A fertilized egg is a round or ovoid (egg-like) formation that surrounds the embryo, usually located in the upper half of the uterine cavity.
In the early stages of pregnancy (in the first trimester), ultrasound is performed to establish the localization (location) of the ovum. On ultrasound, the ovum looks like a small dark gray (almost black) spot with clear contours.
The presence of the ovum in the uterine cavity eliminates the possibility of an ectopic pregnancy. In multiple pregnancies, two separate ovules can be seen.
At what stage of pregnancy can you see the fertilized egg?
Approximately two and a half weeks after conception, with a delay of menstruation of 3-5 days or more, that is, in the fourth to fifth obstetric week of pregnancy from the last day of the last menstruation, the ultrasound diagnostician can already see the ovum in the uterine cavity using transvaginal ultrasound. The diagnostic level of hCG in the blood serum, at which the ovum should be visible in the uterine cavity with transvaginal ultrasound, is from 1000 to 2000 IU.
The ovum looks like a round-shaped black (anechoic or echo-negative, that is, does not reflect ultrasonic waves) formation, the diameter of which is very small and ranges from 2-3 mm. The embryo and extraembryonic organs are still microscopic and therefore not yet visible with ultrasound. Using a parameter like average inner diameter of the ovum most expedient in the first 3-5 weeks of pregnancy from conception, when the embryo is not yet visible or is difficult to identify. The measurement error is usually less than 6 days.
The size of the ovum by weeks of pregnancy
The size of the ovum by week is a very important indicator during pregnancy. For example, the diameter of the ovum of 3 mm corresponds to a gestation period of 4 weeks, and the diameter of the ovum of 6 mm corresponds to the 5th week of pregnancy. The increase in the average diameter of the ovum occurs in the early stages of pregnancy at a rate of approximately 1 millimeter per day.
Most of the normative indicators of the average inner diameter of the ovum are limited to a period of 8-10 weeks. This is due to the fact that after 6-7 weeks of pregnancy, the size of the ovum cannot reflect the growth of the embryo. Since its appearance, the coccygeal-parietal size of the embryo (CTE) is used to estimate the duration of pregnancy.
The sizes of the average inner diameter of the ovum by week are given in the calculator.
Irregularly shaped fertilized egg (deformed fertilized egg)
If the ovum is located in the uterine cavity, then such a pregnancy is called a physiological uterine pregnancy. The fertilized egg up to 5-6 weeks, normally on ultrasound, has a round or drop-shaped shape, surrounded by a thin shell. By 6-7 weeks, it completely fills the uterine cavity and acquires an oval shape in the longitudinal scan, and a rounded shape in the transverse one. If on an ultrasound, the doctor sees a deformation of the ovum (it is elongated, flattened from the sides, looks like a bean), then this can indicate the tone of the uterus... A change in the shape of the ovum is possible with partial detachment. A significant deformation with fuzzy contours is observed with a frozen pregnancy.
Timely diagnosis of deformity of the ovum during pregnancy makes it possible to save the child.
Empty fetal egg
Normally, the ovum in the uterine cavity is visible with transvaginal ultrasound approximately 32-36 days after the first day of the last menstruation. An important place is given to yolk sac, which is of great importance in the development of the ovum. In the physiological course of pregnancy, the yolk sac has a rounded shape, liquid content, reaches its maximum size by 7–8 weeks of gestation.
The embryo looks like a thickening along the edge of the yolk sac. The image of a normal embryo with a yolk sac looks like a "double bubble". By seven weeks, the yolk sac is 4-5 mm in size. The relationship between the size of the yolk sac and the outcome of pregnancy has been established. When the diameter of the yolk sac is less than 2 mm and more than 5.6 mm at 5-10 weeks, spontaneous miscarriage or miscarriage is often observed.
The absence of a yolk sac with an average inner diameter of the ovum of at least 10 mm is an unfavorable ultrasound criterion for the threat of termination of pregnancy.
An empty (false) fertilized egg is an accumulation of fluid, usually of an irregular shape, located near the border of the endometrium.
Sometimes there are cases when the ovum has the usual shape and size, but inside it there is no yolk sac or the embryo itself. The chorion of the empty ovum produces the hormone hCG, as in a normal physiological pregnancy, so pregnancy tests will be positive. An ultrasound scan performed early in pregnancy can be erroneous, since the earlier it is done, the less chance of seeing the embryo. Up to 7 weeks of pregnancy, a re-examination is required to clarify the diagnosis.
When on ultrasound they see a fertilized egg in the uterine cavity, but do not see the embryo itself, doctors call this pathology anembryony (without embryo).
