the state of pregnancy.

With a normally developing embryo, the indicators of free β-hCG in a woman's blood will be approximately as follows:

Determination of the level of the free β-hCG subunit in early pregnancy carries information not only about the possible pathology of fetal development, but also about other conditions of pregnancy or changes in the woman's body.

Provided that the gestational age is set correctly and, neglecting the possibility of a false result, the reasons for the discrepancy between the level of β-hCG in the woman's blood and the gestational age may be completely different reasons that are not related to abnormalities in the development of the fetus.

RAPP-A standards

A pregnancy-specific protein is produced by the outer layer of the placenta and is observed in the woman's blood throughout pregnancy.

Its level increases according to the gestational age.

Lagging of its level from the norm for a specific gestational age can act as one of the signs of the risk of pathologies in the chromosome set of the fetus: Down's and Edwards's syndromes.

The boundaries of the PAPP-A parameters in the patient's blood during a normally developing pregnancy

The value of PAPP-A, as a marker of fetal chromosomal abnormalities, is alarming when the value is lower than the average in the region (MoM is below 0.5). In the first trimester, this may mean the risk of developing Down syndrome, Edwards.

It should be borne in mind that after the 14th week of pregnancy to determine the risk of developing Down syndrome in the fetus, the PAPP-A level is not informative, because compares with indicators of a healthy pregnancy even in the presence of trisomy on chromosome 21.

Interpretation of the results of the first screening

To assess the results of prenatal screening tests, certified computer programs are used, developed specifically for these purposes and configured to work in the home laboratory.

Therefore, all studies must be completed in one institution.

Only combined screening - the assessment of ultrasound data in conjunction with the analysis of biochemical blood markers - becomes the key to obtaining a highly accurate prognosis.

The indicators of a double biochemical test performed in the first trimester of pregnancy are considered in conjunction with each other.

So, a low level of PAPP-A in combination with an increased level of β-hCG in a woman's blood, all other things being equal, gives serious grounds to suspect the development of Down syndrome in the fetus, and in combination with a low level of β-hCG - the risk of developing Edwards syndrome.

In this case, the data of the ultrasound protocol become decisive for making a decision on the direction of a woman for invasive diagnostics.

If the ultrasound does not reveal pathological abnormalities in the fetus, then, as a rule, the expectant mother is recommended to undergo repeated biochemical screening, if the gestational age allows, or to wait for the possibility of undergoing second trimester screening.

Adverse results of the first screening

The screening data is processed by a "smart" computer program, which issues its verdict on the level of risk for the development of chromosomal abnormalities in the fetus: low, threshold or high.

In our country, a risk value of less than 1: 100 is considered high. This means that one in 100 women with similar results from the first screening will have a baby with developmental disabilities.

And such a risk is an unambiguous indication for an invasive examination method in order to diagnose chromosomal diseases of the embryo with a confidence of 99.9%.

Threshold risk means that the chance of having a child with an incurable developmental disability ranges from 1: 350 to 1: 100 cases.

In this situation, a woman needs a consultation with a geneticist, whose task, after an individual admission, is to clarify the expectant mother in the high or low risk group for bearing a fetus with malformations.

As a rule, the geneticist invites the woman to calm down, wait and undergo additional non-invasive examinations in the second trimester (second screening), after which he invites for a second appointment to review the results of the second screening and determine the need for invasive procedures.

Fortunately, the lucky women for whom screening of the first trimester shows a low risk of bearing a sick child: more than 1: 350, the vast majority among future women in labor. They do not need additional examinations.

What to do if the results are unfavorable

If, based on the results of prenatal screening, the expectant mother found a high risk of having a child with congenital malformations, then the primary task for her is to maintain peace of mind and plan her further actions.

Parents-to-be should determine how important it is for them to have accurate information about the presence of pathologies in the development of the unborn child, and in this regard, decide whether to continue examinations to make an accurate diagnosis.

What to do if you get poor results after the first screening?

The first screening should not be repeated in another laboratory.

This will only waste valuable time. And even more so, one should not wait for the second screening.

If you get bad results, you need (at a risk of 1: 100 and below) you should immediately seek advice from a geneticist.

You should not wait for a planned admission to the LCD and seek a referral or an appointment with a geneticist.

You need to immediately find a qualified specialist and attend a paid appointment. The point is, a geneticist will most likely prescribe an invasive procedure for you. If the period is still small (up to 13 weeks), then it will be a chorionic villus sampling.

It is better for all women with a high risk of having a child with genetic abnormalities to undergo a biopsy of the chorionic villi, since the rest of the procedures that allow to identify the genotype of the fetus amniocentesis, cordocentesis are performed at a later date.

The results of any invasive procedure should wait for about 3 weeks. If you do the analysis for a fee, then a little less.

If the abnormalities in the development of the fetus are confirmed, then, depending on the decision of the family, the doctor may issue a referral to terminate the pregnancy.

In this case, the termination of pregnancy will be carried out at a period of 14-16 weeks.

Now imagine if you have an amniocentesis at 16-17 weeks. You are waiting for another 3 weeks of results. And at 20 weeks, you are offered to terminate the pregnancy, when the fetus is already actively moving, when there is already a full realization that a new life is living in your body.

A viable baby can be born in a good clinic after 20 weeks. For a period of more than 20 weeks, abortion is not performed, but artificial childbirth is carried out for medical reasons.

Such interventions break the psyche of the woman and the child's father. It's very hard. Therefore, it is for a period of 12 weeks that a difficult decision should be made - to find out the truth and have an abortion as early as possible. Or take the birth of a special child for granted.

Reliability of screenings and the need for them

From expectant mothers in queues to see a doctor in antenatal clinics, on thematic forums, and sometimes from doctors themselves, you can hear very common opinions about the advisability of screening during pregnancy.

And indeed. Screenings are not very informative. They do not provide a definitive answer to the question of whether your child has a genetic disorder. Screening only gives a probability, and also forms a risk group.

Screening results are not a diagnosis and, moreover, not a verdict.

The first screening gives parents the opportunity to conduct a more accurate diagnosis and terminate a pregnancy at a short time or to prepare as much as possible for the appearance of a special child.

The absence of risks for the development of abnormalities in the development of the fetus, due to chromosomal pathologies, according to screening, will allow a young mother to calmly carry out her pregnancy, being 99% sure that her baby has passed the trouble (because the likelihood of false positive results on screening is negligible).

Disputes about the need for screening, about their moral side, apparently, will not subside soon. However, when answering the question of whether it is worth taking a medical referral for screening, the parents-to-be should mentally move several months ahead and imagine the situation that the risks were justified.

And only after realizing their readiness to accept a special baby, mom and dad can confidently write a waiver or agree to examinations.

Almost every pregnant woman has heard something about the screening of the first trimester of pregnancy (prenatal screening). But often even those who have already passed it do not know what exactly it is prescribed for.

And to expectant mothers who have yet to do this, this phrase in general sometimes seems frightening. And it scares only because the woman does not know how to do it, how to interpret the results obtained later, why the doctor needs it. You will find answers to these many other questions related to this topic in this article.

So, more than once I had to deal with the fact that a woman, upon hearing an incomprehensible and unfamiliar word screening, began to draw terrible pictures in her head that frightened her, making her want to refuse to carry out this procedure. Therefore, the first thing we will tell you is what the word "screening" means.

Screening (English screening - sorting) is a variety of research methods that, due to their simplicity, safety and availability, can be used en masse in large groups of people to identify a number of signs. Prenatal means prenatal. Thus, we can give the following definition of the concept of "prenatal screening".

Screening of the first trimester of pregnancy is a complex of diagnostic tests used in pregnant women at a certain stage of pregnancy to identify gross malformations of the fetus, as well as the presence or absence of indirect signs of fetal pathologies or genetic abnormalities.

The allowed period for screening for the 1st trimester is 11 weeks - 13 weeks and 6 days (see the calculator for calculating the length of pregnancy by weeks). Earlier or later, screening is not carried out, since in this case the results obtained will not be informative and reliable. The most optimal period is considered to be 11-13 obstetric weeks of pregnancy.

Who is referred for first trimester screening?

According to order No. 457 of the Ministry of Health of the Russian Federation of 2000, prenatal screening is recommended for all women. A woman can refuse it, no one will forcibly lead her to these studies, but it is extremely reckless to do this and speaks only of the woman's illiteracy and negligence towards herself and, above all, towards her child.

Risk groups for whom prenatal screening should be mandatory:

Women who are 35 years old or more.
The presence of a threat of early termination of pregnancy.
History of spontaneous miscarriage (s).
History of freezing or regressing pregnancy (s).
The presence of occupational hazards.
Previously diagnosed chromosomal abnormalities and (or) fetal malformations based on the results of screening in past pregnancies, or the presence of children born with such abnormalities.
Women who have had an infectious disease in early pregnancy.
Women who took drugs prohibited for use by pregnant women in early pregnancy.
The presence of alcoholism, drug addiction.
Hereditary diseases in the family of a woman or in the family of the child's father.
The intimate relationship between the child's mother and father.

Prenatal screening at 11-13 weeks of pregnancy consists of two research methods - ultrasound screening for the 1st trimester and biochemical screening.

Screening ultrasound

Preparation for the study: If the ultrasound is performed transvaginally (the sensor is inserted into the vagina), then special preparation is not required. If the ultrasound is performed transabdominally (the sensor is in contact with the anterior abdominal wall), then the study is performed with a full bladder. To do this, it is recommended not to urinate 3-4 hours before it, or an hour and a half before the study, drink 500-600 ml of water without gas.

Prerequisites for obtaining reliable ultrasound data. According to the standards, screening of the first trimester in the form of ultrasound is carried out:

Not earlier than 11 obstetric weeks and not later than 13 weeks and 6 days.
CTE (coccygeal-parietal size) of the fetus is not less than 45 mm.
The position of the child should allow the doctor to adequately carry out all measurements, otherwise, it is necessary to cough, move, walk for a while for the fetus to change its position.

As a result of ultrasound, the following indicators are examined:

CTE (coccygeal-parietal size) - measured from the parietal bone to the coccyx
Head circumference
BPR (biparietal size) - the distance between the parietal tubercles
Distance from the frontal bone to the occipital bone
Symmetry of the cerebral hemispheres and its structure
TVP (collar space thickness)
Heart rate (heart rate) of the fetus
The length of the humerus, femur, as well as the bones of the forearm and lower leg
Location of the heart and stomach in the fetus
The size of the heart and large vessels
Placenta location and thickness
Water quantity
The number of vessels in the umbilical cord
The state of the internal os of the cervix
The presence or absence of uterine hypertonicity

Decryption of the received data:

What pathologies can be detected as a result of ultrasound?

According to the results of ultrasound screening of the 1st trimester, we can talk about the absence or presence of the following anomalies:

Down syndrome is chromosome 21 trisomy, the most common genetic disorder. The prevalence of detection is 1: 700 cases. Thanks to prenatal screening, the birth rate of children with Down syndrome has dropped to 1 in 1100 cases.
Neural tube pathologies (meningocele, meningomyelocele, encephalocele, and others).
Omphalocele is a pathology in which part of the internal organs is located under the skin of the anterior abdominal wall in the hernial sac.
Patau syndrome - trisomy 13 on chromosome. The frequency of occurrence is on average 1: 10,000 cases. 95% of children born with this syndrome die within a few months due to severe damage to internal organs. Ultrasound - rapid fetal heartbeat, impaired development of the brain, omphalocele, slowing down the development of tubular bones.
Edwards syndrome - trisomy on chromosome 18. The frequency of occurrence is 1: 7000 cases. It is more common in children whose mothers are over 35 years old. On ultrasound, there is a decrease in the fetal heart rate, omphalocele, the nasal bones are not visible, one umbilical artery instead of two.
Triploidy is a genetic abnormality in which there is a triple set of chromosomes, instead of a double set. It is accompanied by multiple fetal malformations.
Cornelia de Lange syndrome is a genetic abnormality in which the fetus has various malformations, and in the future, mental retardation. The frequency of occurrence is 1: 10,000 cases.
Smith-Opitz syndrome is an autosomal recessive genetic disorder that is manifested by a metabolic disorder. As a result, the child has multiple pathologies, mental retardation, autism and other symptoms. The frequency of occurrence is on average 1: 30,000 cases.

