2 screening ultrasound results. Biochemical laboratory research. Screening preparation

In the second trimester, a pregnant woman is assigned a second screening, confirming or refuting the data obtained in the first comprehensive study. This period is the most suitable for diagnosing the hormonal level of the fetus. The data obtained make it possible to assess its development. This article details what are the screening norms for the 2nd trimester by ultrasound, blood test.

What is the purpose of the second examination?

The second screening examination is carried out around 16-20 weeks of pregnancy. These timings are not random. Since the fetus has grown up, it has already laid all the main systems important for life support. The study conducted up to 12 weeks refers to the first screening. Diagnostics has a specific goal of identifying anomalies of systems, their organs, detecting chromosomal disorders. If there are serious abnormalities, doctors may recommend premature birth.

Who is at risk

The second screening is assigned to every woman in an interesting position. However, the risk group for this study consists of the following pregnant women:

• primiparas who are over 35 years old;
• people who are closely related;
• women with burdened gynecological history;
• women working in hazardous working conditions;
• with burdened heredity;
• in the presence of a history of stillborn children, miscarriages, missed pregnancy;
• pregnant women taking alcohol, drugs.

Second trimester screening is a comprehensive study that includes ultrasound diagnostics and a biochemical test. If a woman easily tolerates pregnancy, the baby develops in accordance with the norm, then, in this situation, the doctor does not prescribe a second test.

ultrasound diagnostics

At the second screening, a second ultrasound is prescribed. During which the doctor receives information about how many fetuses women have, that is, whether the pregnancy is multiple, the gestational age is specified. Sometimes it differs from what determined the first result. The doctor also informs about the expected date of birth and, if the woman wishes, can tell the sex of the child.

The second ultrasound during pregnancy evaluates indicators such as:

• anatomy of internal systems;
• what is the heart rate of the fetus;
• the weight of the baby and its comparison according to a special formula with the previous result;
• what is the state of the amniotic fluid.

The doctor pays the most attention to such parameters as:

• face structure;
• fruit size;
• what maturity have the baby's lungs;
• organ structure;
• the number of fingers;
• formation of the placenta;
• amniotic fluid volume.

As a result, the doctor writes out a conclusion about the condition of the fetus, the presence of developmental disorders in it. If abnormalities are detected by ultrasound, then the woman is recommended to undergo a Doppler study. This diagnosis will assess the patency of blood vessels, uterine, placental, arterial blood flow. As well as the degree of oxygen saturation of the baby's brain in a given period of time.

Fetal size results by month

Important! To get the most accurate diagnosis, the 2nd trimester ultrasound should be done twice with Doppler, with a gap of two weeks. Moreover, it is desirable to pass the examination on two different devices.

The results of ultrasound diagnostics

When the second ultrasound examination results in a poor result of the development of the baby, then the woman is assigned a diagnosis with a Doppler. It is carried out at any time and does not require additional preparation. The received data is recorded on the tape. This will allow further monitoring of treatment and note the presence of changes. Deciphering ultrasound 2 screening evaluates:

• vessels of the uterus;
• umbilical arteries;
• vessels of the child's brain.

When determining the state of the vessels of the uterus, the resistance index is used. The doctor evaluates separately the left, right uterine artery. This is due to the fact that in the presence of toxicosis, there is a violation of the blood circulation of one vessel. If you analyze the results of only one artery, you will get incorrect, false information that can harm the expectant mother and fetus.

For your information, if a woman suffers from toxicosis in the third trimester, then she has impaired blood flow in the right uterine vessel. With late toxicosis, negative consequences for the fetus may follow. The standards for the 20th week of the resistance index are 0.52. Moreover, the permissible limit can vary from 0.37 to 0.70. It is necessary to examine the umbilical cord when the fetus is at rest.

And also with his heart rate, ranging from 120 to 160 beats per minute. This is due to the fact that with any deviations in the heart rate, there is a change in the resistance index in the umbilical artery. The umbilical cord contains two main arteries, one vein. Ultrasound of the second screening aims to detect the presence of an anomaly.

If the blood vessels have some deviations, then the baby suffers from a nutritional deficiency. This will negatively affect further growth and development. There are times when the fetus adjusts to the situation that has been created. As a result, a healthy baby with a low weight is born.

During the diagnosis, it is possible to assess the possibility of developing fetal anomalies

When only one blood vessel with impaired blood flow functions, then there is a possibility of a negative outcome of pregnancy. The woman will need to undergo an additional ultrasound and donate blood for the presence of chromosomal abnormalities. If the blood flow of the arteries of the head is disturbed, a reduced pulsation index will be observed. Its elevated level suggests the presence of cerebral hemorrhage. The norm of PI is 1.83. Its allowable parameter varies from 1.36 to 2.31.

Blood test

After the ultrasound results are obtained, the woman is assigned a blood test for biochemistry, the so-called triple test, which will detect the following substances in the blood:

• HCG hormone, which is observed only during pregnancy. It helps to determine whether conception has occurred in home diagnostics.
• AFP protein. The presence of normal indicators indicates the provision of the baby with the necessary immunity from the mother.
• The hormone of the steroid type NE promotes the natural exchange between maternal and child substances.

Result

After receiving the results of a blood test, the doctor compares his indicators with the norm. In this case, it is necessary to take into account the moment in which the study took place. Based on the data obtained, an assumption is made about how the pregnancy proceeds, what is the state of health of the baby.

HCG norms

A good result can be expected at the following rates (measurements are given in ng / ml):

• 10,000 to 58,000 at 16 weeks pregnant
• 8000 to 57000 between 17-18 weeks;
• from 7000 to 49000 at 19 weeks of pregnancy.

If a woman has a slight deviation of the second screening during the study, then do not despair, because it does not carry much value. When the level is higher than expected, then this fact may indicate pregnancy with more than one fetus. If the rate rises by half, then there is a risk of having a child with Down syndrome. For your information, it is pointless to conduct screening tests with multiple pregnancies, since its results will be slightly overestimated.