Non-developing pregnancy (death of the embryo) is evidenced by the following signs: altered fetal membranes, the absence of an embryo when the size of the ovum is more than 16 mm in diameter or the absence of a yolk sac when the membranes are more than 8 mm (when carrying out transabdominal ultrasound: 25 mm - without an embryo and 20 mm - without yolk sac); uneven contours, low location or absence of a double decidual sac.
In the early stages, the cause of pregnancy fading is most often chromosomal abnormalities that arose during fertilization.
Of course, one of the most beautiful times in a woman's life is carrying a baby and waiting for his birth. However, everything is not always smooth.
Recently, the fairer sex is increasingly faced with various problems associated with the reproductive system. One of the worst situations that a woman can face during pregnancy is without an embryo. This pathology, like any other disease, has its own causes, symptoms and various diagnostic methods. Such a defect must necessarily undergo medical correction, since it will not lead to the birth of a child, and the decomposition of an undeveloped ovum in the uterine cavity can lead to serious complications and long-term treatment afterwards.
How it all starts
When a woman is planning a pregnancy, she cannot even imagine a fertilized egg without an embryo. However, often the fairer sex has to deal with this problem.
At the time of ovulation, the female cell leaves the follicle - the place of its development. Heading to the uterine muscle through the fallopian tubes, it meets the male reproductive cell. At this moment, the sperm merges with the egg, as a result of which a zygote is formed. Continuously dividing and multiplying, the cells move towards the uterus, where they are firmly attached to the walls for all subsequent months of pregnancy. With normal development and proper growth of the embryo, a happy couple will see their baby after forty weeks of pregnancy.
The attachment of the ovum can occur both to the front wall of the uterus and to the back. This will not affect the course of pregnancy and the birth of a baby.
Possible pathologies
During pregnancy, various situations can arise when the state of the embryo is incompatible with life. Let's consider the most common ones.
For example, if the ovum is attached outside the uterine cavity, then this is called an ectopic pregnancy. This condition can pose a threat to the life of a woman, therefore, it should be diagnosed and corrected as early as possible.
Also, a woman may have an arbitrary miscarriage for one reason or another. In this case, the lady also needs urgent medical attention.
Another pathology is a fetal egg without an embryo. This condition has recently appeared quite often. Out of a thousand pregnant women, one hundred do not have an embryo.
Anembryony
Such a diagnosis can be made to a woman when the ovum develops and grows for weeks, but does not have an embryo.
Under the influence of certain factors, cell division stops at a certain level, and the embryo stops growing. In this case, its size is so small that even an ultrasound machine cannot fix it. Then the doctor announces to the woman this terrible diagnosis: a fertilized egg without an embryo.
There are also cases when the embryo not only stopped its development at the very initial stages, but was completely absent. Then the pregnant woman is also diagnosed with anembryonia. With this type of pathology, the ovum by weeks may not meet the deadline or develop and grow without content.
Fetal egg without embryo: why is this happening?
The reasons for the development of anembryonia are still not fully understood. However, there are several prerequisites that can provoke the death of an embryo in the early stages of its growth.
Bad habits
This point includes nicotine addiction, excessive consumption of alcoholic beverages. Harmful destructive substances enter the fetus through the blood of the expectant mother and have an irreversible effect on it, as a result of which development stops.
Genetic abnormalities
A fetal egg without an embryo may be due to initial abnormalities in cell division after fertilization. In this case, the woman is unable to influence the situation and somehow warn herself against such a pathology. It is also possible to develop a similar defect if fertilization occurred with cells of a blood relative.
Hormonal Disorders
When stopped, the size of the ovum usually does not correspond to the date. The reason for this may be a lack or excess of certain hormones in the female body. A child can only be taken out by the fair sex in whose body the production of hormones is in perfect order.
Fetal egg without an embryo: signs of pathology
At the initial stage of the development of pathology, a woman does not experience any discomfort. With the development and growth of the ovum, a certain hormone is produced in a pregnant woman. Under his influence, a woman experiences all the "delights" of pregnancy. She may be tormented by morning sickness, intolerance to certain odors, the desire to eat something "such". The absence of an embryo in an egg does not affect these signs in any way. Therefore, a woman may be unaware of anembryony to the last.
For some of the fair sex, the opposite is true. The body, realizing that the state of the embryo is not compatible with life, begins to reject the ovum. At this point, the pregnant woman may feel pain in the lower abdomen, as well as observe red or brown discharge from the genitals.
Diagnosis of pathology
If a woman is not worried about any symptoms, then she learns about anembryonia at the next examination using an ultrasound sensor. The doctor discovers that the size of the ovum is out of date.