More about Down's Syndrome Diagnosis

Mainly, ultrasound examination at 11-13 weeks of gestation is performed to detect Down syndrome. The main indicator for diagnosis is:

Collar space thickness (TVP). TVP is the distance between the soft tissues of the neck and the skin. An increase in the thickness of the collar space may indicate not only an increased risk of having a baby with Down syndrome, but also that other genetic pathologies in the fetus are possible.
In children with Down syndrome, the nasal bone is most often not visualized at 11-14 weeks. The contours of the face are smoothed out.

Up to 11 weeks of gestation, the thickness of the collar space is so small that it is impossible to adequately and reliably estimate it. After 14 weeks, the fetus develops a lymphatic system and this space can normally be filled with lymph, so the measurement is also not reliable. The incidence of chromosomal abnormalities in the fetus, depending on the thickness of the collar space.

When decoding the screening data for the 1st trimester, it should be remembered that only one indicator of the thickness of the collar space is not a guide to action and does not speak of a 100% probability of having a disease in a child.

Therefore, the next stage of screening for the 1st trimester is carried out - taking blood to determine the level of β-hCG and PAPP-A. Based on the obtained indicators, the risk of the presence of chromosomal pathology is calculated. If the risk based on the results of these studies is high, then amniocentesis is suggested. This is the collection of amniotic fluid for a more accurate diagnosis.

In especially difficult cases, cordocentesis may be required - taking the umbilical cord blood for analysis. Chorionic villus sampling may also be used. All of these methods are invasive and carry risks to the mother and fetus. Therefore, the decision to conduct them is decided by the woman and her doctor together, taking into account all the risks of carrying out and refusing the procedure.

Biochemical screening of the first trimester of pregnancy

This stage of the study is carried out necessarily after an ultrasound scan. This is an important condition, because all biochemical parameters depend on the gestational age up to the day. The rates of indicators change every day. And ultrasound allows you to determine the duration of pregnancy with the accuracy that is necessary for the correct study. At the time of donating blood, you should already have the results of an ultrasound scan with the indicated gestational age based on the CTE. Also, ultrasound may reveal a frozen pregnancy, regressing pregnancy, in which case further examination does not make sense.

Preparation for research

Blood sampling is performed on an empty stomach! It is undesirable to even drink water in the morning of this day. If the examination is carried out too late, some water may be drunk. It is better to take food with you and have a bite to eat immediately after taking blood than to violate this condition.

2 days before the appointed day of the study, you should exclude from the diet all foods that are strong allergens, even if you have never been allergic to them - these are chocolate, nuts, seafood, as well as very fatty foods and smoked meats.

Otherwise, the risk of getting unreliable results increases significantly.

Consider what deviations from the normal values of β-hCG and PAPP-A may indicate.

β-hCG - chorionic gonadotropin

This hormone is produced by the chorion ("shell" of the fetus), thanks to this hormone, it is possible to determine the presence of pregnancy in the early stages. The level of β-hCG gradually increases in the first months of pregnancy, its maximum level is observed at 11-12 weeks of pregnancy. Then the level of β-hCG gradually decreases, remaining unchanged throughout the second half of pregnancy.

Normal indicators of the level of chorionic gonadotropin, depending on the duration of pregnancy:		An increase in the level of β-hCG is observed in the following cases:	A decrease in the level of β-hCG is observed in the following cases:
Weeks	β-hCG, ng / ml	Down Syndrome Multiple pregnancy Severe toxicosis Diabetes mellitus in the mother	Edwards syndrome Ectopic pregnancy (but this is usually established before biochemical examination) Placental insufficiency High risk of termination of pregnancy
10	25,80-181,60
11	17,4-130,3
12	13,4-128,5
13	14,2-114,8

PAPP-A - Pregnancy Associated Protein-A

This protein, produced by the placenta in the body of a pregnant woman, is responsible for the immune response during pregnancy and is also responsible for the normal development and functioning of the placenta.

MoM coefficient

After receiving the results, the doctor evaluates them by calculating the MoM coefficient. This coefficient shows the deviation of the level of indicators for a given woman from the average normal value. Normally, the MoM-coefficient is 0.5-2.5 (with multiple pregnancies up to 3.5).

The data of the coefficient and indicators may differ in different laboratories, the level of the hormone and protein can be calculated in other units of measurement. You should not use the data in the article as norms for your research. It is necessary to interpret the results together with your doctor!

Further, using the PRISCA computer program, taking into account all the indicators obtained, the woman's age, her bad habits (smoking), the presence of diabetes mellitus and other diseases, the woman's weight, the number of fetuses or the presence of IVF, the risk of having a child with genetic abnormalities is calculated. A high risk is a risk of less than 1 in 380.

Example: If the conclusion indicates a high risk of 1: 280, this means that out of 280 pregnant women with the same indicators, one will have a child with a genetic pathology.

Special situations when the indicators may be different.

IVF - β-hCG values will be higher, and PAPP-A values will be below average.
When a woman is obese, hormone levels may rise.
With multiple pregnancies, β-hCG is higher and the norms for such cases have not yet been established accurately.
Diabetes mellitus in a mother can cause hormone levels to rise.

general information

Some time ago, pregnant women did not know about such a procedure as prenatal or perinatal screening... Now all expectant mothers are undergoing such an examination.

What is pregnancy screening, why is it done and why are its results so important? Answers to these and other questions of concern to many pregnant women about perinatal screening we have tried to give in this material.

In order to exclude in the future any misunderstanding of the information presented, before proceeding directly to the consideration of the above indicated topics, it is worth defining some medical terms.

What is ultrasound screening and maternal serum biochemistry

Prenatal screening Is a special kind of a really standard procedure like screening. This complex examination consists of Ultrasound diagnostics and laboratory research blood, in this particular case biochemistry of maternal serum. Early detection of some genetic abnormalities- this is the main task of such an analysis during pregnancy as screening.

Prenatal or perinatal means prenatal, and by the term screening in medicine, a number of studies of a large stratum of the population are meant, which are carried out in order to form the so-called "risk group" susceptible to certain diseases.

Can be universal or selective screening.

It means that screening tests do not only to pregnant women, but also to other categories of people, for example, children of the same age to establish the diseases characteristic of a given period of life.

With help genetic screening doctors can find out not only about problems in the development of the baby, but also respond in time to complications during pregnancy that a woman may not even know about.

Often, expectant mothers, having heard that they will have to undergo this procedure several times, begin to panic and worry in advance. However, there is nothing to be afraid of, you just need to ask the gynecologist in advance why you need screening for pregnant women, when and, most importantly, how this procedure is done.

So, let's start with what is standard screening carried out three times during the entire pregnancy, i.e. in every trimester... Recall that trimester Is a period of three months.

Screening of the first trimester of pregnancy

What it is 1 trimester screening? First, let's answer a common question about how many weeks it is first trimester of pregnancy... In gynecology, there are only two ways to reliably establish the period during pregnancy - calendar and obstetric.

The first is based on the day of conception, and the second depends on menstrual cycle preceding fertilization... That's why I trimester- this is the period that, according to the calendar method, begins the first week from conception and ends with the fourteenth week.

According to the second method, I trimester Is 12 obstetric weeks. Moreover, in this case, the period is counted from the beginning of the last menstruation. Recently screening not prescribed to pregnant women.

However, now many expectant mothers are themselves interested in undergoing such a survey.

In addition, the Ministry of Health strongly recommends assigning research to all expectant mothers, without exception.

True, this is done voluntarily, since no one can force a woman to undergo any kind of analysis.

It is worth noting that there are categories of women who are simply obliged, for one reason or another, to pass screening, for example:

pregnant women from thirty-five years and onwards;
expectant mothers with a history of information about the presence of a threat spontaneous miscarriage;
women who in the first trimester suffered infectious diseases;
pregnant women who, for health reasons, have to take drugs prohibited for their situation in the early stages;
women who have had various genetic abnormalities or abnormalities in fetal development;
women who have already given birth to children with any deviations or developmental disabilities;
women who have been diagnosed frozen or regressive pregnancy(cessation of fetal development);
suffering from narcotic or alcohol addiction women;
pregnant women in whose family or in the family of the father of the unborn child cases were recorded hereditary genetic abnormalities.

How long do they do prenatal screening for the 1st trimester? For the first screening during pregnancy, the period is set in the interval from 11 weeks to 13 obstetric weeks of pregnancy and 6 days. Earlier, above the indicated period, it makes no sense to conduct this survey, since its results will be uninformative and absolutely useless.

The first ultrasound scan at the 12th week of pregnancy is not done by chance for a woman. Since it is at this time that embryonic and begins fetal or fetal the period of development of the future person.

This means that the embryo turns into a fetus, i.e. there are obvious changes that speak of the development of a full-fledged living human body. As we said earlier, screening tests Is a complex of measures, which consists of ultrasound diagnostics and blood biochemistry of a woman.

It is important to understand that holding screening ultrasound in the 1st trimester during pregnancy plays the same important role as laboratory blood tests. Indeed, in order for geneticists to draw the correct conclusions based on the results of the examination, they need to study both the ultrasound results and the patient's blood biochemistry.

How many weeks the first screening is carried out, we talked, now let's move on to deciphering the results of a comprehensive study. It is really important to consider in more detail the norms established by doctors for the results of the first screening during pregnancy. Of course, only a specialist in this area who has the necessary knowledge, and most importantly, experience, will be able to give a qualified assessment of the results of the analysis.

We believe that it is advisable for any pregnant woman to know at least general information about the main indicators prenatal screening and their normative values. Indeed, it is common for most expectant mothers to be overly suspicious of everything related to the health of their future child. Therefore, they will be much more comfortable if they know in advance what to expect from the research.

Decoding of screening for the 1st trimester by ultrasound, norms and possible deviations

All women know that during pregnancy they have to undergo more than one ultrasound examination (hereinafter referred to as ultrasound), which helps the doctor to track the intrauterine development of the unborn child. To screening ultrasound gave reliable results, you need to prepare in advance for this procedure.

We are sure that the vast majority of pregnant women know how to do this procedure. However, it will not be superfluous to repeat that there are two types of research - transvaginal and transabdominal... In the first case, the sensor of the device is inserted directly into the vagina, and in the second it contacts the surface of the anterior abdominal wall.

Photo of the fetus at 13 weeks of pregnancy

There are no special preparation rules for the transvaginal type of ultrasound.

If you have a transabdominal examination, then before the procedure (about 4 hours before the ultrasound), you should not go to the toilet "on the small", and in half an hour it is recommended to drink up to 600 ml of plain water.

The thing is that the examination must be carried out necessarily on the filled with liquid bladder.

In order for the doctor to obtain a reliable result Ultrasound screening, the following conditions must be met:

examination period - from 11 to 13 obstetric week;
the position of the fetus should allow the specialist to carry out the necessary manipulations, otherwise the mother will have to "influence" the baby to turn over;
coccygeal-parietal size(hereinafter referred to as CTE) should not be less than 45 mm.

