If there are certain indications or at the request of a pregnant woman, at about the 16th week of the term, doctors can conduct a second screening - a simple but very informative procedure. About what are the prerequisites for the analysis and what parameters are studied with its help, we will tell in this article.

In 2000, Russian pregnant women began to be screened. This concept refers to a set of studies that allow you to identify the risks of developing genetic mutations in an unborn child. It is with the help of such a procedure that you can find out if the baby will have Down syndrome, Edwards syndrome, or anomalies in the development of the neural tube.

There are 2 screenings for pregnant women, both studies consist of ultrasound diagnostics, as well as a detailed biochemical blood test. The first time the procedure is carried out at 10-12 weeks of gestation, the second screening period falls on 16-20 weeks of pregnancy. In rare cases, and only if there are certain prerequisites, a third screening can be carried out for a pregnant woman.

Screening of the second trimester is not a mandatory procedure and can be carried out for a fee at the request of the woman or in the case when there are some indications. These indications include the following factors:

• blood relationship between the parents of the baby;
• the presence of genetic diseases in the family line;
• the age of the woman exceeding 35 years;
• previous pregnancies in children with developmental anomalies;
• miscarriages, frequent threats of miscarriage;
• an infectious disease transferred during the current pregnancy;
• taking medications that can adversely affect the health of the fetus;
• poor results of the first screening, during which a high risk of developing anomalies in the child was revealed;
• the presence of neoplasms in the body of a woman.

What parameters does the second screening examine?

During the second screening, ultrasound is often performed. Such diagnostics allows you to examine the fetus, placenta and internal organs of the mother. In the process of ultrasound diagnostics, the doctor pays attention to the following parameters:

• the size of the spine, head, abdomen and chest of the baby;
• proportionality of the limbs and other parts of the child's body;
• the state of the brain, the degree of development of the cerebellum and cerebral ventricles;
• the size and degree of development of the intestines, bladder, kidneys, liver, stomach;
• the state of large vessels and the heart;
• structure and basic features of the face.

Ultrasound during the second screening makes it possible to assess not only the child, but also the thickness, structure and degree of maturity of the amniotic sac, the amount of amniotic fluid, the position of the child in the womb, the presence or absence of anomalies in the cervix or uterine appendages.

In addition to ultrasound, during the second screening, blood is taken for biochemical analysis. It allows you to study 4 main indicators:

1. Alpha-fetoprotein, abbreviated as ACE. This substance is a protein in the blood serum of the fetus. ACE is produced by the body of the embryo from about 3 weeks after fertilization. The protein is responsible for the delivery of nutrients to the baby's blood, provides the child with protection from estrogens and too strong a reaction of the mother's immunity.
2. Human chorionic gonadotropin is the second indicator that must be examined in the process of a biochemical blood test when a second screening is done. HCG begins to be determined in the blood and urine of a pregnant woman in the first weeks after conception; almost all pregnancy tests respond to this hormone. Chorionic gonadotropin is first produced by the chorion, and then by the amniotic sac. HCG directly indicates the state of pregnancy, is involved in the production of the necessary hormones, and supports the normal course of the gestation process.
3. Free estriol is another hormone that must be examined during the second screening. After the appearance of human chorionic gonadotropin in the blood of a woman, the activity of estriol increases markedly. This hormone is produced mainly by the child's liver and amnion, and it is responsible for supplying the uterus and placenta with blood, the development of ducts in the mammary glands, and the functioning of the female reproductive system.
4. Sometimes during the screening process of the second trimester, an analysis is carried out for the content of inhibin A - a hormone, the level of which in a woman's blood rises sharply after fertilization. Inhibin is produced by the female ovaries, amnion and the child's body. As a rule, during screening, inhibin is analyzed extremely rarely and only in the case when the previous three parameters cannot form a clear picture.