If there are signs of the beginning of the termination of pregnancy, then usually the woman herself turns to a specialist. To begin with, the obstetrician-gynecologist conducts a physical examination and notes the condition of her neck. After that, the patient is assigned to an ultrasound study. The doctor fixes the ovum on the screen - how it looks, what size it has - and notes the absence of an embryo.
If a woman doubts the competence of the doctor, then she may be re-examined in a few days. In this case, it is necessary to take into account the intensity of the discharge and exclude bleeding. If repeated diagnostics also shows a fertilized egg without an embryo - a photo of an empty ring can be seen on the screen - then there is no doubt about the assumption of anembryony.
After a diagnosis is made, a woman needs medical correction.
Treatment of anembryonia
There are two ways to correct this pathology.
Drug treatment
If the gestational age has not reached six weeks, then the patient may be offered. In this case, the woman drinks the necessary medicine under the supervision of a doctor and waits for the cramping pains to begin. The contents of the uterus are rejected and released.
The patient should be under the supervision of a doctor for several more days, until the final completion of bleeding. Next, the woman is examined by a doctor using an ultrasound sensor and determines the purity of the uterine muscle.
Surgical intervention
In most cases, doctors choose this particular method of treatment, since during it you can thoroughly clean the inner cavity of the uterus without developing complications.
The doctor puts the patient to sleep using general anesthesia and begins the procedure. This manipulation lasts from five to twenty minutes. With the help of special instruments, the gynecologist scrapes out the upper uterine layer with the pathological ovum. Within a few hours after carrying out such a manipulation, a woman can be discharged.
After the completion of bloody discharge, an ultrasound scan is necessary to make sure that there are no parts of the ovum left in the uterus.
Clarification of the cause of the pathology
The material obtained after the cleaning is always sent by the doctor to It is there that they find out whether there was an embryo at all, how long it stopped developing, and what caused this.
Recovery
After the treatment, the patient is always prescribed anti-inflammatory and antibacterial drugs. If you have hormonal problems, you may be advised to take restorative drugs.
Conclusion
During pregnancy, you need to be especially careful about your well-being. Find out what a fertilized egg is, what it looks like and what it is for.
For any symptoms of the absence of an embryo in the ovum, consult a doctor for advice. Take care of your health!
The concept of fetal ultrasound is somewhat limited by the term and does not convey a complete understanding of the scope of the study. In addition to the ovum, doctors analyze a fairly large amount of information about the course of pregnancy.
As a rule, after confirming the fact of pregnancy with a household test and a delay in menstruation, the expectant mother has an emotional explosion. After independent actions, mommy takes a trip to the gynecologist, which ends with a referral to an ultrasound scan and tests.
A fetal ultrasound is performed early to establish that the fertilized egg has attached itself to the right place, which is the uterine cavity, and nothing threatens its development.
Ultrasound diagnostics, carried out transvaginally, makes it possible to observe the ovum in the uterine cavity from the fifth week.
The fetal egg on ultrasound is normally round or oval, having smooth walls, and has a smooth outline. This structure is located in the uterus, namely in its day. Due to the decidual reaction, a smooth echogenic rim of no more than 2 mm thick is formed around the ovum. The sign of a double decidual ring appears at a period of five to six weeks.
The inner contents of the ovum remain anechoic until a certain point, namely before the yolk sac can be visualized. It is a specific formation located in the inner region of the ovum. Such an object can be detected for a period of about 5 weeks, provided that the SVD (average inner diameter) is about 13 mm.
After the diameter of the yolk sac reaches 3–6 mm, during examination it is possible to find the actual embryo of the unborn baby! A truly magical sight is the way the embryo joins the yolk sac through the Vitelin duct: this sight on the ultrasound machine resembles a ring on which a small diamond is planted.
The term embryo itself is used when the pregnancy is 5-10 weeks.
It is possible to detect an embryo starting from 5 weeks of pregnancy, subject to certain conditions:
- examination with transvaginal access
- fetal development is proceeding normally
- the average inner diameter of the ovum should be 25 mm.
What does it mean if the fertilized egg is not found?
There may be several reasons for this. The survey may be too early (less than 5 weeks). In addition, if no fertilized egg is found, this could mean a likely ectopic pregnancy. In this case, it is necessary to control the level of a special hormone secreted by the embryo - chorionic gonadotropin (hCG). If the fertilized egg is not found anywhere, the doctor can make a special diagnosis - pregnancy of unknown localization.
What exactly can be seen on a fetal ultrasound?
