The fetus is 9 mm, how long does it last? Dimensions and pathologies of the ovum

In early pregnancy, an ultrasound is performed to identify a viable embryo in the uterine cavity, confirm the gestational age, exclude pathology of the embryo, or identify normal variants, such as multiple pregnancies.

The initial sign of pregnancy is thickening of the endometrium, but ultrasound does not tell what exactly causes this thickening.

Using a high-resolution transvaginal transducer, a gestational sac with a diameter of 1 mm is visualized in the uterine cavity 4 weeks and 2 days after the last menstrual period during a regular menstrual cycle.

If menstruation is delayed for 5-7 days or more (gestational age is 5 weeks), a fertilized egg with a diameter of 6 mm should be clearly visible in the uterine cavity. It has a clear round shape with a fuzzy light rim along the periphery (hyperechoic rim - chorion). In this case, the level of beta-hCG in the blood is 1000-1500 IU/l (see What is hCG?). When the hCG level is more than 1500 IU/l, the fertilized egg in the uterine cavity should be clearly visualized.

With a lower level of hCG, the fertilized egg in the uterine cavity may not be detected by transvaginal echography. With a transabdominal examination, detection of the fertilized egg in the uterine cavity is possible at a beta-hCG level of 3000-5000 IU/l.

Fig.1Uterine pregnancy 4-5 weeks. Transabdominal scanning.

IMPORTANT: The gestational age cannot be accurately determined by the size of the fertilized egg. Many tables on the Internet with the size of the fertilized egg determine the period very approximately (see table below).

From about 5.5 weeks, transvaginal ultrasound begins to visualize an extraembryonic structure in the fetal egg - the yolk sac (eng. yolk sac). At the same time, the beta-hCG level averages approximately 7200 IU/l (see hCG norms during pregnancy).

Since the yolk sac is part of the embryonic structures, its detection makes it possible to distinguish a fertilized egg from a simple accumulation of fluid in the uterine cavity between the endometrial layers, and in most cases, makes it possible to exclude an ectopic pregnancy. The incidence of ectopic pregnancy is 1-2 per 2000-3000 pregnancies. Its risk increases with the use of assisted reproductive technologies (ART). It is necessary to suspect an ectopic pregnancy when the hCG level is more than 1500 IU/l, and the fertilized egg is not detected in the uterine cavity.

Fig.2Pregnancy 5.5 weeks. The yolk sac is identified. Transvaginal scan.

From 6 weeks of pregnancy (sometimes a little earlier), an embryo about 3 mm long can be identified in the fertilized egg. From this same period, most ultrasound machines can detect the heartbeat of the embryo. If the heartbeat is not detected or is unclear when the embryo length (CTE) is 5 mm, a repeat ultrasound scan is indicated after a week. The absence of cardiac activity at this stage is not necessarily a sign of fetal distress or a non-developing pregnancy.

The numerical values ​​of the heart rate in an embryo during an uncomplicated pregnancy gradually increase from 110-130 beats/min at 6-8 weeks of pregnancy to 180 beats/min at 9-10 weeks.

The length of the embryo is measured from the head to the tail end, and is designated under the term CTP (coccygeal-parietal size), in English. literature - CRL (Crown-Rump Length). It should be noted that the coccygeal-parietal size of the embryo is less subject to individual fluctuations than the average internal diameter of the ovum, and therefore, its use to determine the gestational age gives better results. The error usually does not exceed ±3 days. With clear visualization of the embryo, the gestational age is determined depending on its length, and not on the size of the average internal diameter of the ovum (SVD).

To correctly measure the coccygeal-parietal size of the embryo, its clear visualization is necessary. In this case, one should strive to measure the maximum length of the embryo from its head end to the tailbone.

During normal pregnancy, the diameter of the ovum increases by 1 mm per day. Lower growth rates are a poor prognostic sign. With a gestation period of 6-7 weeks, the diameter of the ovum should be about 30 mm.

Table 1. Dependence of gestational age on the average internal diameter of the ovum (Dv), M. N. Skvortsova, M. V. Medvedev.

Table 2. Normal values ​​of the coccygeal-parietal size (CPR) depending on the gestational age (full weeks + days), data in millimeters, the lower limit is the 5th percentile, the upper limit is the 95th percentile.

It should be emphasized that determining the gestational age by the length of the CTE is best done before 12 weeks of pregnancy. At a later date, measurements of biparietal diameter, head and abdominal circumference should be used.

