Second screening during pregnancy: timing. How many weeks do the second screening: terms, norms and interpretation of indicators during pregnancy Do the 2nd screening

At about 19-20 weeks of pregnancy, every future woman in labor is required to conduct a second screening (2 trimesters) and ultrasound. These dates were not chosen by chance: at this time it is most convenient to study hormones.

You already remember, was in the middle of the 1st trimester.

He usually shows that everything is fine.

Indeed, at that moment it is possible to determine with accuracy only the fetus is developing correctly or not. Understanding deviations from the norm at such a time is not easy.

But the results of screening can tell a lot.

So, what does the second examination show and what do they look at?

What it includes: basic analyzes

Screening is from the English "browsing". That is, the definition of a risk group in which the appearance of children with certain diseases is possible.

Probabilities can be calculated according to different principles. The most famous program is PRISCA (Prenatal RISk Assessment) - perinatal risk assessment.

The standard time for the second screening is from 16 to 20 weeks.

The later all the examinations are carried out, the more accurate the results will be. But it is also more dangerous to have an abortion.

Therefore, the optimal time for examination is 17-19 weeks.

Your doctor will refer you to:

• Biochemical screening of the 2nd trimester.
  • It's a triple test.
  • Here, blood will be taken from a vein and three components (AFP, hCG, estriol) of the blood will be checked for the presence of special markers.
  • Based on the analyzes, it will be clear what is the risk of diseases such as Down syndrome, Edwards.
  • The type of study is completely safe, because. there is no effect on the mother's body. It's just blood.

• . More accurate than usual.
  • It can be used to identify disorders such as heart disease, cleft lip or palate, diaphragmatic hernia, shortened bones, clubfoot, crossed fingers, and so on.
  • There may be minor anomalies that can be cured with time, drugs or surgery, and serious defects that will remain with the child for life.

• Cordocentesis.
  • Not a mandatory part of routine screening.
  • But if any abnormalities were detected during ultrasound or examination, the procedure is desirable.
  • Using a special needle, blood from the fetus will be taken from the umbilical cord in order to conduct more detailed examinations and obtain more accurate results.
  • The method is not completely secure. But according to statistics in 2% of cases after the procedure.
  • Often there are various hematomas and bleeding after the injection, which pass quite quickly.
  • In 1 case out of 100, an infection is introduced into the blood.

Often, PRISCA includes examinations such as the calculation of cervical transparency (calculated through ultrasound), the measurement of the coccygeal-parietal size, and many others.

Prognosis of possible diseases

Most often, perinatal screening of the 2nd trimester is carried out to find out if the child has certain diseases during pregnancy.

Down syndrome

The disease appears even at the moment of chromosome crossing immediately after conception.

Otherwise, the disease is called trisomy 21, i.e. The 21st pair of chromosomes is not a pair, but a trio.

This is due to the fact that in the sperm or in the egg at the time of conception there was one extra 21st chromosome. The probability is approximately 1-1.5%.

It is impossible to predict the appearance of the disease in a child. Does not depend on the woman and the father of the child. The age of the mother only slightly affects the likelihood of the syndrome.

neural tube defect

The neural tube is formed in the embryo around the 20th day of pregnancy in the form of a plate.

After a few more days, it should curl up into a tube.

These terms are not very long, so the process goes almost unnoticed.

The problem is this: it may not close completely or turn around in the future, which may cause defects in the spine.

Unfortunately, it is difficult to immediately determine the violation in the early stages.

By the middle of the 2nd trimester, namely by the time of the screening, the defect will be detected by ultrasound.

The result of the violation can be a cleft in the spine, a hernia and other neurological defects. The 2nd biochemical screening allows you to notice such troubles.

Edwards syndrome

The causes of the disease are similar to Down's syndrome.

This is where trisomy 18 occurs. Such children are born late, but outwardly similar to premature babies.

They are small, light, painful and weak.

Numerous defects in internal organs and parts of the body, which can also be seen on ultrasound. Such a child will not live long: a rare baby survives to his first birthday.

Fortunately, this syndrome is extremely rare: in 1 case out of 5000. But the probability still exists.

Screening results

The screening examination should take place on the same day.

A biochemical study of the 2nd trimester will show the level of three elements. What is the interpretation of the results?

A protein that is produced by the fetus itself, and not by the mother's body during pregnancy.

During the survey, its percentage is accurately calculated. It enters the woman's blood in certain quantities.

Any deviation from the norm means some kind of deviation in the development of the fetus.

According to PRISCA, levels should be around 15-95 U/mL at 15-19 weeks of gestation.

Results above the norm probably mean a violation in the development of the spinal cord, a defect in the neural tube.

If the ACE level is much below normal, Down syndrome, Edwards, Meckel, occipital hernia, liver necrosis, spina bifida are possible.

• Estriol

A hormone produced by the placenta. And starting from the second trimester, it is produced by the fetus itself.

At the same time, its level should constantly increase. At 17-18 weeks, the norm is 7-25. At 19-20 - 7.5-28.

If the level is lower than it should be, Down's syndrome, premature birth is possible.

human chorionic gonadotropin.

According to PRISCA, elevated levels are indicative of chromosomal abnormalities like Down syndrome and Edwards syndrome.

Tip: do not try to interpret the results of the examination or ultrasound on your own.

Without a medical education, there is a high probability of confusion - decoding is not so simple. And the doctor will describe everything clearly and in detail to you.

If the results of the second screening are not very good, do not rush to get upset: you will be assigned additional examinations, where the condition of the fetus will be determined with greater accuracy.

Is screening worth it?

Of course, this examination is not mandatory. Moreover, it is often paid.

And the results of the study are not always confirmed after the birth of the child.

Any examination prescribed by a doctor causes anxiety in most patients. This is especially true during pregnancy, when the expectant mother is no longer responsible for one, but for two lives. Of particular concern is the 2nd trimester screening. What is II screening? Why is the procedure needed? And how many indicators are studied? All this excites expectant mothers.