Often expectant mothers meet with the abbreviation SVD. This abbreviation stands for the average indicator of the inner diameter. This indicator can take on different values throughout the entire development of the fetus. CTE (coccygeal-parietal size) and SVD are assessed in early pregnancy using the Robinson and Fenning formulas.
At five and a half weeks, the gynecologist performing the ultrasound will show the mother the beating heart of the embryo. It should be noted that the CTE (coccygeal-parietal size) of the future baby can only be no more than seven millimeters.
Fetal ultrasound should be performed during the 1st screening from 11 weeks to 13 weeks of six days.
The expectant mother must definitely go for an ultrasound examination if complications of pregnancy were found.
Is there any reason to undergo this procedure often?
Reasons for dynamic (regular) follow-up fetal ultrasound:
- benign neoplasms;
- detachment of the ovum, associated or not with the chorionic platform;
- death of the embryo;
- cysts, chorionic or amnion formation;
- pathology of the chorion of the expectant mother: its detachment or underdevelopment;
- multiple pregnancy;
- insufficient development of the embryo;
- a clear discrepancy between the menstrual and obstetric timing of pregnancy;
- Cystic formations in the uterus and ovaries;
- pathologically underdeveloped amniotic cavity;
- pathologies of the uterus, such as, for example, two-horned, bipartite;
- fetal heart rhythm disturbance (bradycardia and tachycardia).
What is assessed with a fetal ultrasound?
Anembryony
Quite often, doctors find that the yolk sac and the embryo are absent in the space of the ovum. This kind of pathology is called anembryonia.
Taking into account the fluctuations in ovulation in different women, the diagnosis of anembryonia is made with caution. The accuracy of such a diagnosis is highly dependent on the class of equipment and the qualifications of the doctor conducting the study.
If anembryonic disease is suspected, doctors should begin to observe the expectant mother in dynamics, conducting regular examinations.
CTE estimate
Another common abbreviation is KTR. It stands for coccygeal-parietal size. Doctors-diagnosticians must evaluate the increase in CTE without fail. The normal dynamics for this indicator is a daily increase of at least 0.7 millimeters.
Amniotic cavity
Another important parameter when conducting ultrasound examination is the visualization of the amniotic cavity. This cavity on the device is a hypo - or anechoic cavity, the difference in media of which looks like a thin echogenic closed radially strip, which is slightly thinner than the wall of the yolk sac. In case of normal pregnancy, when visualizing this object, heartbeats in the embryo are always recorded!
An embryo growth of less than 0.2 mm per day, the absence of one of the extraembryonic structures are a prognostically unfavorable factor. Patients with identified disorders are sent for a more thorough examination. After such examinations, they can be referred for an abortion.
Already from the ninth week of pregnancy, diagnosticians have the opportunity to detect during the study the future placenta - chorion, which is a villous membrane that is located outside the ovum. It is this formation that turns a little later into the fruiting part of the future placenta.
On an ultrasound machine, the chorion looks like a highly echogenic formation. This formation has a semicircular structure, also having wavy contours, and is located along the outer edge of the ovum.
The shape and condition of the ovum
In some cases, the ovum may change its shape, but this will not be a sign of pathology, for example, it may occur due to an increase in the uterine tone. It is worth noting that an oval-shaped ovum is probably evidence of a growing threat of spontaneous miscarriage, if a hematoma is observed behind it, there is usually a history of bleeding from the vagina and pulling pain in the lower abdomen.
Detachment of the ovum is visualized as follows: anechoic strip around the ovum It can have a cavity completely free of additional echostructures, or it can be with echogenic contents - a sign of hemorrhage or its long term. The length of the detachment and its connection with the chorionic site will also be established.
The same picture is with the detachment of the chorion, with the difference that the detachment zone and the presence of hematomas of the retrochorial zone are established. A hematoma with the ingress of blood between the membranes of the ovum is possible. Treatment should definitely take place in the gynecological department of the hospital.
As a result of the detachment, we can expect its complete disappearance, regression and involution of the hematoma and prolongation of pregnancy; options with complete detachment and loss of pregnancy up to 11 weeks are not common with proper obstetric management of such pregnant women.
Low location of the chorion
Also, for a period of up to 11 weeks with placentation on the anterior wall of the uterus, one can often observe such a pathology as a low location of the chorion (future placenta). Critical is the complete presentation of the chorion, the ingrowth of its villi into the scar, which may be located on the anterior wall of the uterus. The following tactics are recommended: regular follow-up examinations and an extremely careful attitude towards pregnancy, which consists in excluding physical activity and sexual intercourse.
For an accurate diagnosis of such a pathology as placenta previa, the ultrasound doctor will try to get the clearest picture of the area around the internal os of the cervix. Preparation for such an ultrasound examination will consist in a slight filling of the bladder.