Fig.3 Pregnancy 12 weeks 3 days.

The motor activity of the embryo is determined after 7 weeks of pregnancy. At first, these movements are very weak and isolated, barely noticeable during examination. Then, when differentiation into the head and pelvic ends of the embryo becomes possible, movements resemble flexion and extension of the body, then separate movements of the limbs appear. Since episodes of motor activity of the embryo are very short and count in seconds, and periods of motor rest can be significant in time, registration of the cardiac activity of the embryo is undoubtedly a more important criterion for assessing its vital activity.

The diagnosis of anembryonia (empty fertilized egg) is assumed if a yolk sac is not detected in a fertilized egg measuring 20 mm. Or if the fertilized egg with a diameter of more than 25 mm with a yolk sac does not contain an embryo. And also when the yolk sac size is 10 mm or more. In any case, if anembryonia is suspected, all data obtained should be interpreted in favor of pregnancy, and the study should be repeated after 7 days.

The diagnosis of a non-developing pregnancy should not be made if, on ultrasound, the ovum is less than 20 mm in size. When the embryo is 5 mm or more in length, in most cases the heartbeat should be clearly detectable. If the embryo is less than 5 mm, the ultrasound should be repeated after a week. If, upon repeated examination a week later, at CTE = 5-6 mm, cardiac activity is not detected, the pregnancy is not viable. The diagnosis of a non-developing pregnancy can be confirmed by a discrepancy between the beta-hCG level and echographic data.

It should be noted that the normal rate of pregnancy termination in the population is 15-20% of all clinically diagnosed pregnancies. However, in reality, if we count all “chemically” diagnosed pregnancies, determined by the level of beta-hCG before the expected next period, the miscarriage rate can reach up to 60%.

Sincerely, ultrasound diagnostics doctor, Barto Ruslan Aleksandrovich, 2012

All rights reserved®. Quoting only with the written permission of the author of the article.

What is SVD during pregnancy and how to determine it on ultrasound? There is only one answer to this question.

SVD is the average internal diameter of the ovum according to ultrasound diagnostics. This indicator is measured exclusively in millimeters.

Fertilized egg illustration

The gestation period is characterized by certain values ​​of the internal diameter. The digital value of the SVD constantly varies, so the period is calculated with an error of a week to a week and a half. A more reliable sign for clarifying the gestational age using ultrasound is the CTR (coccygeal-parietal size) indicators. It should be noted that the coccygeal-parietal size of the embryo is less subject to individual fluctuations compared to the average internal diameter of the ovum, and therefore is used more often to establish a reliable gestation period. The error is approximately three days.

When the fetus is well visualized, the period is determined by the length of the fetus, and not by the internal diameter. The coccygeal-parietal size is recorded during a routine ultrasound and reflects the actual size of the fetus in combination with the approximate weight of the fetus. As a rule, measurement of CTE indicators is used up to 12 weeks of gestation, and in later ultrasound studies, the biparietal diameter of the circumference of the head and abdomen of the fetus is used.

Approximate indicators of SVD, depending on the timing of gestation

• When the diameter of the ovum is approximately 4 millimeters, the gestation period is no more than 5 weeks. It is possible to assume that about four weeks have passed since conception.
• Closer to the fifth week, the diameter will reach 6 millimeters.
• After a few days, the fetus becomes 7 millimeters.
• By the end of the 6th week, the diameter increases to 12 - 18 millimeters.
• The average value of SVD at a period of six weeks and five days is 16 millimeters.

Fertilized egg on ultrasound

Of course, the expectant mother is concerned about the following question: how intensively does the fetus grow in the second and third trimester? We can say with confidence that until 15 - 16 weeks, its diameter grows by one millimeter every day. Then its value increases by an average of 2 - 2.5 millimeters every day. During the border period of 16 - 17 weeks, they stop measuring the internal diameter of the fetal egg, focusing on more reliable indicators.

Ultrasound examination at short gestation

Diagnostics are carried out for the following purposes:

Diagnosis of the localization of the ovum

1. Establishing the exact location of the fetus (in the uterine cavity or outside it). When the fetus is located outside the uterus, we are talking about ectopic pregnancy. When the fetus cannot be visualized or the recognition process becomes significantly more difficult, they resort to precise determination of the embryo’s heartbeat. Signs of fetal viability may be found in the fallopian tubes or abdominal cavity.