What is CTE during pregnancy on ultrasound

When conducting an ultrasound scan, a specialist necessarily examines various parameters or sizes of the fetus. This information allows you to determine how well the baby is formed and whether he is developing correctly. The rates of these indicators depend on the duration of pregnancy.

If the value of one or another parameter obtained as a result of ultrasound deviates from the norm up or down, then this is considered a signal of the presence of some pathologies. Coccyx-parietal size- This is one of the most important initial indicators of the correct intrauterine development of the fetus.

The CTE value is compared with the weight of the fetus and the gestational age. This indicator is determined by measuring the distance from the bone of the crown of the child to his tailbone. As a general rule, the higher the CTE index, the longer the gestation period.

KTR norms

When this indicator slightly exceeds or, on the contrary, is slightly less than the norm, then there is no reason for panic. This only speaks about the peculiarities of the development of this particular child.

If the CTE value deviates from the standards in a large direction, then this signals the development of a large fetus, i.e. presumably the weight of the child at birth will exceed the average rate of 3-3.5 kg. In cases where the CTE is significantly less than the standard values, this may be a sign that:

pregnancy does not develop as it should, in such cases, the doctor should carefully check the fetal heartbeat. If he died in the womb, then the woman needs urgent medical attention ( scraping of the uterine cavity) in order to prevent a possible threat to health ( development of infertility) and life ( infection, bleeding);
the body of a pregnant woman produces an insufficient amount hormones, usually, progesterone, which can lead to spontaneous miscarriage. In such cases, the doctor prescribes an additional examination for the patient and prescribes medications containing hormones ( Utrozhestan, Dufston);
mother is sick infectious diseases, including venereal;
the fetus has genetic abnormalities. In such situations, doctors prescribe additional tests along with biochemical blood test, which is part of the first screening test.

It is also worth emphasizing that there are often cases when a low CTE indicates an incorrectly established gestational age. This refers to a variant of the norm. All a woman needs in such a situation is to undergo a second ultrasound examination after a while (usually after 7-10 days).

Fetal BPD (biparietal size)

What is BPD on ultrasound during pregnancy? When conducting an ultrasound examination of the fetus in the first trimester, doctors are interested in all the possible characteristics of the unborn child. Since their study gives specialists maximum information about how the intrauterine development of a little man takes place and whether everything is in order with his health.

What is it BPD of the fetus? First, let's decipher the medical abbreviation. BPR- this is biparietal fetal head size, i.e. distance between walls parietal bones of the skull, in a simple way, the size of the head. This indicator is considered one of the main ones for determining the normal development of a child.

It is important to note that BPD shows not only how well and correctly the baby is developing, but also helps doctors prepare for the upcoming delivery. Since if the size of the head of the unborn child deviates from the norm in a large direction, then he simply will not be able to pass through the birth canal of the mother. In such cases, a planned cesarean section is prescribed.

Table of BPR norms by week

When BPD deviates from the established norms, this may indicate:

about the presence in the fetus of such pathologies incompatible with life as cerebral hernia or tumor;
about a sufficiently large size of the unborn child, if other basic parameters of the fetus are ahead of the established developmental standards by several weeks;
about abrupt development, which after a while will return to normal, provided that other basic parameters of the fetus fit into the norms;
about fetal development hydrocephalus of the brain caused by the presence of infectious diseases in the mother.

The deviation of this indicator to the lower side indicates that the baby's brain is developing incorrectly.

Collar thickness (TVP)

Fetal TBP- what it is? Collar space by fetus or size cervical fold- This is a place (more precisely, an oblong formation), located between the neck and the upper skin membrane of the baby's body, in which there is an accumulation of fluid. The study of this value is carried out when screening the first trimester of pregnancy, since it is at this time that it is possible to measure TVP for the first time, and then analyze it.

Starting from the 14th week of pregnancy, this formation gradually decreases in size and by the 16th week it practically disappears from view. For TVP, certain norms have also been established, which are in direct proportion to the duration of pregnancy.

For example, the norm collar space thickness at 12 weeks should not exceed the range from 0.8 to 2.2 mm. Collar thickness at 13 weeks should be in the range of 0.7 to 2.5 mm.

It is important to note that for this indicator, experts set averaged minimum values, the deviation from which indicates a thinning of the collar space, which, like the expansion of the TVP, is considered an anomaly.

Fetal TVP table by week

If this indicator does not correspond to the TVP norms indicated in the above table at 12 weeks and at other periods of pregnancy, then such a result most likely indicates the presence of the following chromosomal abnormalities:

trisomy 13, a disease known as Patau syndrome, characterized by the presence of an additional 13 chromosome in human cells;
trisomy on chromosome 21, known to everyone as Down syndrome, a human genetic disease in which karyotype(i.e. a complete set of chromosomes) is represented by chromosome 47 instead of 46;
monosomy on the X chromosome, a genomic disease named after the scientists who discovered it Shereshevsky-Turner syndrome, it is characterized by such anomalies of physical development as short stature, as well as sexual infantilism (immaturity);
trisomy on chromosome 18 Is a chromosomal disease. For Edwards syndrome(the second name of this disease) is characterized by a plurality of malformations incompatible with life.

Trisomy Is an option aneuploidy, i.e. changes karyotype, in which there is an additional third in the human cell chromosome instead of normal diploid set.

Monosomy Is an option aneuploidy (chromosomal abnormality), in which there are no chromosomes in the chromosome set.

What are the norms for trisomy 13, 18, 21 installed during pregnancy? It so happens that in the process of cell division, a failure occurs. This phenomenon has received the name in science aneuploidy. Trisomy- This is one of the varieties of aneuploidy, in which, instead of a pair of chromosomes, an extra third chromosome is present in the cell.

In other words, the child inherits from his parents an additional 13, 18 or 21 chromosome, which in turn entails genetic abnormalities that impede normal physical and mental development. Down Syndrome statistically, this is the most common disease caused by the presence of chromosome 21.

Children born with Edwards syndromes the same as in the case of Patau syndrome, usually do not live up to a year, unlike those who are unlucky to be born with Down syndrome... Such people can live to a ripe old age. However, such a life can rather be called existence, especially in the countries of the post-Soviet space, where these people are considered outcasts and they try to avoid and ignore them.

In order to exclude such anomalies, pregnant women, especially those at risk, must undergo a mandatory screening examination. The researchers argue that the development of genetic abnormalities is in direct proportion to the age of the expectant mother. The younger the woman, the less likely it is that her child will have any abnormalities.

To establish trisomy in the first trimester of pregnancy, a study is carried out collar space of the fetus using ultrasound. In the future, pregnant women periodically take a blood test, in which for geneticists the most important indicators are the level alpha-fetoprotein (AFP), inhibin-A, chorionic gonadotropin (hCG) and estriol.

As mentioned earlier, the risk of having a genetic disorder in a child depends primarily on the age of the mother. However, there are times when trisomy is recorded in young women. Therefore, doctors at screening study all possible signs of anomalies. It is believed that an experienced ultrasound specialist can identify problems already during the first screening examination.

Signs of Down syndrome, as well as Edwards and Patau

Trisomy 13 is characterized by a sharp decrease in the level PAPP-A (PAPP pregnancy-associated protein (protein) A-plasma). Also a marker of this genetic disorder is decreased or increased hCG... The same parameters play an important role in determining whether the fetus has Edwards syndrome.

When there is no risk of trisomy 18, normal values PAPP-A and b-hCG (free beta subunit of hCG) are recorded in a biochemical blood test. If these values deviate from the standards established for each specific gestational age, then, most likely, genetic malformations will be found in the child.

It is important to note that in the case when, during the first screening, a specialist records signs indicating a risk trisomies, the woman is referred for further examination and consultation with geneticists. To make a final diagnosis, the expectant mother will have to undergo procedures such as:

chorionic biopsy, i.e. obtaining a sample of chorionic tissue to diagnose anomalies;
amniocentesis is puncture of the amniotic membrane to get a sample amniotic fluid for the purpose of their further study in the laboratory;
placentocentesis (placental biopsy), given invasive diagnostic method experts take a sample placental tissue using a special puncture needle, which is pierced anterior abdominal wall;
cordocentesis, a method for diagnosing genetic abnormalities during pregnancy, in which the umbilical cord blood of the fetus is analyzed.

Unfortunately, if a pregnant woman has undergone any of the above studies and bioscreening and ultrasound the diagnosis of the presence of genetic abnormalities in the fetus was confirmed, doctors will offer to terminate the pregnancy. In addition, unlike standard screening studies, the data invasive examination methods can provoke a number of severe complications up to spontaneous miscarriage, so doctors resort to them in a fairly rare number of cases.

Nasal bone at 12 weeks, table of norms

Nasal bone- This is a slightly elongated, quadrangular, convex in front of the paired bone of the human face. At the first ultrasound screening, the specialist determines the length of the baby's nose bone. It is believed that in the presence of genetic abnormalities, this bone does not develop correctly, i.e. its ossification occurs later.

Therefore, if the nasal bone is absent or its size is too small during the first screening, then this indicates the possible presence of various anomalies. It is important to emphasize that the length of the nasal bone is measured at 13 weeks or 12 weeks. When screened at 11 weeks, the specialist checks only for its presence.

It is worth emphasizing that if the size of the nasal bone does not correspond to the established norms, but if other basic indicators correspond, there is really no reason for concern. This state of affairs may be due to the individual characteristics of the development of this particular child.

Heart rate (HR)

A parameter such as Heart rate plays an important role not only in the early stages, but throughout pregnancy. Constantly measure and monitor fetal heart rate it is only necessary to notice deviations during the time and, if necessary, save the baby's life.

The interesting thing is that though myocardium (heart muscle) begins to decrease already in the third week after conception, you can hear the heartbeat only starting from the sixth obstetric week. It is believed that at the initial stage of fetal development, the rhythm of its heartbeats should correspond to the mother's pulse (on average, it is 83 beats per minute).

However, already in the first month of intrauterine life, the number of baby's heartbeats will gradually increase (by about 3 beats per minute every day) and by the ninth week of pregnancy it will reach 175 beats per minute. Determine the fetal heart rate using ultrasound.

When conducting the first ultrasound, specialists pay attention not only to the heart rate, but also watch how the baby's heart develops. For this, the so-called four-chamber cut, i.e. method of instrumental diagnostics of heart defects.

It is important to emphasize that a deviation from the standards of such an indicator as heart rate indicates the presence of malformations of the heart... Therefore, doctors carefully study the structure on a cut atria and fetal heart ventricles... If any deviations are found, specialists refer the pregnant woman for additional research, for example, to echocardiography (ECG) with dopplerography.

Starting from the twentieth week, the gynecologist of the antenatal clinic will listen to the baby's heart using a special tube at each scheduled visit to the pregnant woman. A procedure such as auscultation of the heart does not apply at an earlier date due to its ineffectiveness, since the doctor just can't hear the heartbeat.

However, as the baby develops, his heart will be heard more clearly each time. Auscultation helps the gynecologist determine the position of the fetus in the womb. For example, if the heart is better heard at the level of the mother's navel, then the child is in a transverse position, if the navel is on the left or below, then the fetus is in cephalic presentation, and if above the navel, then in pelvic.