Ultrasound examinations used to evaluate uterine scar after cesarean section and other surgeries are controversial. It makes no sense to predict how the myometrium will behave, it is strictly individual. Therefore, the assessment of the viability of the scar is the prerogative of obstetricians delivering childbirth.
However, it must be borne in mind that the attachment of the placenta to the postoperative scar is a delivery by Caesarean section.
"Implantation window"
Sometimes an early visit by a future mother to a specialist in prenatal diagnostics ends in disappointment. There is a so-called "implantation window" when a woman has a delay in her period, while the ovum did not descend into the uterine cavity.
It is this period, when it is not known where the ovum is located, that gives a lot of experiences.
A good option is a visually confirmed pregnancy (fetal egg) in the uterine cavity.
Ectopic pregnancy
There is also a violation of the implantation of the ovum, for example, when it is delayed on the way outside the uterine cavity, i.e. with an ectopic pregnancy.
In order to talk about an ectopic pregnancy, it is necessary to detect the fetal heartbeat outside the uterine cavity and the presence of a fetal egg.
Options for such incorrect implantation:
- development of the embryo in one of the sections of the fallopian tubes,
- right or left,
- at the place where the fallopian tube enters the uterine cavity,
- in the uterine scar after a previous cesarean section,
- in the cervix,
- in the abdominal cavity,
- in the ovaries.
In addition, diagnosing incorrect implantation and ectopic pregnancy is not an easy task, and even expert-level equipment does not guarantee adequate reliability. Typically, an ectopic pregnancy is hidden among the adhesions around the fallopian tube. The echo picture of an ectopic pregnancy of tubal localization is a cystic small inclusion, tubular-annular in the projection of the ampullary, isthmic and interstitial or fimbrial (rarely) parts of the right or left fallopian tube, with blood flow or already visible fetal heartbeat.
Treatment is carried out in a hospital setting, in foreign clinics it is possible to administer a special solution of Methotrexate, in Russia - the operative removal of the ectopic ovum, with the possibility of preserving the reproductive function of the affected section of the tube.
If an ectopic pregnancy is in a scar or cervix, it cannot be saved, an operation to remove it, an abortion is pending.
There are cases of multiple pregnancies, when one ovum is in the uterine cavity, and the second is in the isthmus or scar on the uterus after an operative delivery (Caesarean section). Here, pregnancy is also not possible to preserve.
Malnutrition
A decrease in the volume of amniotic fluid leads to a sequencing of oligohydramnios. This pathology can serve as a reason for careful observation to exclude, first of all, fetal kidney abnormalities. In addition, impaired placentation can also be a cause for oligohydramnios.
A small number of amniotic fluid can lead to lung hypoplasia and fetal compression. In turn, compression of the fetus can be the result of a violation of the position of the limbs and dislocations. Moreover, compression of the fetus can lead to pathological changes in the face, including flattening and low position of the auricles.
Bubble drift
Bubble drift is another formidable complication that can occur in the early stages; is an abnormal proliferation of the outer layer of cells of the embryo, tending to fill the entire uterine cavity. Traditionally, complete (transformations affect the entire area of the fetal membrane) and partial (changes cover part of the membrane) are distinguished. Moreover, there is a more severe form of the disease - a destructive cystic drift; in which ultrasound reveals in the uterus exclusively small-cystic mixed echogenicity of the mesh structure tissue in the absence of the fetus.
Other pathologies
An early ultrasound scan will help identify formidable defects that are incompatible with life in embryos. Perfect ultrasound equipment and the latest data processing technologies allow you to see early abnormalities in the formation of organs in an embryo. Leading companies such as GE, PHILIPS, HITACHI help ultrasound doctors.
The diagnosis in this case is likely to be determined when the following factors are found:
- abnormal position of the limbs,
- stiffness of body movements with a reduced or completely non-existent response to acoustic stimulation,
- growth retardation of the embryo,
- polyhydramnios or low water.
Alarming signals such as swelling of the soft tissues of the head, deformities of the chest, gastroschisis, microcephaly, hypoplasia or aplasia of the extremities can also be detected.
Modern medicine has gone far ahead, and the latest breakthrough, which is rapidly gaining popularity, is 3D ultrasound, in which it becomes possible to detect pathologies that were simply impossible to diagnose earlier. However, on any device, the study should be carried out by a high-class diagnostician.
If, during the examination of a woman on an ultrasound machine, a fetal egg is found in the uterine cavity, the specialist ascertains the onset of pregnancy. By the size and shape of the formation, the doctor can determine the gestational age and possible problems with the bearing of the fetus. What does a fertilized egg look like? What should it be at different times after conception?