In addition to this complication, other complications may appear in the initial stages of pregnancy: for example, a changed shape of the fertilized egg; improper attachment; high risk of placental abruption and other pathological disorders.

2. Determining a single or multiple pregnancy is not difficult. In the uterine cavity there are two or more fetuses with active life activity.

3. Assessing the main dimensions of the fertilized egg and embryo and comparing them with normal values.

4. Study of the correct structure of the embryo and fertilized egg to exclude serious congenital developmental anomalies. These may be chromosomal mutations (for example, Down syndrome).

5. Vital signs are assessed based on the presence of a heartbeat, which is detected already in the fifth week of gestation. The motor activity of the embryo is quite well determined after the seventh week of gestation.

At the initial stage, the movements are so weak and isolated that they can hardly be distinguished during an ultrasound. As the embryo grows, motor activity begins to resemble characteristic flexion and extension movements, and then active movements of the upper and lower extremities. Since individual moments of motor activity are quite short in time and are calculated in seconds or their fractions, the definition of cardiac activity is used to register the fact of fetal life.

6. Detection of a corpus luteum in one of the ovaries. This small cystic formation provides the expectant mother’s body with important hormones to preserve the fetus in the early stages of development.

7. The study of amnion and chorion comes down to their ratio depending on the period of gestation already in the first trimester. Based on the obtained ultrasound results, it is possible to predict the further course and outcome of pregnancy.

Ultrasound is indispensable for determining possible problems with pregnancy

8. Diagnosis of a threatened miscarriage using ultrasound allows one to recognize early symptoms, which are characterized by a clear thickening of one of the walls of the uterine cavity, as well as a significant increase in the internal os. In case of a possible miscarriage, ultrasound assesses the vital signs of the fetus and the condition of the uterus and placenta as a whole.

9. Diagnosis of diseases and possible malformations of the female genital area (anomalies of the vagina or uterus). Any deviation from the norm determines the course and outcome of pregnancy.

Typical signs and features of fertilized egg implantation

Often, the fertilized egg attaches to the wall of the uterus several days after unprotected sexual intercourse, and then the egg is implanted into the endometrial layer after fertilization. From this moment on, the woman’s body begins to actively produce the hormone hCG (human chorionic gonadotropin), to which the pregnancy test strip reacts.

Implantation of fertilized egg

The screening test will not always be positive, so it is necessary to resort to a reliable blood test to determine hCG. After receiving a positive test result, you must immediately contact a gynecologist at the antenatal clinic for registration and further observation for nine months.

A formed fertilized egg is the surest sign of pregnancy. It has a characteristic oval shape and is quite well visualized on ultrasound in the third week of absence of menstruation.

The embryo itself can only be seen when the period reaches the fifth week. If the ultrasound doctor does not detect an embryo in the fertilized egg, then the study is repeated after about half a month. As a rule, the embryo becomes more clearly visible, and its heartbeat is also detected. In other cases, we are talking about pathological development or even a frozen and undeveloped pregnancy.

That is why it is very important to undergo an ultrasound to exclude possible complications for further correction of the situation. The first trimester is the most important period of gestation, since throughout its entire duration all the organs and systems of the unborn baby are actively formed.

Timing of routine ultrasound diagnostics

Based on the results of the WHO, strict periods have been defined for conducting mandatory ultrasound examinations during the gestation period of the unborn baby.

Three ultrasound screenings are required

At other time intervals, the examination is prescribed strictly according to individual indications from the mother and fetus:

• The first ultrasound examination is recommended to be carried out at 12 - 14 weeks;
• the second screening is prescribed at 20 - 24 weeks;
• The third ultrasound visit is necessary at 32 - 34 weeks of gestation.

It is not advisable to neglect the timing of the next examination, since it is during the specified period of gestation that it is possible to recognize fetal malformations. And if a forced need arises, an interruption for medical reasons. The last screening examination can also be carried out at a later time.

The results of the current diagnostics may be significantly outside the normal range, but this is far from a cause for concern. Do not forget that the development of each child has its own characteristics. However, you should not ignore the identified symptoms either.

Fetus

Pregnancy is a physiological condition in which a new organism develops in the uterus, resulting from fertilization. Pregnancy lasts on average 40 weeks (10 obstetric months).

The growth of a child, the formation of its organs and systems occurs naturally during various periods of intrauterine development, which is subject to the genetic code embedded in the germ cells and fixed in the process of human evolution.