From 32 weeks of gestation, to control the heartbeat, use cardiotocography(abbreviated CTE). When carrying out the above types of examinations, a specialist can record in the fetus:

bradycardia, i.e. abnormally low heart rate, which is usually temporary. This deviation may be a symptom of the mother's autoimmune diseases, anemia, preeclampsia as well as cord clamping when the unborn baby is not getting enough oxygen. Bradycardia can be caused by congenital heart defects in order to exclude or confirm this diagnosis, a woman is sent for additional examinations without fail;
tachycardia, i.e. high heart rate. Experts rarely record such a deviation. However, if the heart rate is much higher than that provided for by the norms, then this indicates hyperthyroidism from the mother or hypoxia, development intrauterine infections, anemia and genetic abnormalities at the fetus. In addition, the medications a woman takes can affect heart rate.

In addition to the above characteristics, during the first screening ultrasound examination, specialists also analyze the data:

about symmetry cerebral hemispheres fetus;
about the size of the circumference of his head;
about the distance from the occipital to the frontal bone;
the length of the bones of the shoulders, thighs and forearms;
about the structure of the heart;
about the location and thickness of the chorion (placenta or "child's place");
the amount of water (amniotic fluid);
about the condition of the pharynx cervix mothers;
the number of vessels in the umbilical cord;
about absence or presence hypertonicity of the uterus.

As a result of an ultrasound scan, in addition to the genetic abnormalities already discussed above ( monosomy or Shereshevsky-Turner syndrome, trisomy on chromosome 13, 18 and 21, namely Down, Patau and Edwards syndromes) the following pathologies in development can be identified:

neural tube, for example, malformation of the spine (meningomyelocele and meningocele) or cranial hernia (encephalocele);
Cornet de Lange syndrome, an anomaly in which multiple malformations are recorded, entailing both physical abnormalities and mental retardation;
triploidy, a genetic malformation, in which a failure occurs in the chromosome set, as a rule, the fetus does not survive in the presence of such a pathology;
omphalocele, embryonic or umbilical hernia, pathology of the anterior abdominal wall, in which some organs (liver, intestines and others) develop in the hernial sac outside the abdominal cavity;
Smith-Opitz syndrome, a genetic disorder that affects the processes metabolism, which subsequently leads to the development of many severe pathologies, for example, autism or mental retardation.

Biochemical screening of the 1st trimester

Let's talk in more detail about the second stage of a comprehensive screening examination of pregnant women. What it is biochemical screening of the 1st trimester, and what are the norms established for its main indicators? Actually, biochemical screening Is nothing more than biochemical analysis blood of the future mother.

This study is carried out only after an ultrasound scan. This is due to the fact that, thanks to an ultrasound examination, the doctor establishes the exact duration of pregnancy, on which the normative values of the main indicators of blood biochemistry directly depend. So, remember that you only need to go for a biochemical screening with the results of an ultrasound scan.

How to prepare for your first pregnancy screening

We talked about how they do it, and most importantly, when they do a screening ultrasound, now it is worth paying attention to preparing for the delivery of a biochemical analysis. As with any other blood test, you need to prepare for this test well in advance.

If you want to get a reliable result of biochemical screening, then you will have to exactly follow the following recommendations:

blood for biochemical screening is given strictly on an empty stomach, doctors do not even recommend drinking plain water, not to mention any food;
a few days before the screening, you should change your usual diet and start adhering to a sparing diet, in which you can not eat too fatty and spicy foods (so that the level of cholesterol), as well as seafood, nuts, chocolate, citrus fruits and other allergenic foods, even if you have not previously had an allergic reaction to anything.

Strict adherence to these recommendations will allow you to get a reliable result of biochemical screening. Believe me, it is better to be patient for a while and give up your favorite delicacies, so that later you do not worry about the results of the analysis. After all, any deviation from the established norms will be interpreted by doctors as a pathology in the development of the baby.

Quite often, in all kinds of forums devoted to pregnancy and childbirth, women talk about how the results of the first screening, expected with such excitement, turned out to be bad, and they had to do all the procedures again. Fortunately, the pregnant women ended up receiving good news about the health of their babies, since the adjusted results indicated that there was no developmental disability.

The whole point was that the expectant mothers did not prepare properly for the screening, which ultimately led to the receipt of inaccurate data.

Imagine how many nerves were wasted and bitter tears were shed while women were waiting for new test results.

Such colossal stress does not pass without leaving a trace for the health of any person, and even more so for a pregnant woman.

Biochemical screening of the 1st trimester, interpretation of the results

When conducting the first biochemical screening analysis, the main role in diagnosing any abnormalities in fetal development is played by such indicators as free β-subunit of human chorionic gonadotropin(Further HCG), and PAPP-A (Plasma Protein A Associated with Pregnancy)... Let's consider each of them in detail.

PAPP-A - what is it?

As mentioned above, PAPP-A- This is an indicator of a biochemical blood test of a pregnant woman, which helps specialists to establish at an early stage the presence of genetic pathologies of fetal development. The full name of this value sounds like pregnancy associated plasma protein A, which literally means - pregnancy-associated plasma protein A.

It is the protein (protein) A produced by the placenta during pregnancy that is responsible for the harmonious development of the unborn child. Therefore, an indicator such as the level of PAPP-A, calculated at 12 or 13 weeks during pregnancy, is considered a characteristic marker for determining genetic abnormalities.

It is mandatory to pass the analysis to check the level of PAPP-A:

pregnant women over the age of 35;
women who have previously given birth to children with genetic developmental disabilities;
mothers-to-be with family members with genetic developmental disabilities;
women who have had diseases such as cytomegalovirus, rubella, herpes or hepatitis shortly before pregnancy;
pregnant women who have had complications or miscarriages before.

Normative values of such an indicator as PAPP-A depend on the duration of pregnancy. For example, the PAPP-A rate at 12 weeks is 0.79 to 4.76 mU / ml, and at 13 weeks - from 1.03 to 6.01 mU / ml. In cases where, as a result of the test, this indicator deviates from the norm, the doctor prescribes additional studies.

If the analysis reveals a low level of PAPP-A, then this may indicate the presence of chromosomal abnormalities in the development of the child, for example, Down syndrome it also signals the risk of spontaneous miscarriage and regressive pregnancy... When this indicator is increased, then this is most likely the result of the fact that the doctor could not calculate the correct gestational age.

That is why blood biochemistry is taken only after an ultrasound scan. However high PAPP-A may indicate the likelihood of developing genetic abnormalities in the development of the fetus. Therefore, in case of any deviation from the norm, the doctor will send the woman for additional examination.

Scientists gave this name to this hormone for a reason, since it is thanks to it that one can reliably find out about pregnancy already 6-8 days after fertilization has occurred egg cells. It is noteworthy that HCG begins to develop chorionic already in the first hours of pregnancy.

Moreover, its level is growing rapidly and by 11-12 weeks of pregnancy exceeds the initial values by a factor of thousands. Then human chorionic gonadotropin is gradually losing ground, and its indicators remain unchanged (starting from the second trimester) until childbirth. All pregnancy test strips contain hCG.

If the level human chorionic gonadotropin increased, then this may indicate:

about the presence of the fetus Down syndrome;
O multiple pregnancy;
about the development of the mother diabetes mellitus;
O toxicosis.

When the hCG level is below the prescribed standards, it says:

about the possible Edwards syndrome at the fetus;
about the risk miscarriage;
O placental insufficiency.

After a pregnant woman has undergone an ultrasound scan and blood biochemistry, a specialist must decipher the results of the examination, as well as calculate the possible risks of developing genetic abnormalities or other pathologies using a special computer program PRISCA (Prisca).

The screening summary sheet will contain the following information:

about age risk developmental anomalies(depending on the age of the pregnant woman, possible deviations change);
about the values of biochemical parameters of a woman's blood test;
about the risk of possible diseases;
MoM coefficient.

In order to calculate as reliably as possible the possible risks of developing certain abnormalities in the fetus, experts calculate the so-called MoM (multiple of median) coefficient. To do this, all the screening data obtained is entered into a program that plots the deviation of each indicator of the analysis of a particular woman from the average norm established for most pregnant women.

MoM is considered normal if it does not go beyond the range of values from 0.5 to 2.5. At the second stage, this coefficient is adjusted taking into account age, race, presence of diseases (for example, diabetes), bad habits (for example, smoking), the number of previous pregnancies, ECO and other important factors.

At the final stage, the specialist makes a final conclusion. Remember, only a doctor can correctly interpret the screening results. In the video below, the doctor explains all the key points related to the first screening.

Screening cost for 1 trimester

The question of how much this study costs and where it is best to take it, worries many women. The thing is that not every state polyclinic can do such a specific examination for free. Based on the reviews left on the forums, many expectant mothers do not trust free medicine at all.

Therefore, you can often come across the question of where to do screening in Moscow or other cities. If we talk about private institutions, then in a fairly well-known and well-proven laboratory INVITRO, biochemical screening can be done for 1600 rubles.

True, this cost does not include ultrasound, which the specialist will definitely ask to present before the biochemical analysis. Therefore, you will have to separately undergo an ultrasound examination in another place, and then go to the laboratory to donate blood. Moreover, this must be done on the same day.

Second screening during pregnancy, when to do and what is included in the study

According to the recommendations of the World Health Organization (hereinafter WHO), every woman is obliged to undergo three screenings throughout the entire period of pregnancy. Although nowadays gynecologists refer all pregnant women for this examination, there are those who, for whatever reason, miss the screening.

However, for some categories of women, such a study should be mandatory. This applies primarily to those who have previously given birth to children with genetic deviations or developmental defects. In addition, it is mandatory to undergo screening:

women over the age of 35, since the risk of developing various pathologies in the fetus depends on the age of the mother;
women who took drugs or other prohibited drugs for pregnant women in the first trimester;
women who have previously suffered two or more miscarriages;
women who suffer from one of the following inherited diseases to a child - diabetes mellitus, diseases of the musculoskeletal system and cardiovascular system, and oncopathology;
women who are at risk of spontaneous miscarriage.

In addition, future mothers should definitely undergo screening if they or their spouses were exposed to radiation before conception, and also transferred immediately before or during pregnancy. bacterial and infectious diseases... As with the first screening for the second time, the expectant mother must also do an ultrasound scan and take a biochemical blood test, which is often called a triple test.

Timing of the second screening during pregnancy

So, let's answer the question of how many weeks do the second screening during pregnancy. As we have already determined, the first study is carried out in the early stages of pregnancy, namely in the period from 11 to 13 weeks of the first trimester. The next screening study is carried out during the so-called "golden" period of pregnancy, i.e. in the second trimester, which starts at 14 weeks and ends at 27 weeks.

The second trimester is called golden, because it was during this period of time that all the initial ailments associated with pregnancy ( nausea, weakness, drowsiness and others) retreat, and a woman can fully rejoice in her new state, since she feels a powerful surge of strength.

A woman should visit her gynecologist every two weeks so that she can monitor the progress of her pregnancy.

The doctor gives the expectant mother recommendations regarding her interesting situation, and also informs the woman about what examinations and how long she should undergo. Typically, a pregnant woman takes a urine test and a general blood test before each visit to the gynecologist, and the second screening takes place from 16 to 20 weeks of pregnancy.

Ultrasound screening of the 2nd trimester - what is it?

During the second screening first, they undergo an ultrasound to determine the exact duration of pregnancy, so that later specialists can correctly interpret the results of a biochemical blood test. On Ultrasound the doctor studies the development and size of the internal organs of the fetus: the length of the bones, the volume of the chest, head and abdomen, the development of the cerebellum, lungs, brain, spine, heart, bladder, intestines, stomach, eyes, nose, as well as the symmetry of the structure of the face.