In addition to multiple pregnancies, the cause of an increased hCG result may suggest diabetes in a woman or fetal chromosomal abnormalities. An underestimated result of the hormone indicates the possibility of pregnancy fading, the development of chromosomal abnormalities. In addition, a decrease in the rate may be a sign of an existing threat of miscarriage, a failed placenta, and the presence of Patau's syndrome.

Norms of AFP, hCG by weeks, which are guided by when deciphering the results of the analysis

AFP guidelines

The AFP protein is produced by the fetal body after 5 weeks of intrauterine development. With the help of amniotic fluid, the protein enters the circulatory system of the mother. The AFP parameters include the following norms, measured in units / ml:

• 15-60 between 12-14 weeks;
• 15–95 between 15–19 weeks;
• 27-125 at 20 weeks.

If during the study a reduced amount of protein was found in the baby's liver, then this is a reason to suspect the presence of Down syndrome. In addition, this result may indicate an incorrectly determined gestational age, cystic drift of the fetus. When an elevated level of AFP is detected during the examination, it can be assumed that the nervous system is developing abnormally, a liver disorder.

Usually these pathologies are caused by a viral infection, which a woman has in the first trimester of pregnancy.

NO norms

The NE steroid hormone has the following normal values, measured in ng / ml:

• 5.7 to 15 between 13-14 weeks;
• 5.4 to 21 between 15-16 weeks;
• 6.6 to 25 between 17-18 weeks;
• 7.5 to 28 between 19-20 weeks.

When screening detects a deviation in the form of an increase in the norm, this may be a sign of a multiple pregnancy. In addition, an increase in NE indicates impaired liver function, a large fetus. A reduced rate is formed as a result of infection of the baby, early use of antibiotics, developmental anomalies, insufficiency of the placental type.

A critical decrease in the NE hormone is a sign of:

• threats of miscarriage;
• anomalies of the adrenal glands;
• placental disorders;
• Down syndrome.

In addition, the NE indicator may be overestimated if the woman was taking antibiotics at the time of the test.

At the second screening, the fetal blood supply is assessed

Important! The deviation of NE should not be considered as direct evidence of pathologies. If the results are poor, additional testing should be performed.

Factors affecting the study

There are a number of relationships that affect how screening results are obtained. This diagnosis is inherent in a small percentage of error. Even flawless analyzes may not always tell about the presence of pathology. Accordingly, with poor results, a healthy baby can be born. This applies to a biochemical blood test.

Factors influencing research include:

• the presence of chronic diseases of the mother, for example, diseased kidneys, liver;
• the presence of bad habits, such as: smoking, alcohol abuse;
• overweight, which increases performance;
• multiple pregnancy;
• conception as a result of IVF.

What to do if a woman has bad screening test results

If a woman has poor results, you should not panic. More often than not, 10% of them are wrong. However, with a high degree of risk, the expectant mother needs to contact a geneticist as soon as possible, who will prescribe additional tests to assess the presence of a congenital or chromosomal pathology. The most commonly recommended test is:

• Cordocentosis is the collection of fetal blood through the umbilical cord. This test is prescribed no earlier than 18 weeks. It often causes miscarriage, intrauterine infection of the baby.
• Amniocentesis is the assessment of amniotic fluid. To collect them, the doctor pierces the peritoneum. This analysis is quite effective, but often leads to miscarriage.
• NIPT can be done from 10 weeks. Testing is done by drawing the mother's blood from a vein. If a negative result is obtained, then this is a 100% guarantee of the birth of a healthy child.

A separate deviation should not be considered as an indicator of a pathological phenomenon. It is possible to judge anomalies only after a comprehensive study.

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 determines 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 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:

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 development of the future baby, the amount of the 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 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.

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	17-23mm	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	31-37 mm	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.

With the onset of pregnancy, every woman periodically visits a doctor, takes laboratory tests, undergoes an ultrasound examination (screening of the 2nd trimester), which allow assessing the condition of the fetus, identifying the slightest changes or developmental pathologies. Throughout pregnancy, a woman should undergo three routine examinations. If a pathology is suspected, the woman has a history of chronic diseases, the number of ultrasound procedures can be increased. It has been proven that ultrasound is a safe and informative research method that does not harm the fetus and does not affect the course of pregnancy. The doctor without fail prescribes screening, which provides a set of studies, including ultrasound diagnostics and laboratory blood and urine tests. The diagnostic results help the doctor to determine the norms and possible complications, to recognize anomalies or congenital pathologies.

The second screening of pregnant women is carried out in the second trimester of gestational age. It is mandatory, held at 16 - 19 weeks. The main indicators that the doctor pays attention to are (human chorionic gonadotropin), AFP (alpha-fetoprotein) and free estriol (E3), as well as ultrasound results. If a pathology is suspected, a screening test may be prescribed to assess the hormonal background. Screening of the 2nd trimester should not frighten a pregnant woman, since it is a mandatory research method. If the pregnancy proceeds without complications, it is not necessary to undergo a complete diagnosis, you can do with an ultrasound diagnosis. In order to get acquainted with the screening in more detail, it is important to know when it is prescribed, what its norms and deviations are, as well as how to properly prepare for the procedure in order to get the highest possible results.

Should pregnant women undergo a second screening?

The main purpose of screening in the second trimester is to identify malformations in the development of the fetus and establish possible risks for the expectant mother. This research method is assigned to confirm or refute the various risks that were obtained during the initial diagnosis in the first trimester. Full screening is not assigned to all women, but only to those who are at risk, suffer from chronic pathologies or have a hard time bearing a child. The main indications for diagnosis are the following conditions and diseases:

• woman's age after 35 years;
• bad heredity;
• genetic diseases;
• viral diseases in the first trimester;
• miscarriages, fetal fading, in the past;
• conception of a child by close relatives;
• dependence of parents on drugs, alcohol;
• taking medications that are prohibited during pregnancy;
• autoimmune diseases;
• chronic diseases of internal organs and systems that can harm the fetus, affect its growth and development.