Photo pixabay.com

Pregnancy begins from the moment fertilization- fusion of a mature male cell (sperm) and a female egg.

After a few hours, the fertilized egg begins to divide exponentially and descends through the fallopian tube into the uterine cavity (this journey takes up to five days).

As a result of division, a multicellular organism is formed, called Morula, which is implanted into the wall of the uterus on the 7th day.

The villi of the outer cells of the embryo connect with the blood vessels of the uterus, subsequently forming from them placenta. Other outer morula cells give rise to development umbilical cord and membranes.

Over time, various tissues and organs of the fetus will develop from the internal cells.

You can get detailed information about the development of the fetus, the formation of its organs and systems for each week of pregnancy in the topic fetal development by week

fertilized egg

fertilized egg is an embryo with embryonic membranes at an early stage of development. By 4-5 weeks of pregnancy, the fertilized egg is the size of a walnut and is located in the uterus in the form of a polyp, then, as the pregnancy progresses, it fills the entire uterine cavity.

Information The size and growth of the ovum are assessed during an ultrasound examination. The main indicator is average internal diameter of the ovum, which can be used to approximately determine the duration of pregnancy.

A table of normal indicators of the fetal egg SVD, as well as possible types of pathology (detachment, deformation, empty egg) are in the topic fertilized egg.

Dimensions

One of the important tasks of ultrasound is to determine the biometric indicators of the fetus:

1. Coccyx-parietal size up to 20 weeks;
2. Length and estimated weight of the fetus;
3. Abdominal and fetal head circumference;
4. Fronto-occipital and biparietal dimensionsheads;
5. Length of femur and tibia bones;
6. Length of the upper arm and forearm bones.

These data are important for assessing fetal development, compliance with the expected gestational age, and also for determining delivery tactics. The normal values ​​of these indicators, depending on the stage of pregnancy, can be found in the topic measuring the size of the fetus during ultrasound examination.

If the size of the fetus lags behind normal indicators, characteristic for a given stage of pregnancy, it can be assumed intrauterine growth retardation.

Fetal hypotrophy can occur at any stage of pregnancy (usually in the third trimester) and is a serious disease that, if left untreated, can lead to fetal death.

You can learn more about the causes, classification, symptoms, diagnosis and treatment of this pathological condition in the topic intrauterine growth retardation.

If the size of the fetus, on the contrary, is ahead of the indicators, then we can assume the birth of a large baby weighing more than 4 kg. In this case, it is necessary to resolve the issue of the possibility of childbirth through natural means.

Heartbeat

Heartbeatfetus is an equally important indicator of the normal development and condition of the fetus, therefore control over the work of the child’s heart is carried out constantly throughout pregnancy and childbirth.

The main methods of listening to the fetal heartbeat are:

1. Auscultation(listening to the fetus using a special tube - a stethoscope);
2. Cardiography (CTG);
3. Echocardiography(EchoCG).

Detailed information about the above research methods, as well as about normal heart rate indicators and abnormalities, is contained in the topic fetal heartbeat.

Movements

Motor activity in the fetus appears quite early ( at 7-8 weeks of pregnancy). From 10-11 weeks movements become more conscious, the child develops a swallowing reflex. At this time, the fetus is still very small in size and practically does not touch the walls of the uterus during movement, so a woman cannot feel movement at such a time.

Photo pixabay.com

It is believed that during the first pregnancy a woman begins to feel the first movements of the child at 20 weeks, and during the second and subsequent pregnancies - at 18 weeks.

However, these are average statistics; in reality, it all depends on individual sensitivity and other factors. For example, slender women who lead an active lifestyle begin to feel the baby’s movements earlier.

Thus, The first movements felt by the mother may appear between 16 and 24 weeks of pregnancy.

Detailed information about the first movements of the fetus, norms of motor activity and methods for counting the movements of the child can be found in the topic of fetal movements.

Location

AdditionallyData on the location of the fetus are necessary to determine the woman’s delivery tactics. A normal course of labor is possible with the correct position and presentation of the baby.

In the first half of pregnancy, the fetus is small and moves freely in the uterus. Closer to 34-35 weeks it begins to take a stable position, which in most cases persists until childbirth. At this stage, the doctor leading the pregnancy can already decide on the method of childbirth: natural or by cesarean section.