In general, everything that is visualized with the help of ultrasound examination is analyzed. In addition to studying the main characteristics of the baby's development, experts check:

how the placenta is located;
the thickness of the placenta and the degree of its maturity;
the number of vessels in the umbilical cord;
the condition of the walls, appendages and cervix;
the quantity and quality of amniotic fluid.

Norms for ultrasound screening of the 2nd trimester of pregnancy:

Decoding the triple test (biochemical blood test)

In the second trimester, experts pay special attention to three markers of genetic abnormalities, such as:

chorionic gonadotropin- this is hormone produced by the fetal chorion;
alpha-fetoprotein ( Further AFP) - this is plasma protein (protein), originally generated corpus luteum, and then produced liver and gastrointestinal tract of the fetus;
free estriol ( further hormone E3) Is a hormone that is produced in placenta, and fetal liver.

In some cases, they also study the level inhibin (hormone, produced follicles)... Certain standards are set for each week of pregnancy. It is considered optimal to conduct a triple test at 17 weeks of gestation.

When the level of hCG at the second screening is overestimated, then this may indicate:

about multiple pregnancy;
O diabetes mellitus from the mother;
O toxicosis;
about the risk of development Down syndrome if the other two indicators are below normal.

If hCG, on the contrary, is lowered, then this says:

O ectopic pregnancy;
about the risk Edwards syndrome;
O frozen pregnancy;
O placental insufficiency.

When the AFP level is high, then there is a risk of:

the presence of developmental abnormalities kidney;
defects neural tube;
duodenal atresia;
developmental disabilities abdominal wall;
damage brain;
lack of water;
fetal death;
spontaneous miscarriage;
emergence rhesus conflict.

Decreased AFP can be a signal:

Edwards syndrome;
diabetes mellitus mothers;
low location placenta.

At a low level estriol high risk:

development anemia at the fetus;
adrenal and placental insufficiency;
spontaneous miscarriage;
availability Down syndrome;
development intrauterine infection;
delays in the physical development of the fetus.

It should be noted that the level hormone E3 some drugs (for example, antibiotics), as well as improper and unbalanced nutrition of the mother. When E3 is elevated, doctors diagnose diseases kidney or multiple pregnancy, and also predict preterm birth, when the level of estriol rises sharply.

After the expectant mother passes two stages of screening, doctors analyze the information received using a special computer program and calculate the same MoM coefficient as in the first study. In the conclusion, the risks for this or that type of deviation will be indicated.

Values are indicated as a fraction, for example 1: 1500 (i.e. one case per 1500 pregnancies). The norm is considered if the risk is less than 1: 380. Then the conclusion will indicate that the risk is below the cut-off threshold. If the risk is higher than 1: 380, then the woman will be referred for additional consultation with geneticists or offered to undergo invasive diagnostics.

It should be noted that in cases when at the first screening the biochemical analysis corresponded to the norms (indicators were calculated HCG and PAPP-A), then for the second and third time it is enough for a woman to do only an ultrasound.

Third screening during pregnancy

The last screening examination of the expectant mother takes place in third trimester... Many people wonder what they are looking at at the third screening and when this study should be done.

As a rule, if the pregnant woman was not diagnosed with any abnormalities in the development of the fetus or during pregnancy at the first or second examination, then she only needs to undergo an ultrasound examination, which will allow the specialist to draw final conclusions about the condition and development of the fetus, as well as its position in the womb.

Determination of the position of the fetus ( cephalic or breech presentation) is considered an important preparatory stage before childbirth.

In order for the delivery to be successful, and the woman can give birth on her own without surgery, the child must be in a cephalic presentation.

Otherwise, doctors plan a cesarean section.

The third screening includes procedures such as:

Ultrasound, which all pregnant women go through;
dopplerography Is a technique that focuses mainly on the state of blood vessels placenta;
cardiotocography- a study that allows you to more accurately determine the heart rate of a child in the womb;
blood biochemistry, during which attention is focused on such markers of genetic and other abnormalities as the level HCG, ɑ-fetoprotein and PAPP-A.

Timing of the third screening during pregnancy

It is worth noting that only the doctor decides at how many weeks 3 a woman should undergo screening, based on the individual characteristics of this particular pregnancy. However, it is considered optimal when the expectant mother undergoes a planned ultrasound scan at 32 weeks, and then immediately takes a biochemical blood test (if any), and also undergoes other necessary procedures.

However, for medical reasons, carry out dopplerography or CTG the fetus can be from 28 weeks of gestation. Third trimester starts at 28 weeks and ends with childbirth at 40-43 weeks. The last screening ultrasound is usually prescribed at 32-34 weeks.

Decoding ultrasound

How long does it take for a pregnant woman to undergo the third screening ultrasound, now we will talk in more detail about decoding the study. When conducting an ultrasound scan in the third trimester, the doctor pays special attention to:

for development and structure of cardio-vascular system a child to exclude possible developmental pathologies, for example, heart disease;
for correct development brain, organs of the abdominal cavity, spine and genitourinary system;
on located in the cranial cavity vein of Galen which plays an important role in the proper functioning of the brain in order to exclude aneurysm;
on the structure and development of the child's face.

In addition, ultrasound allows the specialist to assess the condition amniotic fluid, appendages and uterus mother and also check maturity and the thickness of the placenta... In order to exclude hypoxia and pathology in the development of the nervous and cardiovascular system, as well as to reveal the features of blood flow in vessels of the uterus and the child, as well as in the umbilical cord, spend dopplerography.

As a rule, this procedure is carried out only according to indications simultaneously with an ultrasound scan. In order to exclude fetal hypoxia and define Heart rate, spend CTG... This type of research focuses exclusively on the baby's heart, so cardiotocography prescribed in cases where the doctor has concerns about the condition cardiovascular child's systems.

Ultrasound in the third trimester of pregnancy allows you to determine not only the presentation of the child, but also the maturity of his lungs, on which the readiness for birth depends. In some cases, hospitalization for early delivery may be required to keep the baby and mother alive.

Index	Average rate for 32-34 weeks of pregnancy
Placenta thickness	from 25 to 43 mm
Amniotic (amniotic) index	80-280 mm
Placental maturity	1-2 degree of ripening
Uterine tone	absent
Uterine pharynx	closed, length not less than 3 cm
Fetal growth	on average 45 cm
Fruit weight	on average 2 kg
Fetal abdominal girth	266 - 285 mm
BPR	85-89 mm
Fetal femur length	62-66 mm
Fetal chest girth	309-323 mm
Fetal forearm size	46-55 mm
Fetal shin bone size	52-57 mm
Fetal Shoulder Length	55-59 mm

Based on the results of a biochemical blood test MoM factor should not deviate from the range from 0.5 to 2.5. The risk value for all possible deviations should correspond to 1: 380.

1 pregnancy screening is the most exciting first trimester event. With bated breath, the expectant mother is waiting for news about her child - the woman does not know anything about him yet! How does the baby develop? Is everything all right with him? The survey will not leave any of these questions unanswered.

The concept of "screening" literally translated from a foreign language means "sifting" and accurately reflects the specifics of the procedure. It is as if expectant mothers are "sifted" when the indicators of the intrauterine state of their children are determined. Screening is carried out at 11-13 weeks of gestation. This is a mandatory procedure for all expectant mothers. Such an early period will not prevent accurate equipment and experienced specialists from detecting abnormalities in the development of the fetus, caused by genetics or chromosomal damage.

Features of the first screening examination

Of paramount importance is a comprehensive examination for pregnant women of the following high-risk groups:

the mom-to-be celebrated her 35th birthday;
in the patient's family, there were cases of the birth of children with Down syndrome and other anomalies on the basis of genetics;
women who had spontaneous abortion or had sick (with genetic abnormalities) children;
victims of infectious diseases that overtook women some time after conception.

The examination includes two procedures: ultrasound and biochemical screening, during which markers are found in the blood that are specific to the "interesting" position. These research methods can tell the doctor a lot: whether the growth rate of the baby corresponds to the gestational age and whether there are any pathologies in its development. The test results are interpreted taking into account the age and body weight of the expectant mother, as well as the presence of chronic diseases and bad habits in her.

When decoding the data obtained as a result of the examination, the specialist pays attention not only to absolute indicators, but also to deviations corresponding to the time of screening during pregnancy. All doctors agree that the results of a clinical blood test cannot be taken as the ultimate truth and on this basis a final diagnosis cannot be made. Whatever the results of the study, there is always the opportunity to undergo additional examination.

How pregnancy screening is done

Preparation for the procedure begins within the walls of the antenatal clinic, where the expectant mother can ask the gynecologist any questions that interest her. The specialist will talk to the woman about the importance of the first screening and explain how to prepare for it.
The laboratory usually performs ultrasound and biochemical blood tests on the same day. The examination is completely painless; only the procedure for taking blood can be considered the most unpleasant moment.

Screening is done early in the morning, before breakfast. 1 - 2 days before the procedure, the expectant mother should pull herself together and give up her favorite foods, including chocolate, seafood, meat and all fatty foods. A forced diet is considered the key to accurate screening results.

The doctor will most likely advise the woman to refrain from sexual intercourse, otherwise the overall picture of the tests may be distorted.

Before going to the laboratory, the pregnant woman must weigh herself. The laboratory assistant will enter the data on the patient's body weight into a special form immediately before the ultrasound procedure and blood sampling for analysis.

Before screening, it is better not to drink water, but if the desire is overwhelming, then no more than 100 ml.

Screening during pregnancy: the purpose of ultrasound

At the initial stage of gestation, an ultrasound machine is used to determine the main parameters of a growing baby. The laboratory assistant examines the internal organs of the child, pays attention to the location of his arms and legs. In addition, the procedure makes it possible to see the position of the placenta and assess its structure. By the peculiarities of the baby's physique during this period of pregnancy, it can be judged whether the fetus is forming correctly. If a deviation in the development of a child from generally accepted norms is detected on time, the doctor will have time to conduct an additional examination, think over and develop tactics for further pregnancy management.

During the procedure, a specialist studies such specific features of a developing child:

Coccyx-parietal distance (CTE)

11 weeks - from 34 to 50 mm;
12 weeks - from 42 to 59 mm;
13 weeks - 51 to 75 mm.

Condition of the nasal bone

At 11 weeks of gestation, it should be clearly visible, but its size is still difficult to determine. Screening at 12 weeks of gestation shows that the nasal bone has grown - now its size ranges from 2 to 2.5 mm or more. At 10 - 12 weeks of gestation, the bone is clearly visible in 98% of healthy babies.

Collar thickness (TVP)

In other words, these are folds in the neck.

11 weeks - from 0.8 to 2.2 mm;
12 - 13 weeks - from 0.8-2.7 mm.

Heart rate (HR)

11 weeks - from 155 to 178 beats per minute;
12 weeks - from 150 to 174 beats per minute;
13 weeks - 147 to 171 beats per minute

Biparietal size

This is the distance between the outer and inner edges of both parietal bones.

11 weeks - from 13 to 21 mm;
12 weeks - from 18 to 24 mm;
13 weeks - 20 to 28 mm.

The appearance of the maxillary bone

A poorly expressed maxillary bone at 11 to 13 weeks may indicate a high risk of developing Down syndrome in a baby.

Based on these indicators, the doctor can draw a conclusion about the characteristics of the child's development. So the presence of a number of specific signs on the monitor of the ultrasound machine can inform the specialist about the possible pathologies of the baby's development. Let's note what they pay attention to in the first place:

if the nasal bone is still not identified in the fetus within the established screening times during pregnancy or its size is significantly behind the norm, and the facial contours are inexpressive and smoothed, the specialist will suspect Down syndrome;
completely invisible or very small nasal bone, the presence of an umbilical hernia, one umbilical artery instead of two, and a low heart rate indicates Edwards syndrome;
visualized umbilical cord hernia, developmental disorder of many body systems and high heart rate are most likely indicative of the development of Patau syndrome.