Why is this study needed, and what do they watch in the 2nd trimester?

How many mandatory prenatal screenings are considered normal? The Ministry of Health of the Russian Federation insists on conducting 3 standard screening studies for all pregnant women. They are mandatory for representatives of risk groups:

• the woman has reached the age of 35;
• consanguineous marriage;
• heredity (there are chromosomal pathologies in the family, a woman has children with genetic abnormalities);
• several self-abortions in an obstetric history;
• the threat of miscarriage;
• oncopathology of a pregnant woman, detected after 14 weeks of gestation;
• radiation exposure before conception or immediately after it of any of the partners;
• SARS in the period from 14 to 20 weeks;
• anomalies and diseases of the fetus, identified by the 1st screening.

If an oncological pathology is detected in a pregnant woman, she is referred for a consultation with a geneticist in order to resolve the issue of the need for additional biochemical research in the II trimester. Quite often, a repeated ultrasound scan in a perinatal center or a specialized clinic is sufficient.

Maternal and child organs evaluated during screening

What is included in the second screening? At this stage of the examination, both the main fetometric indicators and the functional state of the organs and systems of the fetus are looked at:

• fetal vertebral column and facial bones of the skull;
• condition of the genitourinary system;
• the structure of the myocardium;
• the level of development of the digestive organs;
• anatomy of brain structures;
• basic fetometric data (BPR, LZR, OB, OG, lengths of tubular bones).

With a certain position of the baby, the doctor can see the sexual characteristics of the child. In addition to the general assessment of the fetus, they also look at the state of the organs and systems of the mother's body, on which the life of the baby directly depends.

The doctor carefully examines:

• placenta (location and condition, that is, thickness, maturity and structure);
• amniotic fluid (their quantitative indicators);
• umbilical cord (number of vessels);
• uterus, its appendages and cervix.

According to the data of the II prenatal screening, the doctor makes reasonable conclusions about the presence / absence of anomalies in the development of the fetus, as well as violations of its condition, blood supply and a threat to the health and life of both the mother and her child.

Preparations for screening

How many stages in the 2nd survey? The plan of diagnostic measures for a pregnant woman at the second screening includes stage II, they are not complicated and do not take much time, but require little preparation. Stages of the 2nd screening:

1. a blood test for hormone levels (biochemistry) - currently performed according to indications.

Preparatory measures are not needed for ultrasound diagnostics. When performing the second screening, preparation is carried out for the sake of a biochemical test. You can’t eat before the analysis - he surrenders on an empty stomach. At least 4 hours should pass after eating. 30-40 minutes before the study, you can drink some water without gas, in the future it is better to refrain from taking liquids.

Screening time 2nd trimester

When is the best time to do the research? There is a strictly defined time range for this. The timing of the second screening during pregnancy is as follows:

• Biochemical screening in the 2nd trimester is done in the period of 16-20 weeks. This time is diagnostically significant, both for the effectiveness of the ultrasound diagnostic procedure, and for donating blood for biochemistry and determining the level of hormones. The optimal time is 18-19 weeks.
• The procedure for perinatal ultrasound screening of the 2nd trimester is best done a little later - after biochemistry - at 20-24 weeks.

At the same time, it is not at all necessary to do an ultrasound scan and donate blood for biochemistry on the same day. But it is not necessary to delay the analysis. If ultrasound can be repeated regardless of the gestation period, then biochemical analysis is informative in a strictly specified time range.

How are the examinations carried out?

Ultrasound in the II trimester follows the same rules as any other ultrasound examination during pregnancy. It has no absolute contraindications. The ultrasound procedure is painless, non-invasive and is considered one of the safest methods for examining a future mother and her baby. During the examination, the woman lies on her back in a comfortable position, the doctor lubricates the skin at the point of contact of the sensor with the skin with a hypoallergenic gel and performs diagnostics. The study is carried out through the anterior abdominal wall. The woman receives the results and interpretation of the data in her hands within a few minutes.

Blood for biochemistry is taken on an empty stomach. For the study, a small amount of venous blood is taken. Before the start of the study, it is necessary to provide personal data and data from ultrasound diagnostics. The obtained data is analyzed using special software. Results are ready within 14 days.

Results of biochemical screening

Data decryption is carried out by qualified personnel. He evaluates a number of indicators, each of which is compared with the norm. When deciphering a blood test, the level of the following hormones in the blood is assessed:

1. AFP (α-fetoprotein);
2. E3 (estriol);
3. HCG (human chorionic gonadotropin).

The norm of indicators of the second screening study directly depends on the period of pregnancy. For the II trimester, the norms are given in the table:

In some cases, the level of an inhibitor of FSH secretion (inhibin) is also evaluated. The evaluation of indicators of the II-nd screening is based on the average value (MoM). The average value is calculated using a special formula, taking into account the following data:

• body weight of a pregnant woman;
• age indicators;
• place of residence.

Average norms of hormone levels should be in the following range: from 0.5 MoM to 2.5 MoM. If the results are not within the specified range, the woman is referred for re-consultation by a geneticist. Biochemical data show the degree of risk of fetal diseases with genetic diseases, such as:

• Down syndrome;
• Patau syndrome;
• Edwards syndrome and others.

The norm is considered to be an indicator exceeding the risk of 1:380. A high degree of risk (1:250-1:360) requires a mandatory consultation with a geneticist. At extremely high degrees of risk (1:100), additional diagnostic measures are required. These are invasive measures, they carry a certain amount of danger to the mother and fetus, but they allow you to confirm the presence and type of anomaly by examining the baby's chromosome set.

Results of ultrasound diagnostics

Ultrasound of the second screening is a complex study. It allows you to assess the condition of the reproductive organs of a woman, the fetus and the structures that ensure its life and development. During an ultrasound examination, the doctor evaluates:

• facial bones of the skull, facial features, their size and location;
• development of the eyeballs;
• spinal column;
• the state of the lungs, the degree of their maturity;
• development of brain structures and heart;
• genitourinary and gastrointestinal systems;
• indicators of fetometry of the fetus;
• the presence of visually distinguishable genetic anomalies (number of limbs, fingers).