The topic of fetal position and presentation reveals in detail the types of position and presentation, the causes of malposition of the child, possible complications of pregnancy and childbirth, and you can also learn about a set of gymnastic exercises that promote fetal inversion.

Determining the sex of the child

Determining the sex of a child in utero is possible using ultrasound and invasive procedures (chorionic villus sampling and amniocentesis).

There are also many different folk methods for determining gender (calendars, blood group tables, omens, etc.), but the effectiveness of these methods is extremely low.

Information about these methods, as well as possible errors in determining gender, is contained in the topic of determining the sex of a child.

Placenta

Placenta (“baby place”) is an embryonic, temporarily existing organ that carries out communication and metabolism between the mother’s body and the fetus.

The formation of the placenta begins in the second week pregnancy, when the embryo implants into the wall of the uterus. Within 3-6 weeks its intensive development is underway and 12-16 weeks During pregnancy, the placenta is already formed and begins to perform its functions. The functions, as well as data on its normal sizes, degrees of maturity and location are presented in the topic placenta.

Premature abruption of the normally located placenta (abbreviated as PONRP)– this is its premature separation before the birth of the child (during pregnancy or childbirth). You can learn more about this pathological condition, its clinical picture, classification, complications and management of pregnancy and childbirth in the topic: premature abruption of a normally located placenta.

ImportantPlacenta previa is a pathological condition in which the placenta is located in the lower part of the uterus and completely or partially covers the internal os.

In the third trimester of pregnancy, placenta previa occurs in 2-3% of women. In the second trimester, during an ultrasound, a low position of the baby's place can be detected more often. This is due to the phenomenon of placenta migration: as the uterus grows, the placenta moves upward and takes a normal position.

This pathological condition is extremely dangerous for the mother and fetus and requires immediate hospitalization of the woman. For more information, see the topic placenta previa.

Premature aging of the placenta – this does not correspond to the degrees of maturity of the placenta for a given stage of pregnancy.

Maturation of the placenta is a physiological process associated with the need to ensure the development of the fetus in a timely and complete manner.

During ultrasound they evaluate degree of maturity of the placenta and their correspondence to the gestational age, which can be found in the topic of premature aging of the placenta. This topic also provides information about the clinical manifestations, complications and treatment of this pathology.

Amniotic fluid

Amniotic fluid(amniotic fluid) is a biologically active liquid medium that is located inside the membranes, surrounds the fetus and plays an important role in ensuring its vital functions.

The main methods for studying amniotic fluid include:

1. Ultrasound;
2. Amnioscopy;
3. Amniocentesis.

These methods are used for determination of the following indicators amniotic fluid:

1. Color, transparency;
2. Quantity;
3. hormones;
4. Cytological and biochemical composition.

Detailed information about normal indicators of amniotic fluid and research methods can be obtained in the topic amniotic fluid.

An important indicator is the amount of amniotic fluid. A decrease or increase in the amniotic fluid index indicates the development of a pathological condition that can lead to a number of complications during pregnancy and childbirth. Information about this pathology of amniotic fluid is contained in the topics oligohydramnios and polyhydramnios.

Source: http://baby-calendar.ru/plod/

fertilized egg

If a doctor, during an ultrasound examination, reports that he sees a fertilized egg in the uterine cavity, the woman can be congratulated, because in 9 months she will become a mother. The presence of a fertilized egg can be determined already on the 7-9th day of missed menstruation.

If the fertilized egg is in the uterus, then the pregnancy is normal, uterine. The specialist will immediately determine the size of the fertilized egg, its shape and location. In addition, he will pay special attention to whether there is a detachment or other pathological conditions.

What does a fertilized egg look like?

The fertilized egg is an oval or round body with a diameter of several millimeters. The diameter of the ovum is measured during the first ultrasound. Taking into account its size, a specialist can determine the gestational age. But in some cases the error in determination is 1-1.5 weeks. Therefore, when trying to establish a period, the doctor also takes into account indicators of the coccygeal-parietal size.

At 3-8 weeks of pregnancy

the fertilized egg looks like a formation in the form of a ball or oval. Already at 5-6 weeks, the yolk sac, which provides nutrition to the embryo and performs a hematopoietic function in the early stages of embryonic development, is similar to a bubble inside the cavity of the fertilized egg.