Timing and features of the second screening

As mentioned earlier, second trimester screening consists of two main procedures: ultrasound and biochemical analysis of venous blood. Preparation for ultrasound diagnostics is not difficult. Ultrasound is performed transabdominally, that is, the sensor is applied to the outer surface of the abdomen. There is no need to drink a certain amount of fluid before the procedure, since the amniotic fluid already allows you to see a clear picture.

If you do not need to carry out any manipulations before starting an ultrasound diagnosis, then it is better to prepare in advance for a biochemical blood test. Preparation, first of all, includes the observance of a certain diet. Approximately 24 hours before the screening, you should exclude coffee, chocolate, cocoa, fatty foods, fried foods, exotic seafood and citrus fruits from your menu. At least 6 hours before the test, you should generally refuse food, since blood is taken on an empty stomach for such a case. No later than 4 hours before the procedure, you can drink some plain water.

The timing of the second screening during pregnancy ranges between 16 and 20 weeks. Initially held ultrasonography, and only then, taking into account its results, a blood test for hormones is carried out. The second screening is best done between 16 and 17 weeks.

Biochemical analysis indicators are processed by a special program and are handed out 2 weeks after blood sampling.

Second screening: normal indicators

When determining screening norms, the so-called MoM indicator is used. This parameter characterizes the degree of deviation of a particular indicator of the patient from the average value. Normally, MoM should fluctuate between 0.5-2.5 units. If the parameter is close to 1, this means that the hormone is closest to the average in the population. When MoM is above 1, it means that the indicator is above the average; when it is less than 1, it is below the average value in the population. When calculating the risks of manifestation of certain pathologies, MoM is adjusted depending on some factors: the mother's race, her weight, the presence of bad habits, etc.

If we determine the norms of the values ​​of biochemical parameters, then the screening of the second trimester should give the following results:

1. At the 16th week of pregnancy, the level of hCG in the blood should be from 10 to 58 thousand mU / ml. The level of alpha-fetoprotein at the same time should range from 15 to 95 U / ml. The level of estriol should be 5.4-21 nmol / l.
2. At 17 and 18 weeks, the indicators of chorionic gonadotropin will vary within 8057 thousand mU / ml. ACE at the same time will be 15-95 U / ml, and estriol - 6.6-25 nmol / l.
3. At the 19th week of the term, the hCG level should normally fluctuate within 7-49 thousand mU / ml, ACE will be the same as in previous cases, and estriol should be 7.5-28 nmol / l.
4. By the 20th week of pregnancy, chorionic gonadotropin will normally vary from 1.6 to 49 thousand mU / ml. The ACE level will be 27-125 U / ml, and the level of estriol, as at week 19, will be 7.5-28 nmol / l.

Now I would like to consider in more detail what anomalies deviations of screening indicators from the norm may indicate:

1. In the event that the content of chorionic gonadotropin in the blood exceeds the norm or is more than 2 MoM units, a child may be born with Down syndrome or Klinefelter syndrome. If hCG is below normal, the likelihood of Edwards syndrome in the baby increases.
2. Elevated levels of alpha-fetoprotein in the mother's blood may indicate abnormalities in the fetal nervous system, such as the presence of anencephaly or spina bifida. Often, an elevated ACE level is observed in women carrying more than 1 child. A decrease in this indicator also does not speak of anything good and may be evidence of the presence of Down syndrome or Edwards syndrome in the fetus.
3. Free estriol in the blood may deviate from the norm against the background of the use of certain medications. These drugs include some antibiotics, Prednisolone, Dexamethasone and other drugs. A pregnant woman who is being treated with any medication must indicate this information in her questionnaire filled out before the second screening. In the case when, even without taking drugs, the level of free estriol does not reach the norm, the baby in the womb with a certain degree of probability may have Down syndrome or Edwards syndrome. A reduced rate of estriol also sometimes indicates fetoplacental insufficiency, abnormalities in the development of the adrenal glands in the fetus, anencephaly, and the threat of miscarriage. An increase in the level of this hormone is often observed when carrying twins, in the case of a large child, as well as in liver diseases.
4. Inhibin A is elevated if the child has Down syndrome or some other chromosomal mutation. This indicator can be paid attention only in conjunction with other parameters, since there are often cases of an increase in the level of inhibin A against the background of normal indicators of other hormones. In such situations, children were most often born completely healthy.