The concept of the ovum and its role in the body of a pregnant woman
A fertilized egg is a structure that forms after the fusion of an egg and a sperm cell, transforming into a fetus and amniotic membranes. First, 2 cells are formed, then 4, 8, etc. They are transformed into a zygote, then into a blastocyst, an embryo. On the 7-10th day, the formed ovum is introduced into the uterine cavity.
The fertilized egg performs the following functions:
- preserves the developing fetus;
- provides the embryo with the necessary nutrition;
- supports blood circulation of the growing embryo at an early stage of development;
- fixes the future fetus in the uterine cavity;
- forms amniotic membranes;
- creates the basis for the formation of the placenta;
- activates the production of the pregnancy hormone - hCG.
What does it consist of and what does it look like?
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The fertilized egg looks like a small oval body. As you can see in the photo, the formation color is dark. This multi-component education consists of the following elements:
- Chorion is the outer shell of the ovum, which performs a protective function. It has villi that facilitate the attachment of the embryo to the uterine cavity. Subsequently, the chorion is converted to the placenta.
- Amnion is the inner layer of the ovum membrane. Produces a nutrient medium for the embryo - amniotic fluid.
- Yolk sac. Located between the above elements in the area where the future placenta grows together with the baby's umbilical cord. It resembles a yellow pea. The bag provides nutrition for the embryo in the first stage of development.
- The embryo. In the first weeks, it is not visualized. It can be seen after 6 weeks of pregnancy.
Diagnostic methods, indicators studied during ultrasound
There are several ways to determine the characteristics of the ovum:
- Manual inspection. With this method, the doctor calculates the size of the embryonic sac, focusing on the size of the uterus. To determine the parameters of the uterus, the gynecologist feels the woman's vagina and abdominal cavity. The method has a large error, since the doctor cannot determine how many embryos are developing in the uterine cavity. If twins are expected, then the size of the genital organ is larger than in a singleton pregnancy.
- Ultrasound procedure. Ultrasound allows you to most reliably find out the parameters of the ovum. The membrane can be seen at 4 obstetric weeks of gestation, when it reaches 1 mm. Upon reaching a diameter of 3 mm, the yolk sac is visible. The study reveals: the average inner diameter of the ovum (SVD), its shape, place of attachment, the presence of detachment, the presence of an embryo, the size of the yolk sac.
- Blood test for hCG. HCG begins to be produced from the moment the embryo is implanted. When the embryo is attached to the uterus (on day 7), its level reaches 150 U / L. In the future, its concentration increases. Since there are norms for hCG and the size of the embryo for the duration of pregnancy, the size of the ovum is established. However, the necessary parameters are determined in this way only approximately, since the standards for hCG have a fairly large take-off (for example, at 3-4 weeks - from 1.5 to 5 thousand U / L), and with twins, the level of the hormone increases.
Parameters of the ovum are normal by week of pregnancy
The size of the ovum by week is of great diagnostic value until 7-10 weeks of gestation, when the embryo is poorly visible. After 12-14 weeks, it acquires the status of a fetus, and the placenta begins to form, their indicators are monitored. The shell of the fruit grows rapidly. Up to 15-16 weeks, it grows by 1 mm per day. For example, at 9 weeks, its diameter is 35 mm, and at 11 - more than 47 mm. The table shows what should be the SVD of the ovum from 4 to 13 weeks.
| Term, weeks | Diameter at the beginning of the week, mm | Diameter at the end of the week, mm | Yolk sac size, mm |
| 4 | 1 | 4 | - |
| 5 | 5 | 11 | - |
| 6 | 11 | 18 | 3 |
| 7 | 19 | 26 | 4 |
| 8 | 27 | 34 | 4,5 |
| 9 | 35 | 43 | 5 |
| 10 | 44 | 50 | 5,1 |
| 11 | 50 | 56 | 5,5 |
| 12 | 56 | 62 | 6 |
| 13 | 62 | 67 | 5,8 |
As can be seen from the table, the diameter increases from 1 mm in 14 days to 17–18 mm, and after another 7 days it reaches 20–24 mm. In this case, the coccygeal-parietal size of the fetus is informative only from 8 weeks.
Possible deviations of the ovum at different stages of development of the embryo and fetus and their causes
Normally, the shell of the fetus is convex and has clear edges. For a successful pregnancy, it must be attached in the upper part of the uterine cavity. If abnormalities are detected during the ultrasound scan, the doctor develops tactics for the further management of pregnancy. When planning events, the size of the ovum is necessarily taken into account.