Other diseases or conditions that can lead to the development of pathologies in the fetus may also be an indication for screening. You don't need to have any health problems to be diagnosed. If a woman wishes to undergo screening to ensure the healthy development of the fetus, the doctor will definitely give a referral. The procedure is completely safe for both the woman herself and her unborn child.

What is seen on ultrasound in the second trimester

In, the fetus is fully formed, so doctors, having the results of examinations in their hands, can easily determine whether there are deviations or pathologies in its development. The second screening examination allows the doctor to identify many pathologies of the fetus, including:

1. malformations of the brain or spinal cord;
2. liver pathology;
3. anomalies of the gastrointestinal tract.
4. facial fissure;
5. heart defects;
6. defects of the limbs, torso.

Anomalies and defects that can be detected at the 2nd screening are often not subject to correction, and often serve as an indication for termination of pregnancy for medical reasons. In addition to pathologies, this research method determines the presence of markers of fetal chromosomal abnormalities, including:

1. developmental delay of the embryo;
2. a lot or lack of water;
3. pyelectasis;
4. ventriculomegaly;
5. underdeveloped length of the tubular bone;
6. vascular plexus cysts of the brain or spinal cord.

Thanks to the results, it is possible to identify other pathologies in the development of the fetus. Carrying out ultrasound diagnostics also allows you to get informative results on the development and growth of the fetus, assess the norms and deviations:

1. facial structure (size of the nasal bone, nose, ears, eyes);
2. size, weight of the fetus;
3. lung maturity;
4. the structure of the brain, heart, blood vessels, intestines and other internal organs;
5. the number of fingers on the upper and lower extremities;
6. thickness and degree of maturity of the placenta;
7. condition of the uterus and its appendages;
8. amount of amniotic fluid.

An ultrasound examination in the 2nd trimester allows you to determine the sex of the child with an accuracy of 90%, to identify the slightest disturbances in its development. After the screening has passed, all the results and transcripts are attached to the pregnant woman's card, and given to the doctor who leads the pregnant woman.

Screening of the 2nd trimester includes blood sampling from a vein, which is considered mandatory if a pathology is suspected. If the ultrasound results are satisfactory, there is no suspicion of an anomaly, a blood test may not be prescribed. Unlike the first trimester, a blood test in the 2nd trimester evaluates slightly different parameters, including:

1. the amount of human chorionic gonadotropin ();
2. free estriol;
3. indicators of alpha-fetoprotein (AFP);
4. inhibin A content.

Ultrasound and blood test during the second screening with an accuracy of 85% determine the dynamics of genetic abnormalities that were identified in the first trimester.

After passing all the tests, the results will be ready within a week. Only a doctor can decipher their results. With good screening results, the serum ACE level should be approximately 15 - 95 U / ml. With poor results, the protein level will be increased, which may be a sign of pathologies such as esophageal atresia, liver necrosis, and others. With a reduced protein, the risk of development or death of the fetus increases.

Screening indicators of the 2nd trimester are very important for a pregnant woman and fetus, so it is very important not only to properly prepare for examinations, but also to contact a qualified doctor for a transcript. It is important to understand that the life of the unborn child depends on the correct decoding.

How to prepare for the second perinatal diagnosis

Screening in the second trimester does not require special preparation, but still, in order to obtain reliable results, a woman needs to follow some rules.

1. Blood must be donated on an empty stomach. The use of any food, as well as liquids, can distort the results of the analysis. It is best to take a blood test in the morning.
2. 1 day before donating blood, you need to give up sweet foods, as well as foods that can cause an allergic reaction.
3. An ultrasound does not require any preparation. It is not necessary to fill the bladder. Diagnostics can be carried out at any time of the day.

Many doctors in the field of obstetrics and gynecology assure that a woman needs moral preparation, support from her relatives. It is important for a woman to tune in to positive results, to hope and believe in good results.

When does this study take place?

Screening in the 2nd trimester of pregnancy is recommended not earlier than the 16th, but not later. Many doctors recommend diagnosing at 17-18 weeks. It is during this period that it is possible to assess the condition of the fetus with high accuracy, to identify the slightest changes and pathologies in the development of the fetus.

In the presence of fetal abnormalities or suspicion of them, other additional diagnostic methods may be prescribed in the second trimester. A pregnant woman may be assigned a consultation with a geneticist and other specialists.

How the study is done

Ultrasound and blood tests should be performed at the same clinic on the same day. These diagnostic methods do not cause inconvenience to a woman, with the exception of those who are afraid to donate blood from a vein.

Ultrasound is performed by the transabdominal method, that is, the doctor applies the gel on the woman's stomach, using a sensor that is in contact with the skin, the doctor receives a picture on a computer monitor, from which he reads and records information about the condition of the fetus. The procedure takes 15 to 30 minutes.

After the results of the ultrasound, identifying any pathologies, the doctor sends the woman for a biochemical blood test. In the case when any pathologies are present, the woman in the laboratory donates blood from a vein. The sampling volume is from 3 to 5 ml.

The results of laboratory diagnostics need to wait for several days, while the transcript of the ultrasound can be obtained immediately after the procedure. After the results of the study, the doctor compares them with indicators of the norm and deviations. Against the background of the results of the examination, the specialist has the opportunity to get a complete picture, identify or exclude pathologies, and give useful recommendations. If necessary, a pregnant woman may be prescribed other methods of research.

Deciphering the results

Screening of the 2nd trimester consists of indicators, each of which has its own norm. In some cases, the results may deviate from the norm, since everything depends on the gestational age, the course of the pregnancy itself, and the characteristics of the female body.