Thanks to ultrasound of the 2nd screening, the doctor has the opportunity, based on sufficiently reliable data, to judge the degree of development of the fetus, the gestational period, the presence / absence of defects in internal organs, and its viability.

Standards for screening indicators by week

The norms for some periods of gestation are shown in the table below. A period of 20 weeks is the last period when it is possible to determine and compare the levels of hormones in the blood. If for some reason a woman was not able to donate blood for biochemistry during this period, in the future this analysis loses its information content. Therefore, only the Doppler and CTG procedure is performed.

For a period of about 22 weeks, only ultrasound is performed, blood sampling for biochemistry is no longer performed. This is the final time period for making a decision about medical termination of pregnancy. Medical abortion is done up to 22 weeks, after 23 - termination of pregnancy is carried out by the method of artificial childbirth.

The table contains the following data:

• OG - head circumference,
• DP - length of the humerus,
• DPP - the length of the bones of the forearm,
• DB - length of the femur,
• OC - ​​abdominal circumference,
• DG - the length of the bones of the lower leg,
• fronto-occipital and biparietal dimensions,
• amniotic fluid index (AFI).

These are the main indicators that are informative regarding the development of the fetus, the presence or absence of structural abnormalities in it.

What can affect screening results?

If the data obtained during the examination correspond to the standards, the probability of having a healthy baby is very high. However, the percentage of error in this diagnosis still exists. And even not very good examination results do not always indicate a possible pathology.

That is, with poor performance, there is a chance that the baby will be born healthy, but even in a baby who was considered healthy throughout the entire gestation period, this or that pathology may be revealed after childbirth.

There are also a number of factors that affect the results of the examination, especially the biochemical test. These include:

• maternal chronic illness (eg, diabetes);
• bad habits (alcoholism, smoking, drug addiction);
• the weight of a pregnant woman (with excess weight, the indicators exceed the norm, with insufficient weight, they are underestimated);
• multiple pregnancy;
• pregnancy through IVF.

If a fetal pathology is detected that will lead to non-viability, severe deformities or developmental pathology, the woman is recommended to undergo additional, invasive examination methods (amniocentesis, cordocentesis), as well as an additional ultrasound procedure. In any case, the decision to maintain or terminate the pregnancy is made by the woman herself. The doctor can only give recommendations. Even if the pathology is confirmed by all studies with a high degree of certainty, a woman has the right to keep the pregnancy.

The course of the gestation period is subject to systematic monitoring. In the second trimester, the expectant mother is given another one. Based on the results, a conclusion is drawn up on the state of health of the woman and the child. In order to prevent intrauterine pathologies of the fetus, timely diagnosis is important. There is a need to study the optimal timing of screening.

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The essence of 2nd trimester screening

During the pregnancy period, an obstetrician-gynecologist may prescribe a 2nd trimester screening for a woman. It is then that the question arises of what it is and why it is carried out. Such research is intended identify pathologies in embryonic development. The level of possible complications is determined. Among the main goals of fetal screening at this stage are:

• determination of pathologies not detected during the diagnosis of the first trimester;
• clarification of the reliability of diagnoses made during the first stage of gestation;
• diagnosing the level of possible complications;
• detection of physiological disorders in the development of the embryo.

According to statistics, the first screening test is more accurate and reliable than the second procedure.

However, single results cannot be the basis for a definitive diagnosis. Upon completion of the second screening, the dynamics of fetal development indicators can be traced.

Due to this, trends are identified for the formation of conclusions.

It is important to remember that this event is not mandatory when carrying a fetus. It is prescribed only for those patients who are at risk.

Among the factors that serve as a reason for increased attention, it is customary to include:

• the age of the patient is over 35 years;
• early exposure of future parents;
• the presence of heredity with identified pathologies;
• detection of genetic pathologies in firstborns;
• the course of viral diseases during the first three months of gestation;
• the presence in the anamnesis of cases of spontaneous, abortive intervention and the birth of dead children;
• the occurrence of conception between blood relatives;
• susceptibility to harmful addictions (use of alcohol-containing and narcotic substances);
• the use of drugs that are unacceptable during gestation;
• identification of difficult working conditions.

If nothing threatens the condition of the pregnant woman, the event is not held. Be aware that this is a study woman can pass at will.

Information about what 2 pregnancy screening is, how many weeks it is carried out, is provided by the attending physician. The obstetrician-gynecologist during the consultation covers the main aspects of the procedure. Due to this, exciting moments are eliminated, which sometimes constitute a danger to the condition of the pregnant woman.

Perinatal screening of the 2nd trimester allows you to determine the following pathologies:

• abnormal development of the cardiovascular system;
• failure in the process of building the respiratory system;
• abnormal formation of the gastrointestinal tract;
• defect in the spinal cord and brain;
• pathological structure of the organs of the endocrine system;
• defective limb development.

In case of detection of phenomena that pose a danger to embryonic development, may be requested. The variant of resolving the situation depends on the results obtained, as well as the individual characteristics of the maternal organism.

Structure 2 screening

If there are indications, a woman is assigned to mandatory 2 screening during pregnancy.

What is included and what does the second screening show in the course of pregnancy - the main points of interest to patients.

As part of the second screening event, an ultrasound examination (ultrasound) of the body is carried out and a biochemical blood test is taken.