Screening during pregnancy: blood test norms

As a result of a biochemical blood test, the indicators of free beta-hCG and protein-A (PAPP-A) are of the greatest value to the doctor.

In a pregnant woman, the amount of human chorionic gonadotropin in the blood is increased. An increase in the concentration of a specific substance occurs at a rapid pace in the first weeks after fertilization of the egg. It is on this basis that one can judge whether a pregnancy has taken place or not already 6 to 7 days after intercourse.

Starting from the 12th week of gestation, the hCG levels in the body begin to gradually decrease, and its level remains practically unchanged throughout the second trimester.

The norms of free hCG during pregnancy are:

17.4 to 130.4 ng / ml at 11 weeks of gestation;
13.4 to 128.5 ng / ml at 12 weeks of gestation;
from 14.2 to 114.7 ng / ml at 13 weeks of gestation.

A free hCG level higher than normal may indicate the following conditions:

multiple pregnancy;
Down syndrome;
severe toxicosis.

Significantly underestimated indicators of this substance indicate such probable pathologies:

undeveloped pregnancy;
delayed fetal development;
the likelihood of spontaneous miscarriage;
Edwards syndrome.

The norms for the substance PAPP-A are:

from 0.46 to 3.73 mU / ml at 11 weeks;
from 0.79 to 4.76 mU / ml at 12 weeks;
from 1.03 to 6.01 mU / ml at 13 weeks.

pathology of the development of the neural tube of the fetus;
frozen pregnancy;
the likelihood of spontaneous abortion;
the risk of premature birth;
Rh-conflict between mother and child;
Edwards syndrome;
Down syndrome;
Smith-Opitz syndrome;
Cornelia de Lange syndrome.

Biochemical analysis of the first screening during pregnancy can detect fetal pathologies in the form of Down, Patau and Edwards syndromes in 68% of cases. Taking into account the ultrasound data, the reliability of the blood test results is confirmed in 90% of cases. However, experts always remember that, for some reason, the data obtained may be distorted.

For example, the results of a biochemical blood test depend on many factors, among which the following have the greatest influence on the blood composition:

multiple pregnancy;
pregnancy that was obtained using the IVF procedure;
large body weight of the patient (the more it is, the higher the indicators of specific substances in the blood);
a course of treatment with drugs, the active substance of which is progesterone;
diabetes mellitus in a pregnant woman;
high risk of spontaneous abortion;
incorrectly established gestational age;
depressed state of the expectant mother due to psychological trauma.

If the data obtained from the first screening during pregnancy does not differ too much from the norm, doctors will try to allay their concerns at a second screening. This is a mandatory procedure for the second trimester of pregnancy.

Medical practice knows cases when, despite the unfavorable results of the biochemical blood test of the first and second screenings, absolutely healthy children were born in women. Note that this "miracle" has to do only with a blood test, since doctors almost never doubt the reliability of the results obtained during the ultrasound procedure.

Remember that unfavorable results from the first screening are not yet a reason to panic, as the test rates may vary depending on your health condition. You have the right to an additional examination of your own free will. You need to start with a consultation with a geneticist, who will discuss with you the possibility of conducting additional research methods. These are amniocentesis, cordocentesis, or chorionic villus sampling. These procedures will answer your innermost question with amazing precision. A kind of bonus that these events will bring you will be the absolutely truthful news about who you are wearing under your heart - a future protector or a princess. This will be revealed by counting the chromosomes. In any case, you need to keep your hands on and hope for the best!

The hopes and concerns of the first pregnancy screening. Video

Screening of the 1st trimester is a diagnostic study that is carried out for pregnant women at risk from 10 to 14 weeks. It, being the first of two screening observations, allows you to determine with great accuracy how high the risk of having a sick fetus is. Such an examination consists of two parts - blood donation from a vein and an ultrasound scan. Based on them, taking into account many of your individual factors, the geneticist makes his verdict.

Screening (from the English. "Screening") is a concept that includes a number of measures for the detection and prevention of diseases. For example, screening during pregnancy provides the doctor with complete information about the various risks of pathologies and complications in the development of the child. This makes it possible to take in advance the full range of measures to prevent diseases, including the most severe ones.

Who needs to be screened for the 1st trimester

It is very important that the following women undergo the study:

closely related to the child's father
who have had 2 or more miscarriages (preterm birth)
had a frozen pregnancy or stillbirth
the woman has had a viral or bacterial disease during pregnancy
there are relatives suffering from genetic pathologies
this couple already has a child with Patau, Down syndrome or others
there was an episode of treatment with drugs that cannot be used during pregnancy, even if they were prescribed for vital signs
pregnant over 35 years old
both parents-to-be want to check the likelihood of a sick fetus being born.

What are looking for at the first ultrasound screening during pregnancy

What do they look at at the first screening? The length of the embryo is assessed (this is called the coccygeal-parietal size - CTE), the size of the head (its circumference, biparietal diameter, the distance from the forehead to the back of the head).

The first screening shows the symmetry of the cerebral hemispheres, the presence of some of its structures, which are mandatory in this period. Look at 1 screening also:

long tubular bones, the length of the humerus, femur, forearm and lower leg is measured
whether the stomach and heart are in certain places
the size of the heart and the vessels emanating from them
the size of the abdomen.

What pathology does this examination reveal?

The first pregnancy screening is informative in terms of detecting:

pathology of the rudiment of the central nervous system - neural tube
Patau syndrome
omphalocele - an umbilical hernia, when a different number of internal organs are located outside the abdominal cavity, and in the hernial sac above the skin
Down syndrome
triploidy (triple set of chromosomes instead of double)
Edwards syndrome
Smith-Opitz syndrome
de Lange syndrome.

The timing of the study

When should the first screening be done? The timing of the diagnosis of the 1st trimester is very limited: from the first day of the 10th week to the 6th day of the 13th week. It is better to do the first screening in the middle of this range, at 11-12 weeks, since the error in the calculations significantly reduces the accuracy of the calculation.

Your doctor should once again scrupulously and thoroughly, depending on the date of the last menstruation, calculate how long you should undergo the first examination of this kind.

How to prepare for the study

First trimester screening is done in two stages:

First, an ultrasound screening is done. If this is done transvaginally, then no preparation is required. If by the abdominal method, then it is necessary that the bladder is full. To do this, you need to drink half a liter of water half an hour before the study. By the way, the second screening during pregnancy is carried out transabdominally, but does not require preparation.
Biochemical screening. This word is called the collection of blood from a vein.

Given the two-stage study, preparation for the first study includes:

filling the bladder - before 1 ultrasound screening
fasting for at least 4 hours before taking blood from a vein.

In addition, a diet is needed before the diagnosis of the 1st trimester in order for the blood test to give an accurate result. It consists in excluding the intake of chocolate, seafood, meat and fatty foods the day before you plan to attend a screening ultrasound scan during pregnancy.

If you plan (and this is the best option for perinatal diagnostics of the 1st trimester) to undergo ultrasound diagnostics and donate blood from a vein in one day, you need:

all the previous day, deny yourself allergenic products: citrus fruits, chocolate, seafood
exclude completely fatty and fried foods (1-3 days before the study)
before the study (usually blood is donated for screening for 12 weeks before 11:00) go to the toilet in the morning, then either not urinate for 2-3 hours, or an hour before the procedure, drink half a liter of water without gas. This is necessary if the study will be performed through the abdomen.
if ultrasound diagnostics is done with a vaginal probe, then preparation for the 1st trimester screening will not include filling the bladder.

How the research is done

How is the study for malformations done in the 1st trimester?

It, like the examination of 12 weeks, consists of two stages:

Ultrasound screening during pregnancy. It can be performed both vaginally and through the abdomen. It doesn't feel any different from an ultrasound scan at 12 weeks. The difference is that it is performed by sonologists, who specialize specifically in prenatal diagnostics, using high-class equipment.
Blood sampling from a vein in an amount of 10 ml, which should be carried out on an empty stomach and in a specialized laboratory.

How is the 1st trimester screening diagnostics carried out? First, you have your first pregnancy ultrasound. It is usually performed transvaginally.

Decoding the results

1. Normal ultrasound data

Deciphering the first screening begins with the interpretation of ultrasound diagnostic data. Ultrasound standards:

Coccyx-parietal size (CTE) of the fetus

When screened at 10 weeks, this size is in the following range: from 33-41 mm on the first day of 10 weeks to 41-49 mm on 6 days of 10 weeks.

Screening at 11 weeks - CTE norm: 42-50 mm on the first day of 11 weeks, 49-58 - on its 6th day.

During pregnancy of 12 weeks, this size is: 51-59 mm at 12 weeks exactly, 62-73 mm - on the last day of this period.

2. Thickness of the collar area

1 trimester ultrasound rates for this most important marker of chromosomal pathologies:

at 10 weeks - 1.5-2.2 mm
screening for 11 weeks is represented by a norm of 1.6-2.4
at week 12, this figure is 1.6-2.5 mm
at 13 weeks - 1.7-2.7 mm.

3. Nasal bone

Deciphering an ultrasound scan of the 1st trimester necessarily includes an assessment of the nasal bone. This is a marker, thanks to which it is possible to assume the development of Down syndrome (for this, screening of the 1st trimester is done):

at 10-11 weeks, this bone should already be detected, but its size has not yet been estimated
screening at 12 weeks or one week later shows that this bone is at least 3 mm normal.

4. Heart rate

at 10 weeks - 161-179 beats per minute
at 11 weeks - 153-177
at 12 weeks - 150-174 beats per minute
at 13 weeks - 147-171 beats per minute.

5. Biparietal size

The first screening study during pregnancy assesses this parameter depending on the period:

at 10 weeks - 14 mm
11 - 17 mm
screening for 12 weeks should show a result of at least 20 mm
at 13 weeks BPD is 26 mm on average.

According to the results of ultrasound of the 1st trimester, it is assessed whether there are markers of fetal abnormalities. It is also analyzed to what period the baby's development corresponds. At the end, a conclusion is made whether it is necessary to conduct the next screening ultrasound in the second trimester.

You can ask to have a 1-trimester ultrasound video recorded. You also have every right to get a photo, that is, a printout of the image that is either the most successful (if everything is normal), or most clearly demonstrates the pathology found.

What are the norms of hormones determined by 1 screening

First trimester screening not only evaluates the results of ultrasound diagnostics. The second, no less important stage, by which it is judged whether the fetus has serious defects, is a hormonal (or biochemical) assessment (or a blood test in the 1st trimester). Both of these steps constitute genetic screening.

1. Chorionic gonadotropin

This is the hormone that stains the second strip on your home pregnancy test. If the first trimester screening reveals a decrease in its level, this indicates a pathology of the placenta or an increased risk of Edwards syndrome.

Elevated hCG at the first screening may indicate an increased risk of developing Down syndrome in the fetus. Although with twins, this hormone is also significantly increased.

The first screening during pregnancy: the rate of this hormone in the blood (ng / ml):

10 weeks: 25.80-181.60
11 week: 17.4-130.3
decoding of the perinatal study of the 1st trimester at 12 weeks relative to hCG shows a figure of 13.4-128.5 is normal
at 13 weeks: 14.2-114.8.

2. Pregnancy Associated Protein A (PAPP-A)

This protein is normally produced by the placenta. Its concentration in the blood increases with the duration of pregnancy.