Depending on the clinic, laboratory, the results may vary slightly, so doctors recommend to be examined only in clinics with a good reputation, where there is the latest equipment for laboratory and instrumental diagnostics.

The transcript of the ultrasound is compiled by the ultrasound specialist, after which it is transferred to the attending physician. Only a doctor can deal with tests, ultrasound results.

With increased or decreased rates, there is a risk of pathology in the fetus and woman.

• A low level of AFP is a sign, fetal death or an incorrect determination of the gestational age.
• Elevated AFP - malformations of the central nervous system, Meckel's syndrome, liver pathology (necrosis).
• Tall - or Klinefelter.
• Low - high risk.
• Reduced estriol - intrauterine infection, Down, fetoplacental insufficiency, risk of preterm birth.
• Elevated estriol - internal liver disease in the mother, multiple pregnancy or large fetus.

A blood test is not the final result for making a final diagnosis. If a pathology is suspected, amniocentesis is prescribed, which consists of piercing the abdominal wall, followed by amniotic fluid sampling. The results of this test give accurate results about the condition of the fetus with a probability of 99%.

Despite the alleged information about the indicators that may be present in the transcript of the analysis and indicate the pathology of pregnancy, the final decision is made by the doctor and only after repeated and additional tests.

Norms of indicators

To decipher the results of the examination, the doctor compares them with the norm table. If there are deviations, the specialist makes a conclusion, prescribes additional or repeated tests.

To decipher the screening of the 2nd trimester, the doctor can start from the norm table.

The table contains only estimated decoding parameters, which indicate the normal course of pregnancy and the absence of any pathologies in the fetus.

Important is not only the decoding of the blood test, but also the ultrasound examination. With normal performance, the decryption will contain the following parameters:

Pregnancy 16 - 17 weeks.

1. Fruit weight - 100 - 140 g.
2. The length of the fetus is 11.6 - 13 cm.
3. Abdominal circumference - from 88 to 131 mm.
4. Head circumference - from 112 to 145 mm.
5. Fronto-occipital size (LZR) - from 41 to 49 mm.
6. Biparietal size - from 31 to 37 mm.
7. The length of the leg bone is from 15 to 25 mm.
8. The length of the femur is from 17 to 28 mm.
9. The length of the bones of the forearm is from 12 to 21 mm.
10. The length of the humerus is from 15 to 25 mm.
11. The amniotic fluid index is 73–211.

Pregnancy 18 - 19 weeks

1. Fruit weight - 190 - 240 g.
2. The length of the fetus is 14.2 - 15.3 cm.
3. Abdominal circumference - from 104 to 154 mm.
4. Head circumference - from 141 to 174 mm.
5. Fronto-occipital size (LZR) - from 49 to 63 mm.
6. Biparietal size - from 37 to 49 mm.
7. The length of the leg bone is from 20 to 31 mm.
8. The length of the femur is from 23 to 34 mm.
9. The length of the bones of the forearm is from 17 to 26 mm.
10. The length of the humerus is from 20 to 31 mm.
11. The amniotic fluid index is 80–225.

The results of the research allow the doctor to determine important indicators in the development of the fetus are characteristic of. However, the final decision is made by the doctor individually for each patient.

Answers to the most common questions about the study

Women who are scheduled for screening in the 2nd trimester of pregnancy always experience anxiety, especially when it comes to possible pathologies. When consulting a doctor, women often ask doctors questions, which we will try to answer.

Question: What week of pregnancy is the best time to do the 2nd screening?

Answer: The examination of the 2nd screening can be carried out for a period of 16 - . The most accurate results can be obtained at 17-18 weeks.

Question: Is it necessary to donate blood from a vein during the 2nd screening?

Answer: If a pathology is suspected, it is mandatory. When the ultrasound results show normal values, there are no deviations from the norm, the pregnancy is proceeding well, the analysis may not be carried out.

Question: What is included in the 2nd screening examination?

Answer: Screening of the second trimester consists of ultrasound diagnostics and analysis of venous blood.

Question: Is it necessary to do a second screening?

Answer: If pathologies were detected during the first screening in the 1st trimester, the pregnancy is difficult, the woman is over 35 years old or has a history of chronic diseases, then it is necessary.

Screening price 2nd trimester

The cost of the 2nd screening directly depends on the clinic, possible additional research methods. The price for a complete examination can range from 2500 to 4000 yew. rubles. In some public clinics, you can undergo the procedure for free, but given that medical centers, private clinics and laboratories have more modern and accurate equipment, if you suspect a pathology, it is better to turn to them.

Screening of the 2nd trimester is one of the important research methods that allow to identify anomalies in the development of the fetus in time. In case of poor results, malformations or defects in the development of the fetus, it is recommended to terminate the pregnancy for medical reasons.

During pregnancy, doctors monitor the expectant mother and baby. In order not to miss dangerous diseases that may appear in the fetus, specialists send pregnant women in each trimester for screening. This is an exciting process, but it is better to pass the diagnosis.

2nd trimester screening

The purpose of diagnostics is to analyze the condition of a pregnant woman, identify malformations, physiological abnormalities in a child that could be missed at the first screening or could not be detected in the early stages. Also, the doctor is tasked with confirming or refuting the diagnoses made after the previous examination.

Depending on the indications, the specialist may prescribe one of the diagnostic options:

• ultrasound - the doctor conducts an examination on an ultrasound preparation, determines the parameters of the child, checks for the presence of pathologies, developmental anomalies;
• biochemical - blood is taken from pregnant women to determine the indicators of a number of hormones;
• combined - ultrasound and a biochemical blood test are performed.

As a rule, the expectant mother is sent for ultrasound or combined screening. But a pregnant woman, if desired, can be examined in different places. For example, in a antenatal clinic to do an ultrasound diagnosis, and in a private clinic to pass a biochemical blood test.
At screening of the 2nd trimester, a biochemical blood test may be prescribed for special indications

Purpose of diagnostics

If the pregnancy proceeds calmly, in antenatal clinics they often give a referral only to undergo an ultrasound scan.