During the ultrasound examination, the following are subject to study:

• the structure and parameters of the fetal face (the eyes, nose, oral cleft, ears are identified; the development of the eyeball is examined; the size of the nose bone is determined);
• embryo parameters (represents a fetometric analysis);
• the level of embryonic development of the organs of the respiratory system;
• analysis of internal fetal organs for pathological structure(of interest are the brain and spinal cord, heart, gastrointestinal tract, urinary system);
• the number of fingers in a child on the upper and lower extremities;
• parameters of the fetal bladder (maturity level and thickness of the placenta);
• the state of the reproductive system in a pregnant woman (the area of ​​\u200b\u200bthe uterus, cervix, tubes and ovaries is analyzed);
• parameters of the amniotic fluid (the fact of leakage of amniotic fluid is established or refuted).

In addition to the above aspects, which shows ultrasound diagnostics, to be specified. This is achieved due to the greater severity of primary sexual characteristics.

Diagnosis implies a transabdominal principle. The sensor of the device is in contact with the skin in the abdomen. Before starting the procedure, a gel-like agent is applied.

Note! The data that ultrasound shows are supported by the results of a biochemical blood test. In the absence of violations according to the results of ultrasound markers, blood biochemistry does not give up.

Among the markers of fetal chromosomal pathology to be assessed during ultrasound, there are:

• slowdown or lack of embryonic development;
• oligohydramnios;
• ventriculomegaly;
• pyelectasis;
• discrepancy with the normative value of the size of the tubular bone;
• discrepancy between the parameters of the nasal bone;
• cyst in the vascular plexus of the brain.

Biochemical screening 2nd trimester

Biochemical screening of the 2nd trimester is blood test for the presence of specific compounds in it.

The concentration of these substances may vary depending on the identified violations.

The main goal for which biochemical screening of the 2nd trimester is carried out is to identify:

• failure in the formation of neural tubes in the brain and spinal cord;
• chromosomal anomalies (presented as Edwards syndrome and Down syndrome).

In the course of studying the composition of the blood, attention is focused on the level of:

• indicators of alpha-fetoprotein (AFP);
• human chorionic gonadotropin (hCG);
• free estriol;
• inhibina A.

A blood test gives an idea of ​​the dynamics of the condition. The diagnosis is made taking into account other research measures. Invasive measures, ultrasound diagnostic measures may be needed.

Experts are of the opinion that biochemical diagnostics is required for every pregnant woman. Even under the condition of a favorable course of pregnancy in the early stages, the expediency of conducting a study does not lose its relevance.

Screening preparation

Preparing for screening in the 2nd trimester does not require much effort. For ultrasound diagnostics, it is customary to highlight the following list of tips:

• The event can be held regardless of the time of day.
• The fullness of the bladder is not able to distort the results (by the second trimester, the volume of amniotic fluid increases; the level of amniotic fluid eliminates the need to fill the bladder).
• The fullness of the intestine does not play a role (by the time of the procedure, this organ is exposed to an enlarged uterus).

• Blood analysis must give up on an empty stomach(eating on the eve of the process may affect the accuracy of the results).
• The exclusive use of purified water is allowed.
• It is required to exclude the intake of fried foods, spicy dishes, flour products, sweets.
• Restriction of allergenic products (chocolates, citrus fruits, strawberries or other foods that cause an allergic reaction in a patient) is supposed.
• It is better to donate blood in the first half of the day (otherwise, a state of dizziness, nausea, vomiting may occur without the possibility of suppressing them with drugs).

The preparatory phase must be carried out with positive emotions and attitude. This is especially true when pathologies are detected after the first screening.

It should be remembered that the screening test is painless. Regardless of the patient's sensitivity threshold, there are no uncomfortable sensations. The procedure does not pose a danger to the health of the child being born.

When is the best time to do

Screening of the 2nd trimester is an exciting stage in the course of pregnancy.

The further bearing of the fetus depends on its results. That is why the question arises when it is better to do the procedure.

The optimal timing is stage from the 16th to the 20th week. Often, when asked when it is better to do this complex, experts recommend a 17-week period.

This feature is associated with sufficient development of the fetus. Its parameters allow you to detail individual areas of interest to assess its condition.

Note! The accuracy of the values ​​is directly dependent on such a category as the timing of the research. A correctly calculated period allows for the most reliable screening of the 2nd trimester. Otherwise, the obtained data cannot be used to clarify the diagnosis.

Useful video: second screening during pregnancy

Conclusion

Carrying out screening diagnostics facilitates the process of bearing a fetus. Knowing what a second pregnancy screening is, what specialists look at, frees a pregnant woman from unreasonable fears. Confidence in the condition of the fetus guarantees peace of mind for the expectant mother.

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Prenatal screening - This is a combined biochemical and ultrasound examination, consisting of a blood test to determine the level of the main hormones of pregnancy and a conventional fetal ultrasound with the measurement of several values.

First screening or "double test" (at 11-14 weeks)

Screening includes two stages: an ultrasound scan and blood sampling for analysis.

During an ultrasound examination, the diagnostician determines the number of fetuses, the gestational age and takes the size of the embryo: KTP, BDP, the size of the neck fold, nasal bone, and so on.

According to these data, we can say how well the baby develops in the womb.

Ultrasound screening and its norms

Assessment of the size of the embryo and its structure. Coccyx-parietal size (KTR)- this is one of the indicators of embryo development, the value of which corresponds to the gestational age.

KTP is the size from the tailbone to the crown, excluding the length of the legs.

There is a table of standard CTE values ​​​​according to the week of pregnancy (see table 1).

Table 1 - KTR norm according to gestational age

The deviation of the size of the fetus from the norm upwards indicates the rapid development of the baby, which is a harbinger of the bearing and birth of a large fetus.

Too small size of the fetal body indicates:

• initially incorrectly set gestational age by the district gynecologist, even before the visit to the diagnostician;
• developmental delay as a result of hormonal deficiency, infectious disease or other ailments in the mother of the child;
• genetic pathologies of fetal development;
• intrauterine death of the fetus (but only on condition that the fetal heartbeats are not heard).

Biparietal size (BDP) of the fetal head- This is an indicator of the development of the baby's brain, measured from temple to temple. This value also increases in proportion to the duration of pregnancy.