Second screening during pregnancy. Video

The new word "screening" appears in the lexicon of a woman already in the first trimester of pregnancy. These are tests that show any hormonal fluctuations during pregnancy.

Screening is done to identify risk groups such as Down syndrome, neural tube malformations, and Edwards syndrome. The result can be found out after a blood test taken from a vein and ultrasound readings. The individual characteristics of the pregnant woman and the development of the unborn child are also taken into account. Everything is taken into account - height, weight, bad habits, the use of hormonal drugs.

Screening of the first trimester is a comprehensive examination for a period of 11 to 13 weeks of pregnancy. He must determine the risk of having a child with congenital malformations. Screening includes two tests - an examination and a blood test from a vein.

The first ultrasound determines the physique of the baby, the correct location of the legs and arms. The doctor examines the circulatory system of the fetus, the work of the heart, the length of the body relative to the norm. In addition, special measurements are made, such as measuring the thickness of the neck crease.

It should be borne in mind that the screening of the first trimester is called complex, so it is not worth drawing any conclusions based on only one indicator. If there are suspicions of genetic malformations, the woman is sent for additional research. First trimester screening is optional for all pregnant women. Moreover, in the antenatal clinic, they mostly don’t do such things and you have to donate blood in private clinics. However, those women who have an increased risk of pathologies are still sent for screening. These are those who give birth after the age of 35, who have patients in the family with genetic pathologies, expectant mothers who have had miscarriages or children with genetic abnormalities before.

In the first trimester of pregnancy, a blood test determines the content of b-hCG and PAPP-A, a plasma protein that is associated with pregnancy.

For (16-18 weeks), blood is already donated for three hormones - b-hCG, AFP and free estriol, sometimes, as an option, a fourth indicator is added - inhibin A.

Let's figure out a little what these hormones are, and how they can affect the outcome of pregnancy.

HCG is found in maternal serum. It is one of the main hormones during pregnancy. Screening determines . If it is lowered, then this indicates a pathology of the placenta. The increased content of the hormone most often occurs due to chromosomal abnormalities in the fetus or indicates that you are carrying two or more babies.

The PAPP-A test is a determination in the blood of the produced protein A. Screening also determines the level of this protein. If it is significantly underestimated, then this indicates some chromosomal abnormalities, which in turn can lead to the fact that the baby may develop Down syndrome or Edwards syndrome.

The level of estriol, a female steroid sex hormone, in maternal blood is measured by screening in the second trimester of pregnancy. Estriol is produced by the placenta during pregnancy. And if it is not produced enough, then this indicates possible violations in the development of the fetus.

Alpha-fetoprotein (AFP) is found in maternal serum. This is also a specific protein that is produced only during pregnancy. If the normal state of the fetus is disturbed, then this also affects the results - it decreases or increases in the blood. An increase indicates the development of congenital malformations and diseases, a decrease indicates Down's syndrome. A sharp increase in the amount of AFP can lead to fetal death.

With the results of the screening in hand, do not panic if one of the results is not normal. It is important to understand that doctors draw conclusions based on general conclusions, a comprehensive assessment. In addition, even if there is a high risk of malformations in the fetus, then you need to go for a consultation with a geneticist.

It should be noted that screening only indicates the possibility that there is a problem, in addition, deviations from the norm can be due to various reasons - taking hormonal drugs during pregnancy or untimely delivery of tests.