Both times when I was expecting a baby, we were sent to the regional center for the first screening. They did an ultrasound and took blood for a biochemical analysis (to detect pathologies). The second screening took place in the antenatal clinic in the city where I live, and the only appointments were ultrasound and blood tests: general, HIV, RW, hepatitis. Doctors did not offer me to do a biochemical analysis. Perhaps because I was not at risk and the results of the first screenings were normal.

There are a number of indications in which a woman, in addition to ultrasound, must donate blood for biochemical parameters:

• mother's age is more than 35 years;
• the child was conceived by parents who are close relatives of each other;
• poor heredity in the parents of the child - chromosomal pathologies in the family or there are already children born with genetic diseases;
• the threat of termination of pregnancy;
• tragic ending of previous pregnancies:
  • freezing of the fetus;
  • miscarriages;
  • stillborn fetus;
  • premature birth;
• taking medications that should not be taken while carrying a child;
• drug addiction, alcoholism;
• difficult working conditions;
• expectant mothers exposed to radiation before conception and in the first weeks of pregnancy;
• genetic diseases of the mother, inherited:
  • diabetes;
  • bronchial asthma;
  • cirrhosis, etc.;
• infectious or viral diseases of the mother during pregnancy;
• oncopathology of the mother;
• pathologies in the development of the fetus, identified at the first screening.

The expectant mother has the right not to undergo diagnostics, for this it is necessary to write a waiver, the form for which can be asked from the doctor.

Many specialists do not welcome the decision to skip the examination, because sometimes the problems identified during these periods can be successfully solved.

Still, I won my doctor. In my first pregnancy, after reading everything in the world and realizing what kind of analysis it was, I wrote a conscious refusal to screen. Now the second pregnancy. During this time, she moved - the doctor is different. To my words about the refusal, she categorically said that now it’s impossible, blah blah, a lot of downs ... well, and everything in the same spirit. This was at the first consultation. Before the second one, I refreshed this topic in my memory (after all, 4.5 years have passed!), I decided that I WILL NOT do this analysis. Half the night I was looking for the right words, considering the tactics of the conversation From whining to threats It worked! Which is why I am very glad. You can refuse any intervention, no matter what the doctor says, and what internal instructions she would not follow! I wrote a written refusal of the first screening (I will write the second later) Let the geneticists at least rest on me (at the same time, maybe until they come up with a more accurate analysis ) and ultrasound (possible) too.

https://www.babyblog.ru/community/post/living/1706857

Terms of the study

A pregnant woman is sent for examination from the 16th week. The best times for screening are 16–20 weeks. Some doctors issue a referral until the 24th week.

According to my recollections, in the first pregnancy I was sent for an ultrasound at the 21st week, in the second - at the 20th week.
2nd trimester screening required from 16 to 20 weeks of pregnancy

Ultrasound and biochemical blood test

On ultrasound, doctors examine the condition of the expectant mother and baby.

In women, the specialist evaluates:

• placenta status:
  • location;
  • thickness;
  • degree of maturity;
• condition of the female genital organs:
  • uterus;
  • appendages;
  • cervix;
  • ovaries;
• amniotic fluid volume.

The specialist looks at the child:

• the structure of internal organs;
• fetal parameters (fetometry):
  • growth;
  • circumference of the head and abdomen;
  • thigh length, calf length, etc.

A biochemical blood test includes the following indicators:

• the level of chorionic gonadotropin - hCG. This hormone allows you to save pregnancy, affects its course. The results of the analysis of this indicator can provide information about possible pathologies;
• estriol level - E3. This hormone affects the formation of ducts in the mammary glands. Its indicators indicate the state of the uteroplacental blood flow;
• level of alpha-fetoprotein - AFP. It is a protein in the blood serum of the embryo. Provides the child with nutrients. The level of this hormone provides information about the development of the fetus;
• the level of inhibin A. This analysis is done if there is an indication for this. If the fetus has syndromes caused by chromosomal abnormalities, the level of the hormone increases. A change in the level of concentration may also indicate fetoplacental insufficiency.

Screening preparation

No preparation is required for an ultrasound. You do not need to drink water, as is necessary for the first screening. But before biochemical analysis, you should:

• stay on a diet for a day - do not eat fatty and fried foods, seafood, citrus fruits, chocolate and other allergenic foods;
• do not take medication (if possible) the day before blood sampling;
• do not eat on the day of the test;
• drink still water, but not much.

Cost of diagnostics

If a woman is registered in a antenatal clinic, then the doctor must issue a referral for a free examination.

When I was pregnant, the antenatal clinic, to which I was attached, gave expectant mothers a referral for ultrasound for free. Both times the screening of the 2nd trimester passed for me at no financial cost.

Private pregnancy clinics can also provide 2nd trimester screening services. The approximate cost of diagnostics is from 1500 to 5000 rubles.

Deciphering the results

Screening passed. The expectant mother receives a conclusion in her hands, in which the results of the examination are written. Some indicators can be understood without having a special education, but for some values, many questions arise.

ultrasound

If you carefully read the doctor's conclusion and decipher the results of the ultrasound scan, you can get an approximate picture of the course of pregnancy and the development of the baby. Consider the parameters and their norms, which experts indicate in the epicrisis.

Fetal weight and height

An important indicator informing about the development of the child in the womb:

• too little weight of the fetus indicates the likelihood of syndromes associated with a violation of the number of chromosomes, for example, Edwards syndrome or Patau syndrome;
• critically low weight can be a sign of food or oxygen starvation, slowing down the development of the fetus and fading pregnancy;
• excess weight indicates the possible development of pathologies of the central nervous system or edema, which is typical for hemolytic disease (incompatibility of the blood of the fetus and mother).