Table 2 - Norm of BPR of the fetal head at a certain gestational age

Exceeding the norm of BPR of the fetal head may indicate:

• a large fetus, if the other sizes are also above the norm for a week or two;
• spasmodic growth of the embryo, if the other dimensions are normal (in a week or two, all parameters should even out);
• the presence of a brain tumor or cerebral hernia (pathologies incompatible with life);
• hydrocephalus (dropsy) of the brain due to an infectious disease in a future mother (antibiotics are prescribed and, with successful treatment, the pregnancy persists).

The biparietal size is less than normal in case of underdevelopment of the brain or the absence of some of its sections.

The thickness of the collar space (TVP) or the size of the "neck crease"- this is the main indicator that, in case of deviation from the norm, indicates a chromosomal disease (Down syndrome, Edwards syndrome or another).

In a healthy child, TVP at the first screening should not be more than 3 mm (for ultrasound performed through the abdomen) and more than 2.5 mm (for vaginal ultrasound).

The value of TVP in itself does not mean anything, this is not a sentence, there is simply a risk. It is possible to talk about a high probability of developing chromosomal pathology in the fetus only in the case of poor results of a blood test for hormones and with a neck fold of more than 3 mm. Then, to clarify the diagnosis, a chorion biopsy is prescribed to confirm or refute the presence of a fetal chromosomal pathology.

Table 3 - Norms of TVP by weeks of pregnancy

The length of the nose bone. In a fetus with a chromosomal abnormality, ossification occurs later than in a healthy fetus, therefore, with deviations in development, the nasal bone at the first screening is either absent (at 11 weeks) or its value is too small (from 12 weeks).

The length of the nasal bone is compared with the standard value from the 12th week of pregnancy, at 10-11 weeks the doctor can only indicate its presence or absence.

If the length of the nasal bone does not correspond to the gestational age, but the rest of the indicators are normal, there is no reason for concern.
Most likely, this is an individual feature of the fetus, for example, the nose of such a baby will be small and snub-nosed, like that of parents or one of close relatives, for example, a grandmother or great-grandfather.

Table 4 - The norm of the length of the nasal bone

Also, at the first ultrasound screening, the diagnostician notes whether the bones of the cranial vault, butterfly, spine, limb bones, anterior abdominal wall, stomach, and bladder are visualized. At this time, these organs and parts of the body are already clearly visible.

Assessment of the vital activity of the fetus. In the first trimester of pregnancy, the vital activity of the embryo is characterized by cardiac and motor activity.

Since fetal movements are usually periodic and barely distinguishable at this time, only the embryonic heart rate has diagnostic value, and motor activity is simply noted as “determined”.

Heart rate (HR) fetus, regardless of gender, at 9-10 weeks should be in the range of 170-190 beats per minute, from 11 weeks until the end of pregnancy - 140-160 beats per minute.

Fetal heart rate below the norm (85-100 beats / min) or above the norm (more than 200 beats / min) is an alarming sign, in which an additional examination and, if necessary, treatment are prescribed.

Study of extraembryonic structures: yolk sac, chorion and amnion. Also, the ultrasound diagnostician in the protocol of screening ultrasound (in other words, in the form of ultrasound results) notes data on the yolk sac and chorion, on the appendages and walls of the uterus.

Yolk sac- this is the organ of the embryo, which until the 6th week is responsible for the production of vital proteins, plays the role of the primary liver, circulatory system, primary germ cells.

In general, the yolk sac performs various important functions up to the 12-13th week of pregnancy, then there is no need for it, because the fetus is already forming separate organs: the liver, spleen, etc., which will take on all the responsibilities for life support .

By the end of the first trimester, the yolk sac shrinks and turns into a cystic formation (yolk stalk), which is located near the base of the umbilical cord. Therefore, at 6-10 weeks, the yolk sac should be no more than 6 mm in diameter, and after 11-13 weeks, normally it is not visualized at all.

But everything is purely individual, the main thing is that he does not finish his functions ahead of schedule, so for 8-10 weeks it should be at least 2 mm (but not more than 6.0-7.0 mm) in diameter.

If up to 10 weeks the yolk sac is less than 2 mm, then this may indicate a non-developing pregnancy or a lack of progesterone (then Dufaston or Utrozhestan is prescribed), and if at any time in the first trimester the diameter of the yolk sac is more than 6-7 mm, then this indicates the risk of developing pathologies in the fetus.

Chorion- this is the outer shell of the embryo, covered with many villi that grow into the inner wall of the uterus. In the first trimester of pregnancy, the chorion provides:

• nutrition of the fetus with essential substances and oxygen;
• removal of carbon dioxide and other waste products;
• protection against the penetration of viruses and infections (although this function is not durable, but with timely treatment, the fetus does not become infected).

Within the normal range, the localization of the chorion is “at the bottom” of the uterine cavity (on the upper wall), on the anterior, posterior, or one of the side walls (left or right), and the structure of the chorion should not be changed.

The location of the chorion in the area of ​​\u200b\u200bthe internal pharynx (the transition of the uterus to the cervix), on the lower wall (at a distance of 2-3 cm from the pharynx) is called chorion presentation.

But such a diagnosis does not always indicate placenta previa in the future, usually the chorion “moves” and is thoroughly fixed higher.

Chorionic presentation increases the risk of spontaneous miscarriage, so with this diagnosis, stay in bed, move less and do not overwork. There is only one treatment: lie in bed for days (getting up only to use the toilet), sometimes raising your legs up and remaining in this position for 10-15 minutes.

By the end of the first trimester, the chorion will become the placenta, which will gradually "ripen" or, as they say, "age" until the end of pregnancy.

Until the 30th week of pregnancy - the degree of maturity is 0.

This evaluates the ability of the placenta to provide the child with everything necessary at each stage of pregnancy. There is also the concept of "premature aging of the placenta", which indicates a complication of the course of pregnancy.

Amnion- this is the inner water shell of the embryo, in which the amniotic fluid (amniotic fluid) accumulates.