The size of the fertilized egg at this stage of pregnancy is from 1.5 to 2.5 centimeters. It is already possible to examine the embryo at this time. It looks like a five-millimeter strip located next to the yolk sac. And although it is not yet possible to determine which structure and part of the embryo, the heartbeat is already being recorded.

At this time, the baby’s heart beats at a frequency of 150-230 beats per minute.

In addition, the neural tube is already forming in the fetus, and the cells distribute “responsibilities” among themselves, who will create which organs.

By the end of the 7th week, the embryo has already acquired its characteristic shape in the form of the letter C. At this time, it has already detached from the surface of the fertilized egg. An ultrasound can already distinguish the head, torso and tiny rudiments of arms and legs. An already formed umbilical cord is visible in the fertilized egg.

Irregular shape of the fertilized egg

The normal shape of the fertilized egg is oval or round. If it is flattened on the sides and looks like a bean, this may indicate the tone of the uterus. This condition should be monitored by a doctor.

If nothing bothers the woman, then the deformation does not pose a threat to the pregnancy.

In case of increased uterine tone, doctors prescribe a set of measures (bed rest, medication) to relieve hypertonicity and return the fertilized egg to its correct shape. This can be achieved by relaxing the muscles of the female reproductive organ.

But, if the fertilized egg has an irregular shape, and the woman experiences pain, discharge or symptoms of cervical dilatation, urgent measures must be taken. In such cases, the woman is assigned to the inpatient department of the hospital for safekeeping.

An incipient abortion is called abruption of the ovum. In this case, premature rejection of the fertilized egg from the uterine wall is observed.

Important note: when a spontaneous abortion begins, timely assistance is very important, because, in most cases, the pregnancy can be saved. The main thing is to do everything quickly and competently.

Detachment is accompanied by nagging pain in the lower abdomen, pain in the lower back, and dark red and sometimes brown discharge.

The reasons that cause detachment of the ovum include ovarian dysfunction, various diseases of the woman (tumors, inflammatory processes, infectious diseases), underdevelopment of the genital organs of the expectant mother, severe toxicosis, excessive physical activity, and stress. But the most obvious cause of detachment of the ovum is a lack of progesterone, which is often called the pregnancy hormone.

If a pregnant woman shows signs of abruption of the ovum, she (or relatives) should urgently call an ambulance and call the obstetrician-gynecologist to inform him about what happened. Until the ambulance team arrives, the woman should lie down and raise her legs up. You can rest them against the wall or put them on the back of the sofa.

Detachment of the ovum is dangerous because it can lead to abortion or missed abortion. Therefore, at the slightest suspicion of detachment, you need to seek medical help.

At a very early stage, the embryo in the fertilized egg is not yet visible, and this is the norm. But from five weeks the embryo should already be visualized. If the embryo is not visible, a repeat examination is scheduled after 1-2 weeks. If this time there is neither an embryo nor a heartbeat, they speak of anembryony. In this case, the woman needs to cleanse.

You need to know that even if the ovum is empty, the pregnancy test will still be positive. This is due to the fact that certain mechanisms have been launched in the body, in particular, a special “pregnant hormone” - human chorionic gonadotropin - has begun to be produced.

The reason for the absence of an embryo in the fertilized egg, in most cases, is a failure at the genetic level. Also, anembryonia can be triggered by taking certain medications that are strictly prohibited during pregnancy.

If a woman is diagnosed with an “empty ovum,” which was confirmed by a repeat ultrasound examination, then there is no chance of pregnancy this time.

Then the woman is given the necessary manipulations, prescribed treatment and sent for rehabilitation.

Many women need not only physical, but also psychological rehabilitation to cope with the feelings and emotions that arise as a result of loss.

It is recommended to plan your next pregnancy at least six months later.

Especially for beremennost.net Olga Rizak

Source: http://beremennost.net/plodnoe-yaitso

Fertilized egg sizes by week: periods of fetal development during pregnancy

· You will need to read: 6 minutes

The embryo and the membrane that surrounds it is the fertilized egg. As the embryo grows, the size of the fertilized egg increases over the weeks, which can be observed during examination using ultrasound. But it should be remembered that the accuracy of studies in the early stages of pregnancy is low, and when diagnosing a woman, the possibility of error cannot be ruled out.

Formation of the fertilized egg

The first stage of the cycle that a reproductive cell goes through is the release of the egg from the follicle. Usually 3-4 follicles mature, but only one egg passes through a woman’s fallopian tubes during ovulation.