Table: approximate indicators of fetal weight and height

Biparental head size (BDP)

This indicator is obtained by measuring the distance from one temple to another. The line joining both parietal bones should pass through the center of the head perpendicular to the line drawn from the frontal to the occipital bone.

This parameter determines the gestational age, since this indicator indicates the timing more accurately than others.

Differences in BDP indicators from the norm can tell a lot:

• with high BDP data, the specialist correlates this value with other parts of the body. If all indicators are evenly distributed, then there is reason to assume that a woman will have a large child;
• with an increase in only the parameters of BDP, fronto-occipital size (LZR) and head circumference (OH), we will already talk about the diagnosis of hydrocephalus, the cause of which could be an intrauterine infection. These data may also indicate a tumor or cerebral herniation;
• if the indicators of BPR, LZR and OG are below average values, and the rest of the parameters are normal, then most likely the child has microcephaly, a disease characterized by a small brain mass and mental retardation;
• if the BDP data is significantly less than the norm, they speak of intrauterine growth retardation syndrome (SZVR).

Table: BDP indicators

Fronto-occipital size (LZR)

This indicator is obtained by measuring the distance from the forehead to the back of the head. The line connecting the frontal and occipital bones should pass through the center of the head perpendicular to the line drawn from temple to temple.

LZR indicators are correlated with BPR indicators. Then a diagnosis is made if there is a deviation from the norm. The BDP parameters still remain the leading indicators.

Table: LZR indicators

Head circumference and shape

Together with BPR and LZR, the doctor looks at the circumference and shape of the head. In a healthy child, the head has an oval, rounded or oblong shape. A strawberry-shaped or lemon-shaped head indicates a genetic abnormality in the fetus.

Table: head circumference indicators

Thigh, calf, shoulder and forearm length

In diagnostics, these parameters must also be determined. They allow you to give a general picture of the correct development of the skeleton. The specialist can send for an additional examination if the ultrasound shows a sharp shortening of all limbs or different lengths of the arms and legs.

Table: indicators of the length of the thigh, lower leg, shoulder, length and forearm

Parameter name	Gestational age	Norm indicators (average values, mm)	Lower limit, mm	Upper limit, mm
Thigh length	16 weeks	21	17	23
	17 weeks	24	20	28
	18 weeks	27	23	31
	19 weeks	30	26	34
	20 weeks	33	29	37
Calf length	16 weeks	18	15	21
	17 weeks	21	17	25
	18 weeks	24	20	28
	19 weeks	27	23	31
	20 weeks	30	26	34
Shoulder length	16 weeks	15	12	18
	17 weeks	18	15	21
	18 weeks	20	17	23
	19 weeks	23	20	26
	20 weeks	26	22	29
Forearm length	16 weeks	18	15	21
	17 weeks	21	17	25
	18 weeks	24	20	28
	19 weeks	27	23	31
	20 weeks	30	26	34

Nose bone length

Scientists have recently discovered that there is a relationship between the size of the nasal bone and physical development. If the indicators do not meet the standards, the doctor can send the expectant mother for examination of fetal chromosomal abnormalities.

Table: indicators of the length of the nasal bone

Abdominal circumference

An important indicator that allows timely diagnosis of SZVR. If the data is significantly below the average, the specialist can make this diagnosis.

Table: indicators of abdominal circumference

Amniotic Fluid Index (AFI)

This index shows the volume of amniotic fluid:

• in case of deviation from the average values, treatment is prescribed;
• at low rates, oligohydramnios is placed. With this diagnosis, there is a threat of infection;
• at high rates, polyhydramnios is placed. It threatens with an incorrect presentation of the fetus, stillbirth, bleeding in the mother and speaks of an infection that is occurring or has taken place.

Table: IAI indicators

Other indicators

Doctors watch how the baby's organs develop:

• brain;
• heart;
• lungs;
• intestines;
• spine;
• bladder;
• stomach;
• kidneys.

Specialists check the child:

• the presence of ears;
• no cleft mouth;
• eye development;
• correct number of fingers and toes.

On ultrasound, the doctor determines the heart rate. After the 11th week, the normal should be 140-160 contractions per minute.

When an ultrasound scan took place in our antenatal clinic, the doctor always turned on the speakers so that you could hear how the baby's heart was beating. This sound has always caused inexpressible sensations and had a calming effect on me. For me, these heart rhythms meant that everything was fine with the child.

Ultrasound Specialist:

• determines the state of the placenta. It can be attached to the posterior or anterior wall of the uterus. It is important that there is no premature maturation of the placenta, otherwise the fetus may have hypoxia;
• evaluates the tone of the uterus. Hypertonicity should not be;
• looks at the umbilical cord, its thickness, the number of vessels, which should be three, the quality of blood flow through the vessels;
• checks the cervix, in which the internal os must be closed;
• evaluates the viability of the suture if a caesarean section was performed before this pregnancy.

At these times, you can find out the sex of the unborn child.

Very often, parents already at the second screening find out who will be born to them: a boy or a girl. But there are times when the child lies in such a way that the floor cannot be seen. For example, my sister found out only after the third screening that she was expecting a son.

Biochemical screening

The indicators obtained as a result of blood sampling also carry a lot of information.

AFP

Indicators can be above and below average:

• above average may indicate:
  • Shereshevsky-Turner syndrome,
  • large fruit,
  • multiple pregnancy,
  • viral liver damage in the fetus;
• below average may indicate:
  • Down Syndrome,
  • Edwards Syndrome,
  • developmental delay,
  • risk of preterm birth.

Table: AFP values ​​are normal

EZ indicator

If the hormone level is too high, as a rule, there is nothing to worry about. Most likely, a pregnant woman has a large fetus or a multiple pregnancy. A low level may indicate Down's syndrome, a viral infection in the baby, or the risk of early birth.

Table: normal free estriol values

HCG indicator

If the indicators are not normal, there is a high probability that the fetus has a disease associated with chromosomal abnormalities.