Deviations from standard sizes, growth retardation
If for a period of 5-6 weeks, when the embryo is poorly visible, it is revealed that the ovum is more than normal, the woman may have twins. To confirm the assumptions, the expectant mother is given a referral for a second examination after 7 days and hCG tests. However, if there is only one fetus in the shell, a large egg is a sign of pathology. A downward discrepancy is also an alarming signal. Possible reasons for deviations are presented in the table.
| Non-compliance with standards | What caused it? | Causes | Forecast |
| Diameter lags behind growth rates by 2 weeks or more |
|
| Spontaneous or medical abortion |
| The membranes develop more slowly than the embryo | If the growth retardation is more than 14 days, hypoplasia of the ovum is diagnosed. | ||
| SVD is significantly higher than normal |
|
| Abortion |
Particular attention is paid to the size of the ovum after the IVF procedure. To control the dynamics of a woman after IVF, an ultrasound is prescribed. Optimal is 28 DPP. At this time, the parameters of the fetus should correspond to 5 obstetric weeks.
Non-standard form of the ovum
The ovum acquires a non-standard shape with strong tension in the uterus. If the reproductive organ is tense, the fetal membrane is stretched in length or has a flattened shape. In this case, the doctor recommends taking measures to eliminate the uterine tone. If there are pulling pains in the lower abdomen and spotting, treatment is carried out in a hospital.
The non-standard form of the ovum, combined with a developmental delay, indicates the onset of a spontaneous abortion. In this case, it makes no sense to keep the pregnancy.
Wrong position
Anchoring the embryo below the upper third of the uterus requires careful monitoring by doctors. The low position of the embryo in the early stages does not pose a threat to gestation. There is a great risk that the ovum will rise higher as the uterus grows. However, attachment at the cervix indicates the development of a "cervical" ectopic pregnancy. In this case, the embryo is removed.
The concept of an empty ovum in the early stages
Up to 5 embryonic weeks, the embryo is invisible inside the ovum. However, at 5-6 weeks from the moment of conception (or at 7 obstetric week) the embryo should be found. If this does not happen, it is recommended to do an ultrasound scan after a week. In the absence of an embryo in the shell at the 8th week of pregnancy, the formation of an empty egg in the uterine cavity is noted.
When a woman has a serious delay in critical days, the gynecologist sends the patient for an ultrasound scan to confirm or deny the presence of pregnancy. First of all, the doctor looks at the contents of the uterus, whether there is a fertilized egg in it.
Why is the presence of the ovum important?
A fetal egg found by ultrasound in the uterine cavity is the first confirmation of a healthy uterine pregnancy. At the same time, the thoroughly studied sizes of the ovum by week allow you to find out the exact timing of pregnancy, as well as predict the further course of pregnancy.
From the beginning to the middle of the first trimester, the ovum is one of the main indicators of the good development of the embryo. Since the size of the ovum grows by weeks of pregnancy, its size and filling may indicate a successful pregnancy, possible problems, and even a frozen pregnancy.
How is the presence of a fertilized egg determined?
A gynecologist by examination on a chair and palpation can only assume the presence of a fetal egg in the uterus, based on an increase in the size of the organ. Namely, the doctor can see the ovum only with the help of an ultrasound machine.
As a rule, in the early stages, a transvaginal ultrasound is performed, it gives the most accurate results, since with this method of diagnosis, the uzist can get as close as possible to the object under study.
Fetal egg - what is it?
A fertilized egg is an accumulation of a mass of cells resulting from the fusion of an egg and a sperm cell and further division
The shape of the cell mass can be round or oval, but cases of deformation are not excluded. As a rule, diagnosticians look closely at unusual forms; more frequent observations of the development of the embryo are not excluded in such situations. But it's not worth talking about any problems with the unusual shape of the egg, since the matter may be in tone caused by the ultrasound machine itself. By removing the apparatus for a while or by lowering the pressure, the uzist can see that the shape has changed and returned to normal.
How does a fertilized egg appear
The mass of cells travels for some time along the fallopian tube, heading to the uterus and the place of its future implantation. A week after the fertilization happened, the fertilized egg attaches to any convenient wall of the uterus, using the villi located on the outer shell of the egg, destroying the micro-part of the uterine mucosa and vascular walls during implantation. All the time of the travel and formation of the ovum, the cells feed on substances from the ovum, after which nutrients will begin to flow from the placenta.
At 3 weeks from conception, the size of the ovum seriously increases, since from the set of cells introduced into the wall of the uterus, a "baby's place", in other words, the placenta, begins to grow. In it, the fetus will live, feed and develop until the very birth.