Especially for- Maryana Surma

From a guest

Girls, I am writing a review in the hope that someone will need my experience. First pregnancy, 33 years old. Pregnancy is very long-awaited. Seeing 2 strips fortunately knew no bounds. All happy moments are over after 1 screening. The ultrasound is excellent, the collar space is normal. I hand over the analysis of a blood - result 1:84. The doctor suggests not to worry and pass the screening of the 2nd trimester (a huge mistake! I spent time and did not get the final result). The result of the second screening: excellent ultrasound and blood risk of 1:40. Then I do a DNA test, the result from Hong Kong is not comforting. The probability of Down syndrome is 1:20, 99%. But even less the result of the DNA test is not a diagnosis and does not serve as a basis for termination of pregnancy, and the term is already 19 weeks. Further, the geneticist insists on amniocentesis, arguing that the result may be different. I am waiting for the amnio result for 3 weeks. During this time, I again go to the ultrasound. The results are perfect! Nose, limbs, brain, bones, etc. - Everything is okay! I pray 24 hours a day for health, cry, wait, hope. Then I go for the result of the amniocentesis and get a sentence - a child with Down's syndrome! Naturally, I make a decision to take a break, because I myself worked in a rehabilitation center with such children and I know that the severity of potalogues is not predictable! From a mild form to an immovable log with a bunch of additional complications on the heart and other organs. Now I'm in the hospital and waiting for tomorrow's artificial birth. Girls, summing up, I want to say that if you do not plan to give birth with any diagnosis, do not waste time on unnecessary diagnostics. Ultrasound will not show everything, even with the latest equipment and an experienced doctor. The second screening definitely took 3 weeks from me in vain. Now I lie and sob, and the term is already 23 weeks!

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 ultrasound of the fetus 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 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 earlier due date, therefore, at 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 premature aging 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 a risk premature birth in 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(the level of hCG increases in proportion to the number of fetuses);
• the presence of diabetes in a pregnant woman;
• gestosis (i.e. with an increase 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 (assessed 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 its development. 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 in case of premature birth.

Therefore, in order to avoid the death of the fetus and blood loss in a woman during childbirth, a planned C-section(CS).

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 on the 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. On the late term 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 this 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, suffers and nervous system baby. 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 establish nutrition, minimize physical activity, take vitamin complex(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 his health: organize a proper balanced diet, take vitamins and minerals, perform immunity-strengthening procedures - all this can bring 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 save 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 abortion, hydatidiform mole, intrauterine infection, adrenal hypoplasia or anencephaly (neural tube defect) 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 as 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(transferred 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 transabdominal ultrasound, a woman with a period of up to 12 weeks of pregnancy should come for diagnosis with a complete bladder by drinking 1-1.5 liters of water half an hour to an hour before a visit to an uzist. 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. For supporting intimate hygiene bring special wet wipes, which are also purchased 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, spreading it to 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 routine 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.

16 weeks from the moment of conception refers to the second trimester of pregnancy and corresponds to 18 obstetric week. Ultrasound diagnostics allows you to track the formation of the fetus, comparing the data with the norm.

The main purpose of the procedure is the detection of pathologies caused by chromosomal abnormalities, severe defects. At this stage, the main organs and systems of the fetus reach sufficient sizes to detect violations. The size of the baby allows for a thorough examination and assessment of development.

At a period of 14 - 16 weeks, pregnant women are prescribed a planned study of hormonal status (PAPP-A, hCG, estriol, ACE). The procedure is aimed at detecting fetal abnormalities. If the examination revealed a hormonal imbalance, the doctor prescribes an ultrasound scan to the patient at the 16th week of pregnancy.

The procedure is prescribed by a doctor in a number of cases:

1. Poor results on the first screening test.
2. Negative hormone levels.
3. Suspicion of missed pregnancy.
4. Multiple pregnancy.
5. Complaints of a woman in pain.
6. Miscarriage, fetal defects in a previous pregnancy.
7. The presence of children born with genome pathology.
8. Pathologies of the development of the placenta, polyhydramnios or oligohydramnios in history.

Symptoms such as uterine tone, spotting are a reason for urgent hospitalization.

Important! A late diagnosis of a missed pregnancy can lead to serious consequences.

If the research data indicate a high probability of fetal malformations, the patient receives a referral for the study of amniotic fluid - amniocentesis.

Mother's condition and fetal development

Week 16 is marked by the first movements of the baby in the womb. primiparous, plump women usually feel fetal movements at a later date.