Table: hCG values ​​are normal

Inhibin A

The level of this hormone changes all 9 months of pregnancy. At the time of screening for the 2nd trimester, its level ranges from 50–324 pg/ml.

Normally, its indicator should be 2 MoM. Exceeding this level gives reason to suspect the development of a tumor, the formation of placental insufficiency, Down syndrome. There were cases when other values ​​corresponded to the norm, except for Inhibin A, and as a result, the child was born healthy. Therefore, this indicator must be correlated with other screening data.

MoM factor

The MoM coefficient is understood as an indicator that shows the degree of deviation of data from the mean value (median).

MoM = The value of the indicator in the patient's blood serum / The value of the median indicator for the gestational age. If the MoM value for any indicator is close to one, this means that the value is close to the average in the population; if it is above one, it is above the average; if it is below one, it is below the average. When calculating risks, MoM is adjusted taking into account various factors (body weight, smoking, IVF, race, and so on). MoM calculation is carried out using special software.

Olga Laskina, doctor of clinical laboratory diagnostics

https://www.baby.ru/sp/6235862/blog/post/10093759/

The optimal indicators for the results of the second screening are determined by the following values:

• the lower limit of the norm - 0.5;
• the optimal indicator is 1;
• the upper limit of normal is 2.5.

Serious deviations from the norm give reason to suspect pathologies in the fetus.

The result of the examination is recorded as a fraction, for example, 1:700.

Table: overall screening results at MoM

Table: diseases that can be assumed based on the results of biochemical analysis

Pathologies that can be detected on 2nd trimester screening

On the second screening, the following pathologies can be detected.

Down syndrome

One of the most common diseases caused by a violation of the number of chromosomes. Such people have a Mongoloid incision of the eyes, a flat bridge of the nose, a flattened face and the back of the head. There is a lag in development and weak immunity.
Children with Down syndrome can be prepared for independent life in society

People with this particular syndrome, contrary to popular belief, are non-aggressive, kind, friendly, affectionate, and many children are teachable. If a child grows up in a full-fledged family, it is possible to prepare him for a full life.

Edwards syndrome

A disease that is also caused by chromosomal abnormalities. The appearance of such children is distinguished by the non-standard shape of the skull, auricles, and lower jaw. They have fusion of fingers, there are anomalies in the development of the genital organs.
Edwards syndrome - a disease caused by chromosomal abnormalities

A child with such a disease lags behind in physical development, has a clubfoot, abnormal muscle tone, and abnormal emotional reactions.

Patau Syndrome

Chromosomal pathology, characterized by multiple diseases of the musculoskeletal and nervous system, eyes, heart and other organs. Often, with such a syndrome, a child dies in the womb, because with this disease, many defects appear. Children lag behind in physical and mental development.

Anencephaly

The disease is characterized by the absence of the brain. The disease is incompatible with life. Children born with this defect live for several hours, rarely days. There are only a few cases where children with this disease lived for several years.
Very rarely, a child diagnosed with anencephaly can live for several years.

It is simply impossible to determine how the fetus grows and develops without performing a series of studies. A very important medical method of such diagnosis is screening of the 2nd trimester of pregnancy.

Enter the first day of your last menstrual period

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 30

What it is?

Doctors call screening a whole range of examinations, which is necessary in order to identify various developmental anomalies in the fetus, as well as to determine how well it develops in the mother's womb. Pregnancy is a unique period in the life of every woman. At this time, the hormonal background changes significantly. This leads to the fact that the basal level of hormones changes. Also, specific biochemical markers may appear in the blood, which indicate the possible development of genetic and chromosomal pathologies.

In each of the periods of bearing a baby, pathologies manifest themselves in different ways. They can only be determined by laboratory diagnostics and ultrasound. Such studies are prescribed by an obstetrician-gynecologist. The expectant mother learns about screening, usually at the very first visits to the women's clinic. Screening during pregnancy is a recommended procedure. Not all women decide to go through it.

Quite often, only expectant mothers with any concomitant diseases of the internal organs undergo prenatal screening.

The introduction of prenatal screening in our country is relatively recent. A frightening demographic situation led to the development of such recommendations by doctors. Doctors note that the introduction of prenatal screening has significantly reduced maternal mortality. Thanks to this diagnostic complex, doctors began to identify dangerous genetic anomalies at the earliest stages of their formation.

The second trimester is the period when the embryo has moved on to the next stage of its development. At this time, the future baby of the doctor is already being determined as a fetus. The child continues to undergo differentiation of all vital systems of the body. This time is no less important than the first trimester of pregnancy. A full-fledged second screening includes a set of general clinical and biochemical tests, hormonal studies, and is also supplemented by mandatory ultrasound. In some cases, doctors may slightly expand the list of necessary tests.

Quite often this happens in a situation where some deviations from the norm were found in the future mother during the screening of the 1st trimester of pregnancy.

Many mothers believe that screening can prevent the development of congenital genetic diseases in their babies. It should be noted right away that, unfortunately, this is not the case. It is possible to prevent the appearance of chromosomal pathologies in a baby at the stage of preparation for pregnancy..

If conception has already occurred, then it is no longer possible to influence the formation of a specific genetic disease. However, it is quite often possible to identify certain pathologies with the help of screening. Such dangerous diseases as Down's disease, Edward's syndrome, Patau's syndrome and many other diseases can be determined using a specific diagnostic complex, which is carried out in the 2nd trimester of pregnancy. Screening also allows you to identify various malformations and anomalies in the structure of tubular bones.

Quite often, these tests also reveal congenital metabolic diseases, such dangerous pathologies include galactosemia, phenylketonuria, cystic fibrosis, and many others.

Dates

Doctors have established several decreed periods of pregnancy, in which it is most rational to do screening. In each of the trimesters of bearing a baby, there is one such diagnostic complex. Terms of passage are determined for all women. There are also certain clinical situations where they may be slightly shifted.

In this case, the specific dates for screening are determined by the obstetrician-gynecologist observing the patient.