The amount of amniotic fluid at 10 weeks is about 30 ml, at 12 weeks - 60 ml, and then it increases by 20-25 ml per week, and at 13-14 weeks there are already about 100 ml of water.

When examining the uterus with an uzist, an increased tone of the uterine myometrium (or uterine hypertonicity) can be detected. Normally, the uterus should not be in good shape.

Often in the results of ultrasound you can see the record "local thickening of the myometrium along the posterior / anterior wall", which means both a short-term change in the muscular layer of the uterus due to a feeling of excitement in a pregnant woman during an ultrasound scan, and an increased tone of the uterus, which is a threat of spontaneous miscarriage.

The cervix is ​​also examined, its pharynx should be closed. The length of the cervix at 10-14 weeks of pregnancy should be about 35-40 mm (but not less than 30 mm for nulliparous and 25 mm for multiparous). If it is shorter, then this indicates the risk of premature birth in the future. Approaching the day of the expected birth, the cervix will shorten (but should be at least 30 mm by the end of the pregnancy), and before the birth itself, her pharynx will open.

Deviation from the norm of some parameters during the first screening does not give cause for concern, just pregnancy in the future should be monitored more closely, and only after the second screening can we talk about the risk of developing malformations in the fetus.

Standard ultrasound protocol in the first trimester

Biochemical screening ("double test") and its interpretation

Biochemical screening of the first trimester involves the determination of two elements contained in a woman's blood: the level of free b-hCG and plasma protein-A - PAPP-A. These are the two hormones of pregnancy, and with the normal development of the baby, they should correspond to the norm.

Human chorionic gonadotropin (hCG) consists of two subunits - alpha and beta. Free beta-hCG is unique in its kind, therefore its value is taken as the main biochemical marker used to assess the risk of chromosomal pathology in the fetus.

Table 5 - The norm of b-hCG during pregnancy by week

An increase in the value of free b-hCG indicates:

• the risk of the fetus having Down syndrome (in case of exceeding the norm twice);
• multiple pregnancy (hCG level increases in proportion to the number of fetuses);
• the presence of diabetes in a pregnant woman;
• preeclampsia (i.e. with an increase in blood pressure + edema + detection of protein in the urine);
• malformations of the fetus;
• hydatidiform mole, choriocarcinoma (a rare type of tumor)

A decrease in the value of beta-hCG indicates:

• the risk of the fetus having Edwards syndrome (trisomy 18) or Patau syndrome (trisomy 13);
• threat of abortion;
• fetal growth retardation;
• chronic placental insufficiency.

PAPP-A Plasma pregnancy-associated protein A.

Table 6 - Norm of PAPP-A during pregnancy by week

The reduced content of PAPP-A in the blood of a pregnant woman gives good reason to assume that there is a risk:

• development of chromosomal pathology: Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), Patai syndrome (trisomy 13) or Cornelia de Lange syndrome;
• spontaneous miscarriage or intrauterine death of the fetus;
• placental insufficiency or fetal malnutrition (ie, insufficient body weight due to malnutrition of the baby);
• the development of preeclampsia (estimated together with the level of placental growth factor (PLGF). A high risk of developing preeclampsia is indicated by a decrease in PAPP-A together with a decrease in placental growth factor.

An increase in PAPP-A can be observed if:

• a woman is carrying twins/triplets;
• the fetus is large and the mass of the placenta is increased;
• the placenta is low.

For diagnostic purposes, both indicators are important, so they are usually considered in combination. So if PAPP-A is lowered and beta-hCG is increased, there is a risk of Down syndrome in the fetus, and if both indicators are reduced, Edwards syndrome or Patau syndrome (trisomy 13).

After 14 weeks of gestation, a PAPP-A test is considered non-informative.

Second screening of the II trimester (at 16-20 weeks)

II screening, as a rule, is prescribed for deviations in I screening, less often for the threat of abortion. In the absence of deviations, the second comprehensive screening can be omitted, and only a fetal ultrasound can be performed.

Ultrasound screening: norms and deviations

Screening ultrasound at this time is aimed at determining the "skeletal" structure of the fetus and the development of its internal organs.
Fetometry. The diagnostician notes the presentation of the fetus (breech or head) and takes other indicators of fetal development (see tables 7 and 8).

Table 7 - Normative dimensions of the fetus according to ultrasound

As with the first screening, the length of the nasal bone is also measured in the second. With other normal indicators, the deviation of the length of the nasal bone from the norm is not considered a sign of chromosomal pathologies in the fetus.

Table 8 - The norm of the length of the nasal bone

According to the measurements taken, it is possible to judge the true gestational age.

Fetal anatomy. An uzist examines the internal organs of the baby.

Table 9 - Normative values ​​of the fetal cerebellum by week

The dimensions of both the lateral ventricles of the brain and the large cistern of the fetus should not exceed 10-11 mm.

Usually, other indicators, such as: Nasolabial triangle, Eye sockets, Spine, 4-chamber section of the heart, Section through 3 vessels, Stomach, Intestine, Kidneys, Bladder, Lungs - in the absence of visible pathologies are marked as "normal".

The place of attachment of the umbilical cord to the anterior abdominal wall and to the center of the placenta is considered normal.

Abnormal attachment of the umbilical cord includes marginal, sheath and split, which leads to difficulties in the birth process, fetal hypoxia and even death during childbirth, if a planned CS is not prescribed or during premature birth.

Therefore, in order to avoid fetal death and blood loss in a woman during childbirth, a planned caesarean section (CS) is prescribed.

There is also a risk of developmental delay, but with normal baby development and careful monitoring of the woman in labor, everything will go well for both.

Placenta, umbilical cord, amniotic fluid. The placenta is most often located on the back wall of the uterus (in the form it can be specified more on the right or left), which is considered the most successful attachment, since this part of the uterus is best supplied with blood.

The area closer to the bottom also has a good blood supply.