The tissues of the body accumulate fluid and sodium salts, which leads to swelling of the extremities. The kidneys of the expectant mother work with increased stress. The rapid growth of the uterus makes all systems and the most important organs work in an enhanced mode. There are pains in the lumbar region.

A baby at 16 weeks of pregnancy from conception demonstrates excellent abilities:

• movement in the amniotic fluid;
• swallowing amniotic fluid with respiratory movements.

The child has periods of sleep and wakefulness. The limbs of the baby have formed, the hands touch the tiny face, clenched into fists. The mother's emotions are transferred to the child, who may already be experiencing anxiety.

What are they watching?

A woman can receive a protocol and a photo of the ultrasound results at 16.17 weeks of pregnancy. Based on the data, the doctor forms a biophysical profile of the fetus.

Important! The presence of genetic abnormalities requires a woman to make a decision to terminate the pregnancy for medical reasons.

A sufficient size makes it possible to diagnose malformations of the child with a high probability, such as:

• syndromes associated with genome disorders (Down, Edwards, other chromosomal abnormalities);
• malformations of the heart, brain;
• assessment of the size of tubular bones (shoulder, femur), nasal bone;
• fruit size;
• the amount of amniotic fluid;
• localization of the placenta.

Proper intrauterine nutrition of the fetus depends on the state of the placenta.

Incorrect location of the organ (full presentation) requires prompt resolution of childbirth, restriction of motor activity and sexual activity.

An ultrasound specialist assesses the condition of the cervix, which should normally be closed.

Photo of the fetus: is it possible to determine the sex of the child?

There is a real opportunity to determine the sex of the baby on ultrasound. At week 16, the information is conjectural.

The fetus moves freely in the amniotic fluid. Fingers have formed on tiny arms and legs, which mom can see on the ultrasound photo. The child demonstrates magnificent facial expressions, reflexively grimacing and smiling. A yawning baby is a beautiful moment that a photograph can capture.

The genitals are not yet sufficiently developed, the boy's testicles are in the scrotum. The fallopian tubes, the uterus of the girl have already formed. With an unsuccessful location, the child can block the examination area with a leg or handle, which makes it difficult to determine the sex.

A specialized center equipped with high-precision equipment will most likely tell the mother who is preparing for the birth.

Photo of a boy

Photo girls

Research Norms: Fetal Size

Normal for 16 weeks pregnant prenatal development the size of the fetus is considered to be from 14 to 20 cm with a weight of 140 to 230 g.

Diagnostics is performed in accordance with the established protocol and takes into account all the necessary parameters:

1. The number of fruits.
2. The cervix is ​​at least 30 mm.
3. BDP (distance between the parietal tubercles) - 37 - 47 mm.
4. LZR (OFD, fronto-occipital size) - from 49 to 60 mm.
5. Exhaust gas (HC, head circumference) - 131 - 161 mm.
6. DP (HUM length of the humerus) - from 15 to 20 mm.
7. Coolant (AC, abdominal circumference) - about 122 mm.
8. DG (diameter of the chest) - about 41 mm.
9. Length femur(FML) - from 23 to 31 mm.
10. The size of the humerus is from 15 to 21 mm.
11. The bone of the forearm is from 17 to 23 mm.
12. Leg length - 23 - 31 mm.
13. The systolic-diastolic ratio in the umbilical artery (SDO) is from 4.55 to 4.67.
14. Heart rate (HR) - from 140 to 160 beats per minute.

The protocol records the condition, the degree of maturity of the placenta, the status of the cervix and pharynx, the tone of the uterus. The placenta at 16 weeks has zero maturity. Areas of infarction, calcifications should be absent. The specialist determines the compliance with the norm of amniotic fluid.

3D - ultrasound at 16 weeks: is screening carried out?

Modern ultrasound scanners with advanced capabilities provide a picture of the fetus in 3-D format, which allows the specialist and parents to observe a three-dimensional image of the baby. The procedure does not require special preparation and lasts up to 60 minutes. The method differs in data accuracy.