In most situations, a set of studies is carried out at 16-20 weeks of pregnancy. As an exception, screening can be carried out after 21 weeks. Usually this situation occurs when a pregnant woman has any neoplasms in the ovaries. With these pathologies, the hormonal background changes significantly. To obtain more accurate results of biochemical analyzes, screening is postponed for 1-2 weeks.

Many mothers believe that ultrasound should be done on the same day as going to the laboratory. Doing this is completely optional.

Even a few weeks can pass between blood tests and ultrasound examination, this situation is quite normal.

Who should be screened?

Obstetrician-gynecologists recommend such a complex to all women bearing babies, however, there are certain groups that simply need to be screened. Women who have indications for the study should not skip the prenatal diagnosis complex. This can lead to the fact that doctors simply do not find out in a timely manner about the presence of dangerous pathological conditions in the expectant mother and her baby. Doctors identify several decreed categories of women who simply need to be screened.

These groups include the following:

• Future mothers who conceived a baby after 35 years;
• Pregnant women with congenital malformations or a burdened family history of genetic or chromosomal diseases;
• Future mothers who have abnormalities in tests or ultrasound during 1 pregnancy screening;
• Pregnant women suffering from severe diseases of internal organs;
• Expectant mothers who have a burdened course of the 1st trimester of pregnancy with frequent threats of spontaneous miscarriage;
• Pregnant women who are forced to take immunosuppressive or hormonal medications for medical reasons while carrying a baby.

If the expectant mother during the 1st screening or later on ultrasound, doctors detect dangerous pathologies of fetal development, then in this case she is sent for additional diagnostics to the perinatal center. There, more experienced doctors perform expert-level ultrasound examinations.

In some situations, pregnant women with certain medical conditions are screened only in such perinatal centres.

Training

To obtain reliable and accurate results, it is very important for a future mother to prepare properly. A few days before the delivery of biochemical tests, she should definitely follow a lipid-lowering diet. It implies a restriction in the daily diet of all fatty and fried foods. Fast food, smoked meats and pickled dishes are also completely excluded. Dinner on the eve of the study must be light. It is optimal if it consists of a protein dish, complemented by a side dish of any cereal. Vegetables and fruits should be limited before ultrasound, they can lead to increased gas formation, and the presence of gases in the abdomen will not allow the ultrasound doctor to examine the fetus and all membranes well.

Also, 2-3 days before the ultrasound examination, legumes and all types of cabbage are necessarily excluded. The use of kvass or carbonated drinks also significantly increases gas production. It is better that on the eve of the scheduled test and ultrasound, all food should be as light as possible, but nutritious.

It is very important for a pregnant woman to eat enough protein even before laboratory tests.

Physical activity can also lead to inaccurate results. Doctors have long noticed that simply climbing stairs can provoke a change in biochemical parameters. In order for the results of laboratory tests to be accurate, the expectant mother should limit all physical activity. In this case, it is better to postpone cleaning the apartment or attending yoga for pregnant women for a few days after the screening.

Biochemical tests should be done necessarily on an empty stomach. Some experts allow expectant mothers to drink some water before the study. Do not eat breakfast before going to the laboratory.

Testing should be done in the morning. Studies conducted in the evening give less truthful results.

Currently, doctors recommend that expectant mothers should limit all highly allergenic foods before taking biochemical tests. This is due to the fact that every day there are more and more scientific studies that indicate that such food can affect the receipt of reliable results.

For a week before screening tests for the 2nd trimester, it is better to exclude all citrus fruits, seafood, chocolate and honey from your menu.

Analysis norms

Biochemical screening of the 2nd trimester has a very important diagnostic value. The results of the obtained blood tests are not yet a diagnosis at all, they only help doctors orient themselves in the possible pathologies of the course of pregnancy and anomalies in the development of the fetus at this stage of its intrauterine development. HCG is an important laboratory marker that allows you to identify certain "hidden" pathological conditions. Its dynamics throughout pregnancy changes. In the first weeks of intrauterine development of the fetus, the concentration of this hormone in the blood is maximum. Then, over time, it begins to decline.

Before childbirth, the concentration of hCG in the blood drops rapidly.

At the 16th week of pregnancy, normal levels of hCG in the blood reach 4.7-50 ng / ml. By week 20, this value is already rising above 5.3 ng / ml. Quite often, an increase in hCG occurs with multiple pregnancies. A significant excess of this indicator may indicate the possible development of Down's disease or Edwards syndrome.

Alpha-fetoprotein is another specific pregnancy hormone that is used to assess the intrauterine development of an unborn baby. It is formed due to the gastrointestinal tract and liver of the fetus. By the end of 10-11 weeks, it begins to flow through the common uteroplacental blood flow system and into the maternal body. The normal values ​​​​of this indicator at 16-19 weeks of gestation are 15-95 units / ml.

Free estradiol is the third indicator that shows how well a particular pregnancy is going. To a greater extent, it reflects the functional ability of the placenta. The normal course of pregnancy is accompanied by a gradual increase in this hormone in the blood of the expectant mother. By week 16, the values ​​​​of this hormone are 1.17-5.5 ng / ml.

To assess the risk of various chromosomal pathologies, doctors are increasingly prescribing a non-invasive hemotest to expectant mothers. It allows you to identify the DNA of the fetus and assess the presence of any genetic diseases. Significant disadvantages of this study are the possibility of conducting it only in the largest Russian cities and the high cost.

Such studies are prescribed only for strict genetic medical indications.

Interpretation of ultrasound results

The second trimester of pregnancy is the time when it is already possible to determine not only the outlines of the fetal body, but also evaluate the work of its internal organs. For this, doctors have developed a number of special indicators. They help doctors conduct a more comprehensive assessment. Expectant mothers should remember that the conclusion of an ultrasound scan is not a diagnosis. It only describes all the visual changes that the specialist saw during this study.