The size of the ovum will increase again at 5 weeks of gestation. At this time, it will already be possible to examine the embryo inside the egg. It is worth noting that if at this time the uzist did not see the embryo in the ovum, then there is still no talk of a frozen pregnancy and cannot be, since the discrepancy in the growth periods of the ovum is large enough and can reach two weeks.
The thing is that it is impossible to determine the exact timing of pregnancy with natural conception due to the fact that a woman's ovulation can take place on different days of the cycle, fertilization can also be delayed, attachment can take place faster or slower. Therefore, the timing of pregnancy is set on the basis of the beginning of the last critical days, which is an obstetric period, not an embryonic one, and if the embryo is not visible inside the egg at the 5th week of pregnancy, the ultrasound is repeated again after two weeks. Most often, on repeated ultrasound, the embryo is already visible.
Sizes by week
It is not necessary that the size of the ovum by week coincides absolutely exactly with the standards. Possible error reaches two weeks. In some cases, for example, with late ovulation, the error may be even greater, the ovum may have a larger or smaller diameter and this will be the norm, but only under the condition of normal further development of the embryo.
Here are the sizes of the ovum by week for ultrasound:
- Until the 5th week of pregnancy, the ovum is very small, by the end of the fifth week it reaches 18 millimeters, and the volume is 2187 millimeters cubed, but in the fourth week it has a diameter of only 7 millimeters. If the egg has a small diameter, then this also indicates a short period after conception.
- Already at the 6th week, the size reaches 22 millimeters.
- At 7 weeks, the size of the ovum is already 24 millimeters.
- In the following weeks, the growth of the ovum takes place abruptly, at the eighth week of pregnancy it will already be 30 millimeters, in the future the egg will grow by an average of 6-8 millimeters weekly.
- By the 13th week, the diameter will already reach 65 millimeters, and the volume will be equal to 131,070 millimeters cubed.
The growth of the ovum
The size of the ovum by week also gives an idea of the size of the embryo hiding in the egg. Each week, the embryo develops as rapidly as its house, while the sizes of the embryo and egg correspond to:
- At 5 weeks, the coccygeal-parietal size is 3 millimeters.
- At 6 weeks already 6 millimeters.
- At the 7th week, it grows up to 10 millimeters.
- At 8 weeks, not only the CTE is estimated, but also the biparietal size, namely the estimated width of the embryo's head, CTE at this time is 16 millimeters, and the BPR is already 6.
- From 9 to 13 weeks, the embryo grows on average by 10-13 millimeters weekly, and by the end of the first trimester, its growth reaches 66 millimeters. The width of the head also grows all this time, at 9 weeks - 8.5 millimeters, at 10 - 11, at 11 - 15 millimeters, at 12 - 20 and at 13 it already reaches 24 millimeters.
It is also worth paying attention to the fact that in the weeks between the main screenings, the size of the egg and the parameters of the embryo may not be so perfectly verified, therefore, for screening indicative studies, weeks are allocated when the fetus in all its indicators approaches the average, in the first trimester, for example , this is 11-14 weeks of pregnancy. Before the first screening, at about the 9th week of pregnancy, the uzist and the gynecologist check the ratio of the size and the presence of a heartbeat in the fetus, in accordance with these data, adjustments can be made at the expected timing of pregnancy.
How many fetal eggs can there be
Depending on how many eggs are fertilized at the same time or in a short period of time, one or more fetal eggs appear.
As a rule, if we are talking about twins, that is, about the fertilization of one egg in which two embryos were born, then the fertilized egg is one and it divides into two parts closer to the moment of attachment to the wall of the uterus or does not split at all. In all other cases, with multiple pregnancies, there will be as many fertilized eggs as there are fertilized eggs, that is, two or more. In conditions of multiple pregnancies, the size of the ovum by week will differ slightly from the standards, since the development of the pregnancy itself is a little more complicated, the distribution of nutrients and space in the uterus also takes place differently.
Fetal egg and artificial insemination
Special attention should be paid to the fact that with the advent of such methods for fertilization as IVF, multiple pregnancies, with the development of several fetal bladders at once, have become much more.
With artificial insemination, everything happens a little differently, since an already fertilized fertilized egg with an age known to doctors is inserted into the uterus, therefore the size of each fertilized egg usually exactly corresponds to the embryonic period and may not correspond to the gestational age.
All transcripts of ultrasound about the size of the ovum and embryo should be found out directly from the uzist who performed the diagnosis, as well as from a personal gynecologist, since only they will be able to correctly assess absolutely all indicators, taking into account the specific features of pregnancy.