3D photo of the fetus

In the absence of abnormalities, a routine ultrasound examination is carried out between 18 and 22 weeks of embryonic development. In case of poor results of the first study, with an unfavorable hormonal status, the doctor recommends screening at 16 weeks.

The appointment is caused by the need to make a decision to terminate the pregnancy for medical reasons, or to preserve the fetus. The new data often refutes the fears raised by the results of the first screening.

How do they do it, do they need preparation?

At the 16th week of embryonic development, ultrasound is performed transabdominally. A sufficient amount of amniotic fluid eliminates the need to fill the bladder.

The belly is covered with a gel, the smooth transducer glides easily over the surface of the skin. The procedure does not require prior preparation.

Uncomfortable position of the fetus may necessitate a change in position. The woman will be asked to stand up and move around a little.

With the stubborn unwillingness of the fetus to change the position, the study can be rescheduled for another day. Placental diagnosis is performed vaginally to accurately determine the distance between the placenta and the cervix.

Where is the test done and how much does it cost?

The free procedure is carried out in the antenatal clinic as prescribed by the local doctor. To obtain accurate results, you can use the services of a specialized center staffed by qualified personnel and high-resolution equipment.

Centers for gynecology and obstetrics offer examinations costing from 1,000 to 1,500 rubles. The service includes dopplerometry, 3-D or 4-D examination with video recording on disk media. The usual two-dimensional ultrasound - the procedure costs from 600 to 800 rubles. A screening test to determine the hormonal status and substantiate the risk of defects will cost from 2,500 to 3,600 rubles.

Conclusion

Prenatal ultrasound at week 16 allows you to diagnose fetal anomalies with high certainty. Ultrasound examination is a safe, informative way to determine the well-being of the child and mother. Ultrasound of the 16th week of pregnancy answers all the questions of the first screening and hormonal testing. The event allows the doctor to timely adjust the tactics of pregnancy.

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.

The second screening during pregnancy also includes an ultrasound examination and a biochemical analysis. A woman may refuse prenatal screening, but doctors do not recommend neglecting the possibilities of modern diagnostics. In some cases, additional research becomes mandatory.

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.

A blood test as part of screening is done on an empty stomach so that the results are as informative as possible. Based on the data obtained, the doctor identifies the compliance of the development of the fetus with the standards, and also checks the threat of genetic abnormalities

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 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:

Deadline (weeks)	EZ (nmol/l)	hCG (mU / ml)	AFP (u/ml)
16	5,4-21	10-58	15-95
17	6,6-25	8-57	15-95
18	6,6-25	8-57	15-95
19	7,5-28	7-49	15-95
20	7,5-28	1,6-49	27-125

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.

HCG (chorionic gonadotropin) is the main “pregnancy hormone” that appears in a woman’s body. It is he who is a key component of determining pregnancy using a test. In the process of developing the unborn baby, the number hCG hormone is constantly increasing, it has its own norms at each gestation period

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, 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 failed 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.

If a woman has not passed a biochemical blood test for up to 20 weeks of pregnancy, it is no longer relevant. To determine the condition of the fetus, dopplerometry is prescribed, which clearly demonstrates the supply of blood to the baby's organs and systems, and also allows you to see the blood flow in the uterus, placenta and umbilical cord

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.

Indicator	16 weeks	20 weeks	22 weeks
OG	112-136 mm	154-186 mm	178-212 mm
DP	15-21 mm	26-34mm	31-39 mm
DPP	12-18 mm	22-29 mm	26-34mm
DB	17-23 mm	29-37 mm	35-43mm
coolant	88-116 mm	124-164 mm	148-190 mm
DG	15-21 mm	26-34mm	31-39 mm
LZR	41-49 mm	56-68 mm
BDP	31-37mm	43-53 mm	48-60 mm
IAH	73-201 mm	85-230 mm	89-235 mm
Maturity of the placenta		0
Placenta thickness		16.7-28.6mm

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.