How to understand the data

The program, into which the data of ultrasound diagnostics of the first trimester, as well as the level of the above two hormones, are entered, calculates the analysis indicators. These are called "risks." At the same time, the decoding of the results of screening for the 1st trimester is written in the form not in the level of hormones, but in such an indicator as "MoM". This is a coefficient that shows the deviation of the value for a given pregnant woman from a certain calculated median.

To calculate MoM, divide the indicator of a hormone by the median value calculated for a given area for a given gestational age. MoM norms at the first screening are from 0.5 to 2.5 (with twins, triplets - up to 3.5). The ideal MoM value is close to "1".

Are there risks in research

Normally, the results of the 1st trimester diagnosis end with an assessment of the degree of risk, which is expressed as a fraction (for example, 1: 360 for Down's syndrome) for each syndrome. It is this fraction that reads like this: in 360 pregnancies with the same screening results, only 1 baby is born with Down's pathology.

Deciphering the standards of screening for the 1st trimester. If the child is healthy, the risk should be low and the screening test result should be described as “negative”. All numbers after the fraction must be large (greater than 1: 380).

Poor first screening is characterized by a "high risk" entry in the conclusion, a level of 1: 250-1: 380, and the results of hormones are less than 0.5 or more than 2.5 median values.

If the 1st trimester screening is poor, you are asked to visit a geneticist who decides what to do:

schedule you to retest in the second, then - screening for the 3rd trimester
offer (or even insist) on an invasive diagnosis (chorionic villus sampling, cordocentesis, amniocentesis), on the basis of which the question of whether this pregnancy should be prolonged will be decided.

What affects the results

As with any study, there are false positive results from the first perinatal study. So, for:

IVF: the results of hCG will be higher, PAPP - 10-15% lower, the indicators of the first screening ultrasound will increase the LHR
obesity of the expectant mother: in this case, the levels of all hormones increase, while with low body weight, on the contrary, they decrease
screening for 1 trimester for twins: the rate of results for such a pregnancy is not yet known. Therefore, risk assessment is difficult; only ultrasound diagnostics is possible
diabetes mellitus: the 1st screening will show a decrease in the level of hormones, which is not reliable for the interpretation of the result. In this case, pregnancy screening may be canceled.
amniocentesis: the rate of perinatal diagnosis is not known if the manipulation was carried out within the next week before donating blood. It is necessary to wait a longer period after amniocentesis before undergoing the first perinatal screening of pregnant women.
the psychological state of the pregnant woman. Many people write: "I'm afraid of the first screening." It can also affect the result, and unpredictably.

Some features in pathology

The first pregnancy screening for fetal pathology has some features that doctors of ultrasound diagnostics see. Consider perinatal screening of trisomies as the most common pathologies detected by this examination.

1. Down syndrome

in most fetuses, the nasal bone is not visible at 10-14 weeks
from 15 to 20 weeks, this bone is already visualized, but it is shorter than normal
smoothed out the contours of the face
with dopplerometry (in this case, it can be performed even in this period), a reverse or other pathological blood flow in the venous duct is noted.

2. Edwards syndrome

tendency to decrease the heart rate
have an umbilical hernia (omphalocele)
no visible bones of the nose
instead of 2 arteries of the umbilical cord - one

3. Patau syndrome

almost everyone has heart palpitations
impaired development of the brain
the development of the fetus is slowed down (inconsistency of the lengths of the bones with the term)
violation of the development of some parts of the brain
umbilical hernia.

Where to study

Where is the 1st trimester screening done? Many perinatal centers, medical genetic counseling and private clinics are conducting this study. To choose where to get screening, see if there is a laboratory in or near the clinic. It is recommended to take it in such clinics and centers.

For example, in Moscow, the CIR has proven itself well: it conducts and screening of the 1st trimester can be done in this Center.

Ultrasound screening of the 1st trimester: the average price is 2,000 rubles. The cost of the first perinatal study (with the determination of hormones) is about 4000-4100 rubles.

How much does screening for the 1st trimester cost by type of test: ultrasound - 2000 rubles, determination of hCG - 780 rubles, analysis for PAPP-A - 950 rubles.

If the pregnancy proceeds without complications, the mother feels well, then for the first time she will be able to look at her baby during the first screening at about 12 weeks of pregnancy. We will tell you about what a screening study is at this time in this article.

What it is?

There are three screenings for pregnancy. The very first is recommended by the Ministry of Health to be carried out for a period of 11-13 weeks, 12 weeks are considered optimal. Then the screening study takes place in the second and third trimesters (at 16-24 weeks and at 30-36 weeks).

The examination, which is carried out at the very beginning of the process of carrying a baby, includes Ultrasound, and biochemical blood test for the content of the hCG hormone and the PAPP-A protein. For a number of characteristic markers that are found in the ultrasound diagnostics room, as well as for the concentration of hormones and proteins in the analyzes of a pregnant woman, a preliminary calculation of the risks of a given woman having a baby with incurable and fatal genetic pathologies is made.

This stage of prenatal diagnosis allows us to identify women who are most likely to have a baby with Down syndrome, Turner and Cornelia de Lange syndromes, Patau syndrome, Edwards syndrome, gross neural tube defects, as well as other developmental anomalies that do not leave the slightest chance for a cure. and a normal life.

Previously, screening was carried out only for those pregnant women who belong to the risk group - women who are already 35 years of age or older, who become pregnant from a blood relative, those who have previously had children with genetic problems or women who have relatives with hereditary diseases from your side or from your husband's side. If the expectant mother took medications that are prohibited during early pregnancy, she was also assigned a screening study.

Now this diagnosis is prescribed to all, without exception, the fair sex in an "interesting position." Of course, for personal reasons, a woman can refuse screening, but it is not entirely reasonable to do this, because the examination itself does not oblige anyone to anything.

It should be noted that based on the results of screening during pregnancy at 12 weeks, no one will make any diagnoses. This is not part of the screening study. A woman will only be calculated the individual risks of giving birth to a sick baby, and whether they are healthy can be determined by other methods that will be recommended by an obstetrician and geneticist if the risks turn out to be high.

The first screening is considered the most important and informative. It is carried out free of charge in a consultation at the place of residence, referrals for a blood test and a coupon to the ultrasound office are issued by a doctor to whom the woman registered for pregnancy.

Procedure and preparation

When undergoing a first trimester perinatal examination, it is very important to follow a strict procedure. Ultrasound diagnostics and blood donation from a vein are planned for one day so that the time interval between these two actions is minimal.

Usually, they first undergo an examination in an ultrasound office, and then, with a completed form, go to the treatment room to donate blood. However, in some consultations, the order is reversed. In any case, both examinations are passed strictly in one day.

So that the test results are not affected by negative factors, which include biochemical changes in the blood, the accumulation of gases in the intestines, a woman is recommended carefully prepare for the diagnosis. For two days, you should go on a short diet - do not eat fatty and very sweet foods, fried and smoked, six hours before the blood test, you should not eat at all. A blood test is taken on an empty stomach.

Before an ultrasound scan, a couple of hours should take "Smecta" or "Espumisan" to get rid of intestinal gases, which are faithful companions of pregnancy, since they can put pressure on the pelvic organs and the ultrasound results may be inaccurate.

Ultrasound at 12 weeks is performed with a transvaginal probe; the second way - on the stomach, until it gives a clear picture and an idea of what is happening inside the uterus.

On the appointed day, a woman comes to the office of her obstetrician-gynecologist, is weighed, her height is measured and a detailed questionnaire is filled out. The more data it contains, the more accurately the risks will be calculated. The questionnaire includes data on previous pregnancies, miscarriages, abortions, the woman's age and weight, data on her bad habits (smoking, alcohol), information about her husband and the state of health of close relatives.

Then there will be an ultrasound scan, and then blood donation. The general results will be entered into a single form, a special program will "compare" the genetic portrait of the pregnant woman, along with her analyzes, with the "portraits" of women with great risks of giving birth to a sick baby. As a result, an individual calculation will be issued.

Ultrasound procedure

In the ultrasound office, the doctor will examine the baby, determine if everything is fine with him, in which place of the uterine cavity he is entrenched, and also check the baby for markers that show a high probability of having a child with genetic syndromes. At 12 weeks, the expectant mother will be able to see her child, listen to how his little heart beats, and also see the fetal movements that she does not physically feel yet.

The doctor will definitely indicate in the protocol of the first trimester screening study, how many fetuses are visualized in the uterine cavity, do they show signs of vital activity, and also describe the main dimensions, which will clarify the timing of the "interesting position" and find out how the development of the crumb proceeds.

The indicators of the rate of development at 12 weeks are as follows:

The fetal head circumference (FH) is 58-84 mm, most often 71 mm.

The coccyx-parietal size (CTE) is 51-59 mm, most often 55 mm.

The biparietal head size (BPD) is 18-24 mm, most often 21 mm.

Heart rate (HR) - 140-170 beats per minute.

Motor activity is present.

In addition, the doctor determines the two most important markers for the diagnosis of genetic pathologies - the thickness of the collar space and the presence of nasal bones in the crumbs. The fact is that in children with gross malformations, the cervical fold is enlarged due to the subcutaneous fluid (swelling), and the nose is flattened. He will be able to consider the rest of the facial bones only after one and a half to two calendar months.

TVP (collar space thickness) at 12 weeks in the absence of pathologies does not go beyond the range of 0.7-2.5 mm. If this parameter is slightly exceeded in the baby, the expectant mother may be advised to undergo an ultrasound scan again in a week. If the TVP significantly exceeds the upper limits of the norm, additional examination will be required, the risks of giving birth to a sick baby increase. We are talking about an excess of 3.0 mm and more.

It can be much more difficult to see the nasal bones, they are not always visualized at 12 weeks, the fetus can sit with its back to the doctor's sensor and stubbornly not want to turn around and let its nose be measured. If it was possible to do this, the normal values of the length of the nasal bones at this time are considered to be values that do not go beyond the range of 2.0-4.2 mm.

If the doctor indicated that at 12 weeks these bones are not visualized or their size is less than 2 mm, the program that calculates the risks will increase the individual likelihood of having a baby with Down syndrome, Turner, Patau syndrome.

In fact, a baby may just have a small miniature nose, which is still difficult to capture numerically, especially on an old ultrasound scanner with a low image definition.

Theoretically, at 12 weeks, you can already try to determine the sex of the child, because the external genitals are formed, and if the baby is conveniently located and open to the gaze of the diagnostician, it may well be noticed. However, one should not expect guarantees from the doctor that a boy or a girl will be born. Sex at this time can only be named presumably (the probability of an accurate hit is approximately 75-80%). More precisely, the doctor will assess the baby's sexual characteristics at the next ultrasound scan, after 16-17 weeks of pregnancy.

In addition, at the end of the first trimester, an ultrasound scan evaluates the probable threats of interruption of gestation - thickened uterine walls can indicate the presence of hypertonicity, as well as the condition of the cervix, fallopian tubes, and cervical canal.

Blood chemistry

In the analysis of the venous blood of a pregnant woman, the laboratory assistant detects the amount of hCG hormone and plasma protein PAPP-A contained in it. Because only two blood components are assessed, the first screening test is called a “double test”. The results of this study, in contrast to the ultrasound data, which are given to a woman immediately after the passage, will have to wait from several days to several weeks - it depends on how long the queue is lined up for research in an accredited medical genetic laboratory.

What numbers will be as a result of the analyzes, one can only guess, since individual laboratories use their own norms in the calculations. To simplify the decoding, it is customary to talk about the norm of PAPP-A and hCG in MoM - a value that is a multiple of the median. In a healthy pregnancy, when both the child and the mother are doing well, both values "fit" in the range from 0.5 to 2.0 MoM.