But it happens that the placenta is localized on the anterior wall of the uterus, which is not considered something pathological, but this area is prone to stretching when the baby grows inside the mother's womb "plus" active movements of the crumbs - all this can lead to placental abruption. In addition, placenta previa is more common in women with an anterior placenta.

This is not critical, just this information is important for deciding on the method of delivery (whether a caesarean section is necessary and what difficulties may arise during childbirth).

Normally, the edge of the placenta should be 6-7 cm (or more) above the internal os. Its location in the lower part of the uterus in the region of the internal os is considered abnormal, partially or completely blocking it. This phenomenon is called "placenta previa" (or low placentation).

The thickness of the placenta is more informative to measure after the 20th week of pregnancy. Until this period, only its structure is noted: homogeneous or heterogeneous.

From 16 to 27-30 weeks of pregnancy, the structure of the placenta should be unchanged, homogeneous.

The structure with the expansion of the intervillous space (MVP), echo-negative formations and other kinds of abnormalities negatively affects the nutrition of the fetus, causing hypoxia and developmental delay. Therefore, treatment is prescribed with Curantil (normalizes blood circulation in the placenta), Actovegin (improves the supply of oxygen to the fetus). With timely treatment, babies are born healthy and on time.

After 30 weeks, there is a change in the placenta, its aging, and as a result, heterogeneity. In the later period, this is already a normal phenomenon that does not require additional examinations and treatment.

Normally, up to 30 weeks, the degree of maturity of the placenta is “zero”.

The amount of amniotic fluid. To determine their number, the diagnostician calculates the amniotic fluid index (AFI) according to measurements taken during ultrasound.

Table 10 - Norms of the amniotic fluid index by week

Find your week of pregnancy in the first column. The second column shows the normal range for a given period. If the IAI indicated by the uzist in the screening results is within this range, then the amount of amniotic fluid is normal, less than the norm means early oligohydramnios, and more means polyhydramnios.

There are two degrees of severity: moderate (minor) and severe (critical) oligohydramnios.

Severe oligohydramnios threatens with abnormal development of the fetal limbs, spinal deformity, and the baby's nervous system also suffers. As a rule, children who have suffered oligohydramnios in the womb are lagging behind in development and weight.

With severe oligohydramnios, drug treatment must be prescribed.

Moderate oligohydramnios usually does not require treatment, it is only necessary to improve nutrition, minimize physical activity, take a vitamin complex (it must include vitamin E).

In the absence of infections, preeclampsia and diabetes in the mother of the child, and with the development of the baby within the normal range, there is no reason for concern, most likely, this is a feature of the course of this pregnancy.

Normally, the umbilical cord has 3 vessels: 2 arteries and 1 vein. The absence of one artery can lead to various pathologies in the development of the fetus (heart disease, esophageal atresia and fistula, fetal hypoxia, disruption of the genitourinary or central nervous system).

But about the normal course of pregnancy, when the work of the missing artery is compensated by the existing one, we can talk about:

• normal results of blood tests for the content of hCG, free estriol and AFP, i.e. in the absence of chromosomal pathologies;
• good indicators of fetal development (according to ultrasound);
• the absence of defects in the structure of the fetal heart (if an open functional oval window is found in the fetus, you should not worry, it usually closes up to a year, but it is necessary to be observed by a cardiologist every 3-4 months);
• unimpaired blood flow in the placenta.

Babies with an anomaly such as the “single umbilical artery” (abbreviated as EAP) are usually born with a small weight, they can often get sick.

Up to a year, it is important to monitor changes in the child’s body, after a year of life, the crumbs are recommended to thoroughly take care of their health: organize a proper balanced diet, take vitamins and minerals, perform immunity-strengthening procedures - all this can put the state of a small organism in order.

Cervix and walls of the uterus. In the absence of deviations, the ultrasound protocol will indicate “The cervix and walls of the uterus without features” (or abbreviated b / o).

The length of the cervix in this trimester should be 40-45 mm, 35-40 mm is acceptable, but not less than 30 mm. If its opening and / or shortening is observed compared to the previous measurement during ultrasound or softening of its tissues, which is collectively called "isthmic-cervical insufficiency" (ICI), then the installation of an obstetric unloading pessary or suturing is prescribed to maintain the pregnancy and reach the prescribed term.

Visualization. Normally, it should be "satisfactory". Visualization is difficult when:

• the position of the fetus inconvenient for research (it’s just that the baby is positioned so that not everything can be seen and measured, or he was constantly spinning during the ultrasound);
• overweight (in the visualization column, the reason is indicated - due to subcutaneous adipose tissue (SAT));
• edema in the expectant mother
• hypertonicity of the uterus during ultrasound.

Standard ultrasound protocol in the second trimester

Biochemical screening or "triple test"

Biochemical blood screening of the second trimester is aimed at determining three indicators - the level of free b-hCG, free estriol and AFP.

The rate of free beta hCG look at the table below, and you will find the transcript, it is similar at each stage of pregnancy.

Table 11 - The rate of free b-hCG in the second trimester

Free estriol- This is one of the hormones of pregnancy, which reflects the functioning and development of the placenta. In the normal course of pregnancy, it progressively grows from the first days of the beginning of the formation of the placenta.

Table 12 - The rate of free estriol by week

An increase in the amount of free estriol in the blood of a pregnant woman is observed with multiple pregnancies or a large fetal weight.

A decrease in the level of estriol is noted with fetoplacental insufficiency, the threat of termination of pregnancy, cystic mole, intrauterine infection, adrenal hypoplasia or anencephaly (defect in the development of the neural tube) of the fetus, Down syndrome.

A decrease in free estriol by 40% or more of the standard value is considered critical.

Taking antibiotics during the test period can also affect the decrease in estriol in the woman's blood.

Alpha fetoprotein (AFP)- This is a protein produced in the liver and gastrointestinal tract of the baby, starting from the 5th week of pregnancy from conception.