The growth and development of a new life begins with the fusion of an egg and a sperm. Immediately after ovulation and fusion, a protective membrane forms around the egg. This outer protective layer around the embryo will later develop into the amniotic sac containing amniotic fluid.

In the early stages of pregnancy, during an ultrasound, you can see the formation of an ovoid shape of small diameter. This is the fertilized egg. The first stage of its development is the morula, consisting of 12-32 blastomeres formed as a result of division of the zygote, which turn into a compact ball.

As the cells multiply, the embryo continues to move through the fallopian tubes until it attaches to the mucous wall inside the uterus.

After this, the outer layer of the membrane begins to produce hCG (chorionic gonadotropin hormone), which is one of the first indicators of a woman’s pregnancy. All this time, the fetus is fed from the internal resource of the egg.

In the process of further development, the attachment site is transformed into the placenta. At this time, to prevent infection, a mucous plug is formed, which closes the entrance to the uterus. This whole process takes about two days.

If the embryo does not attach to the wall of the uterus, then a miscarriage occurs along with menstruation at the end of the cycle, and often the woman does not even know that she was pregnant.

In the next cycle, the egg is released from the follicle again, ovulation occurs, and the whole process is repeated again.

• What does a fertilized egg look like, structure:
• Villous membrane, chorion;
• Amnion (amniotic sac or membrane of water);

Embryo.

It is difficult to see exactly what the fertilized egg looks like even with the help of an ultrasound. Due to its small diameter, the embryo is difficult to detect inside the uterus if a woman is pregnant for less than a month.

It happens that even at a period of 6-7 weeks the embryo is not visible inside the egg - this may indicate a non-developing pregnancy. An empty ovum is quite rare and is often a symptom of genetic disorders in the woman or her partner.

Examination of the ovum

The diagnostic method used to study the life cycles of the fetal egg is called echography or, in other words, ultrasound diagnostics. It allows you to identify SVD, the average internal diameter of the ovum, and CTR, the coccygeal-parietal size of the fetus.

There is no need to worry that ultrasound will harm the fetus. Even in the early stages, radiation does not affect the health of the unborn child.

It is worth considering separately the 4th obstetric week of pregnancy, since it is during this period that nascent life can be seen using ultrasound. In the first days of the fourth week of pregnancy, the fertilized egg has a diameter of only 1 mm, and it is not possible to assess the details of fetal formation.

That is why an additional ultrasound is prescribed a few weeks after the first examination. However, after a couple of days, the size of the fertilized egg will increase to 3 mm, and it will be possible to see the yolk sac, with the help of which the embryo is nourished until the umbilical cord appears.

Towards the end of the fourth week, the diameter of the fertilized egg increases to 4 mm, during this period vital organs begin to develop: the heart, lungs, liver and pancreas.

On the last day of this period, the diameter of the ovum is 5 mm, and during an ultrasound it is already possible to detect an embryo whose size is only 1 mm. Literally in a day the egg grows up to 6 millimeters.

Formula for determining gestational age:

The average internal diameter of the ovum + 35 (if its size is less than 16 mm) or 30 (if the fetus is more than 16 mm). For example, diameter 17+30=47 weeks.

When studying the fertilized egg with echography, pathologies can be detected already in the early stages. The absence of an embryo inside the membrane, an “empty egg” or anembryony, may indicate an undeveloped pregnancy that will end in miscarriage or purging.

A picture that shows a discrepancy between the sizes of the growing embryo and egg in the absence of a heartbeat may indicate fetal fading, which also leads to miscarriage.

For example, if the embryo is much smaller than the membrane or the size of the bubbles is too small for the given period, then with a high degree of probability a miscarriage will occur at the end of the cycle.

The most common cause is chromosomal changes during conception, either congenital or caused by external influences.

For example, a woman, not knowing about pregnancy, takes pills, drinks alcohol or is exposed to other harmful influences, which leads to serious pathology in the development of the fetus and miscarriage.

Deformation of the ovum is not always a pathology, and in most cases is caused by increased uterine tone in the first period of pregnancy. Often the tone is accompanied by slight bleeding and pain in the lower third of the abdomen.

This problem can be solved with medication; pills are prescribed to reduce the number and intensity of contractions of the uterine muscles and hormonal pills to keep the fetus inside.

In case of detachment of the ovum in the case of a small affected area, hormonal treatment is carried out. For a woman during this period, bed rest in a hospital setting is required.