Fluctuations from this range up or down give rise to a lot of experiences in pregnant women and many possible reasons:

Increasing hCG."Overkill" on this indicator can be a sign of Down syndrome in a baby, as well as a sign that a woman is carrying more than one child. The two fetuses together give a practical double increase in the hormone rate. Increased hCG may be found in a woman who is overweight, edema, toxicosis, diabetes and hypertension.

Lowering hCG. An insufficient level of this hormone, inherent only in pregnant women, is characteristic of the development of Edwards syndrome, and can also indicate the likelihood of a miscarriage or a delay in the development of the baby.

Lowering the PAPP-A. A decrease in plasma protein in the sample sometimes indicates the development of conditions such as Down, Patau, Edwards, Turner syndromes. Also, an insufficient amount of this substance often speaks of malnutrition of the baby, that the baby is deficient in nutrients and vitamins that it needs for normal development.

Raising PAPP-A. The increase in protein in the sample is not of great diagnostic value in terms of calculating the possible risk of chromosomal abnormalities. This indicator may be higher than normal with twins or triplets, as well as with a tendency to a large fetus.

How are risks calculated?

The results of analyzes and ultrasound, as well as all available information about the health of the pregnant woman and her age are loaded into a special program. Thus, the calculation of the individual risk is carried out by the machine, but the result is double-checked by a person - a geneticist.

By a combination of factors, the individual the risk may look like a ratio of 1: 450 or 1: 1300 for each disease. In Russia, the risk is considered high 1: 100. The threshold risk is 1: 101 - 1: 350. Thus, if a pregnant woman was counted the probability of having a baby with Down syndrome 1: 850, this means that one in 850 children has women with identical health indicators , age and other criteria will be born sick. The rest 849 will be born healthy. This is a low risk, no need to worry.

Women for whom screening diagnostics at 12 weeks shows a high risk for a particular genetic disease are recommended additional diagnostics, since the screening itself cannot be considered a basis for a final verdict, it is not that accurate. A non-invasive DNA test can be done. Such an analysis costs several tens of thousands of rubles and is done exclusively in medical genetic centers and clinics.

If the analysis confirms the suspicions, then you still have to go for an invasive test.

Amniocentesis or chorionic biopsy can be offered immediately, without spending time and money on examining the baby's blood cells isolated from the mother's blood, as is done with a non-invasive DNA test. However, both biopsy and amniocentesis involve penetration into the membranes to collect material for analysis. The procedure is carried out under the supervision of an ultrasound scan only by experienced doctors, but the risk that the fetus will become infected, the outpouring of water, and the termination of pregnancy still remains.

Agreeing or not agreeing to undergo an invasive examination at high risks is a private matter for every woman, no one can force her to do it. The accuracy of the analysis is 99.9%. If disappointing assumptions are confirmed, the woman is given a referral to terminate the pregnancy for medical reasons. It is also up to the woman and her family to decide whether to interrupt it or not.

With the onset of pregnancy, a woman begins to worry about many questions. Each expectant mother wishes her baby a normal formation and development. In the early stages, there may be risks of developing certain diseases of the embryo. To study the condition of the baby, doctors prescribe screening for 1 trimester. The standards for ultrasound (a photo of the survey carried out is usually attached) a woman can find out from the specialist who observes her.

What is Perinatal Screening?

Perinatal screening involves a study of a pregnant woman to identify various defects of the child at the stage of intrauterine development. This method includes two types of examination: biochemical blood test and ultrasound examination.

The optimal period for such a survey has been determined - this is a period from ten weeks and six days to thirteen weeks and six days. There is a certain standard for screening ultrasound of the 1st trimester, with which the results of the examination of a pregnant woman are compared. The main task of conducting ultrasound at this time is to identify serious and identify markers of chromosomal abnormalities.

The main anomalies are:

the size of the TVP - the thickness of the space of the collar zone;
underdevelopment or absence of the bones of the nose.

Ultrasound during pregnancy reveals signs of a disease such as Down syndrome, and some other pathologies of fetal development. The screening rate (ultrasound) of the 1st trimester should be analyzed before 14 weeks. After this period, many indicators are no longer informative.

Screening of the 1st trimester: standards for ultrasound (table)

To make it easier for the doctor to determine the condition of a pregnant woman, there are certain tables of indicators for the development of the baby's organs. The ultrasound protocol itself is drawn up in a structured way so that the dynamics of the formation and growth of the embryo is clear. The article presents the standards of screening for the 1st trimester.

Decoding an ultrasound scan (the table is given below) will help to obtain information about whether everything is in order with the fetus.

Determination of the viability of the embryo

To assess the viability of the embryo, it is very important to look at the heartbeat in the early stages. In a small person, the heart begins to beat already in the fifth week of being in the mother's womb, and it can be detected using screening for the 1st trimester (ultrasound standards) from seven weeks of fetal life. If at this time the heartbeat is not detected, we can talk about the likelihood (of a frozen pregnancy).

To assess the viability of the embryo, the heart rate is also taken into account, which normally, for a period of six weeks, ranges from 90 to one hundred and ten beats per minute. These important indicators of screening for the 1st trimester, ultrasound rates, together with the study of blood flow and body length, should correspond to the reference data for the gestational age.

The more modern equipment is used for examination, the better you can see all organs and get the most accurate results. If there is a high probability of the presence of congenital defects or genetic developmental abnormalities, then the pregnant woman is sent for a deeper examination.

In some regions, when registering with antenatal clinics, screening of the 1st trimester is mandatory for all pregnant women. The standards for ultrasound may not coincide with the results obtained, so doctors immediately take the necessary measures to preserve the life and health of the child or mother. But most often, pregnant women who are at risk are sent for such an examination: these are women from thirty-five years old, those who have genetic diseases in the family and in children born earlier, have miscarriages in previous pregnancies, stillborn children or non-developing pregnancies. Close attention is also paid to expectant mothers who have undergone viral diseases at the beginning of pregnancy, take dangerous medications or are under the influence of radiation.

If a woman has spotting in the first trimester, then an ultrasound scan makes it possible to reveal the degree of the child's viability or his death.

Dates of pregnancy

An additional examination to determine the exact duration of the state of pregnancy is indicated for women who have an irregular menstrual cycle or do not even know approximately the date of conception of the child. For this, in most cases, 1 trimester screening is used. Norms for ultrasound, decoding of the main indicators and the date of conception do not require special medical knowledge. The woman herself can see the expected date of birth, the gestational age and the number of embryos. Basically, the number of weeks, determined using ultrasound, corresponds to the period that is calculated from the first day of the female cycle.

During the study, the doctor makes control measurements of the size of the embryo. With the data obtained, the specialist compares the screening rates of the 1st trimester. Ultrasound is decrypted according to the following parameters:

measuring the distance between the sacrum and the crown of the embryo (7-13 weeks), which makes it possible to determine the real gestational age according to special tables;
measuring the length of the head of the unborn child (after 13 weeks), this is an important indicator in the second half of pregnancy;
determining the size of the longest - the femur of the body of the embryo, its indicators reflect the growth of the child in length (at 14 weeks), in the early stages it should be approximately 1.5 cm, and by the end of gestation it should increase to 7.8 cm;
measurement of the circumference of the child's abdomen - indicates the size of the embryo and its estimated weight;
determination of the head circumference of a ripening fetus, which is also used to predict the natural birth of a child. Such a measurement is carried out even in the last stages of pregnancy, according to which the doctor looks at the size of the small pelvis of the future woman in labor and the head of the child. If the head circumference exceeds the parameters of the pelvis, then this is a direct indication for a cesarean section.

Definition of malformations

With the help of ultrasound in the first weeks of pregnancy, various problems in the development of the child and the possibility of curing him before birth are revealed. For this, an additional consultation with a geneticist is prescribed, who compares the indicators obtained during the examination and the screening rates for the 1st trimester.

The transcript of an ultrasound scan may indicate the presence of any malformations of the child, but the final conclusion is given only after a biochemical study.

Screening of the 1st trimester, ultrasound standards: nasal bone

In an embryo with chromosomal abnormalities, ossification occurs later than in a healthy one. This can be seen as early as 11 weeks when the 1st trimester screening is performed. The standards for ultrasound, the decoding of which will show whether there are abnormalities in the development of the nasal bone, help the specialist determine its size starting from 12 weeks.

If the length of this bone does not match the gestational age, but all other indicators are in order, then there is no cause for concern. Most likely, these are the individual characteristics of the embryo.

The value of the coccygeal-parietal size

An important indicator of the development of a little man at this stage of pregnancy is the size from the coccyx to the crown of the head. If a woman had irregular menstruation, the gestational age is determined by this indicator. The norm for ultrasound screening for the 1st trimester of this indicator is from 3.3 to 7.3 cm for a period of ten to twelve weeks, inclusive.

Collar space thickness (TVP)

This indicator is also called the thickness of the cervical fold. It has been noticed that if the embryonic TBP is thicker than 3 mm, then there is a risk of Down syndrome in the child. The values used by the doctor are shown by the screening of the 1st trimester. The norms for ultrasound (the thickness of the collar space) are considered very important for the further monitoring of a pregnant woman.

Determining the location of the placenta

The baby's place (placenta) is necessary for the intrauterine blood supply to the little person. It is needed to provide it with food. Ultrasound makes it possible to determine abnormalities in the development and position of the placenta. If it is too low in relation to the fundus of the uterus, this is called placenta previa, which can lead to blockage of the exit for the baby during labor.

It is good to show the location of the child's place by ultrasound screening of the 1st trimester. The norms of such research reject low placenta previa. But even if it is located close to the bottom of the uterus, doctors are in no hurry to sound the alarm, as it can rise with the course of pregnancy. But if the position of the placenta has not changed at a later date, then the following problems are possible:

the placenta can obscure the cervix and prevent natural childbirth;
since the lower part of the uterus is stretched, the placenta can exfoliate from it and cause severe bleeding (detachment of the placenta).

Examination of the yolk sac

On the 15-16th day of pregnancy, from the day of conception, the formation process is underway. This "temporary organ" of the baby is examined by doing an ultrasound scan (screening of the 1st trimester). Terms and norms for should show its presence and size. If it has an irregular shape, enlarged or reduced, then the fetus may have died.

The yolk sac is an appendage that sits on the ventral side of the embryo. It contains a supply of yolk necessary for the normal development of the baby. Therefore, it is very important to check what is the standard for screening ultrasound of the 1st trimester in comparison with the parameters of the study, it is very important to monitor the course of pregnancy. Indeed, at first (while the child's organs do not function independently), this appendage performs the function of the liver, spleen, and is also used as a supplier of primary germ cells that are actively involved in the formation of immunity and in metabolic processes.

The role of biochemical blood tests

Examining the state of the embryo, the doctor looks not only at the results of ultrasound (screening of the 1st trimester). The norms in it are as important as in the blood test. Such an analysis, in addition to an ultrasound examination, is carried out to determine at what level specific proteins (placental) are located. The first screening is done in the form of a double test - to detect the level of 2 protein species:

"PAPP-A" - the so-called pregnancy-related plasma protein A.
"HCG" - free

If the levels of these proteins are changed, then this indicates the possible presence of various chromosomal and non-chromosomal abnormalities. But identifying an increased risk does not mean that something is definitely wrong with the embryo. Such results of screening for the 1st trimester, transcript, ultrasound rate indicate that it is necessary to more closely monitor the course of pregnancy. Often, repeated testing no longer shows the risk of genetic diseases.