This protein enters the mother's blood through the placenta and from the amniotic fluid, and begins to grow in it from the 10th week of pregnancy.

Table 13 - AFP norm by week of pregnancy

If during pregnancy a woman had a viral infection, and the baby had liver necrosis, then an increase in AFP in the blood serum of the pregnant woman is also observed.

Third screening (at 30-34 weeks)

In total, two screenings are carried out during pregnancy: in the first and second trimesters. In the third trimester of pregnancy, a kind of final monitoring of the health of the fetus is carried out, its position is monitored, the functionality of the placenta is assessed, and a decision is made on the method of delivery.

To do this, somewhere at 30-36 weeks, an ultrasound of the fetus is prescribed, and from 30-32 weeks, cardiotocography (abbreviated CTG - registration of changes in the fetal heart activity depending on its motor activity or uterine contractions).

Dopplerography can also be prescribed, which allows you to assess the strength of blood flow in the uterine, placental and main vessels of the fetus. With the help of this study, the doctor will find out if the baby has enough nutrients and oxygen, because it is better to prevent the occurrence of fetal hypoxia than to solve the health problems of the crumbs after childbirth.

It is the thickness of the placenta, along with the degree of maturity, that shows its ability to supply the fetus with everything necessary.

Table 14 - Thickness of the placenta (normal)

With a decrease in thickness, a diagnosis of placental hypoplasia is made. Usually this phenomenon causes late toxicosis, hypertension, atherosclerosis or infectious diseases suffered by a woman during pregnancy. In any case, treatment or maintenance therapy is prescribed.

Most often, placental hypoplasia is observed in fragile miniature women, because one of the factors in reducing the thickness of the placenta is the weight and physique of the pregnant woman. This is not scary, more dangerous is an increase in the thickness of the placenta and, as a result, its aging, which indicates a pathology that can lead to termination of pregnancy.

The thickness of the placenta increases with iron deficiency anemia, preeclampsia, diabetes mellitus, Rhesus conflict and with viral or infectious diseases (past or present) in a pregnant woman.

Normally, a gradual thickening of the placenta occurs in the third trimester, which is called its aging or maturity.

The degree of maturity of the placenta (normal):

• 0 degree - up to 27-30 weeks;
• 1 degree - 30-35 weeks;
• 2 degree - 35-39 weeks;
• Grade 3 - after 39 weeks.

Early aging of the placenta is fraught with a deficiency of nutrients and oxygen, which threatens with fetal hypoxia and developmental delay.

An important role in the third trimester is played by the amount of amniotic fluid. Below is a normative table for the amniotic fluid index - a parameter characterizing the amount of water.

Below is a table of standard fetal sizes by week of pregnancy. The baby may not meet the specified parameters a little, because all children are individual: someone will be large, someone will be small and fragile.

Table 16 - Normative dimensions of the fetus by ultrasound for the entire period of pregnancy

Preparing for a Screening Ultrasound

Transabdominal ultrasound - the sensor is driven along the abdominal wall of a woman, transvaginal ultrasound - the sensor is inserted into the vagina.

With a transabdominal ultrasound, a woman with a period of up to 12 weeks of pregnancy should come to the diagnosis with a full bladder, having drunk 1-1.5 liters of water half an hour or an hour before the visit to the ultrasound doctor. This is necessary so that the full bladder “squeezes out” the uterus from the pelvic cavity, which will make it possible to better examine it.

From the second trimester, the uterus increases in size and is well visualized without any preparation, so there is no need for a full bladder.

Take a handkerchief with you to wipe off the remaining special gel from your stomach.

With transvaginal ultrasound, it is first necessary to carry out hygiene of the external genital organs (without douching).

The doctor can tell you to buy a condom from the pharmacy in advance, which is put on the sensor for hygiene purposes, and go to the toilet to urinate if the last urination was more than an hour ago. To maintain intimate hygiene, take special wet wipes with you, which you can also purchase in advance at a pharmacy or in a store in the appropriate department.

Transvaginal ultrasound is usually performed only in the first trimester of pregnancy. With it, it is possible to detect a fetal egg in the uterine cavity even before the 5th week of pregnancy, abdominal ultrasound is not always possible at such an early stage.

The advantage of vaginal ultrasound is that it is able to determine ectopic pregnancy, the threat of miscarriage in the pathology of the location of the placenta, diseases of the ovaries, fallopian tubes, uterus and cervix. Also, a vaginal examination makes it possible to more accurately assess how the fetus develops, which can be difficult to do in overweight women (if there is a fold of fat on the abdomen).

For ultrasound examination, it is important that gases do not interfere with the examination, therefore, in case of flatulence (bloating), it is necessary to take 2 tablets of Espumizan after each meal the day before the ultrasound, and in the morning on the day of the examination, drink 2 tablets of Espumizan or a bag of Smecta, diluting it into the floor a glass of water.

Preparation for biochemical screening

Blood is taken from a vein, preferably in the morning and always on an empty stomach. The last meal should be 8-12 hours before sampling. In the morning on the day of blood sampling, you can only drink mineral water without gas. Remember that tea, juice and other similar liquids are also food.

The cost of comprehensive screening

If a planned ultrasound examination in city antenatal clinics is most often carried out for a small fee or completely free of charge, then prenatal screening is an expensive set of procedures.

Biochemical screening alone costs from 800 to 1600 rubles. (from 200 to 400 UAH) depending on the city and the “plus” laboratory, you also need to pay about 880-1060 rubles for a regular ultrasound of the fetus. (220-265 UAH). In total, comprehensive screening will cost at least 1,600 - 2,660 rubles. (420-665 UAH).

It makes no sense to conduct prenatal screening at any stage of pregnancy if you are not ready to have an abortion if doctors confirm that the fetus has mental retardation (Down syndrome, Edwards, etc.) or defects in any organs.

Comprehensive screening is designed for early diagnosis of pathologies in fetal development in order to be able to produce only healthy offspring.