Screening of the second trimester: when done, decoding of the results, indicators of the norm and deviations. How many weeks the second screening is carried out: terms, norms and interpretation of indicators during pregnancy Screening transcript of the 2nd trimester table

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 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:

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 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:

AFP (α-fetoprotein);
E3 (estriol);
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, and its viability.

Standards for screening indicators by week

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

Index	16 weeks	20 weeks	22 weeks
OG	112-136 mm	154-186 mm	178-212 mm
DP	15-21 mm	26-34 mm	31-39 mm
DPP	12-18 mm	22-29 mm	26-34 mm
DB	17-23 mm	29-37 mm	35-43mm
coolant	88-116 mm	124-164 mm	148-190 mm
DG	15-21 mm	26-34 mm	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.

Screening in the 2nd trimester is a mandatory fetal examination that every pregnant woman undergoes. The procedure is prescribed from the 19th to the 23rd week of pregnancy.

In terms of the timing of the second screening, it falls within the period of 19–23 weeks. The study is considered complex, since the pregnant woman undergoes an ultrasound scan and takes a biochemical blood test. Sometimes a woman may refuse a blood test. But there are medical indications, according to which blood must be taken for examination:

the age of the future mother is more than 35 years;
there is a threat of termination of pregnancy;
if a woman's other pregnancies ended in miscarriages, the fetus died, there were premature births, the birth of a dead child;
the pregnant woman used illegal drugs while carrying a child;
the expectant mother suffers from drug addiction, alcoholism or smokes;
mother and father of the child are related by blood;
a woman has been diagnosed with cancer;
a pregnant woman works in difficult working conditions;
one of the parents was diagnosed with a genetic disease, for example, diabetes mellitus;
the first time a blood test and an ultrasound examination showed a congenital disease in the fetus;
the expectant mother suffered an infectious or viral disease before 19 weeks;
the pregnant woman was previously irradiated;
the closest relatives of the woman suffer from chromosomal diseases, or the family had a child with such a pathology.

Fetal weight and height

One of the important indicators in the results of the second screening is the weight and height of the child:

Very low weight is often associated with food starvation and fetal hypoxia. Because of this, there is a violation of the development of growth and weight gain. Therefore, the pregnancy freezes.
A small weight that does not correspond to the deadline indicates possible chromosomal diseases: Down syndrome, Edwards.
Too much weight is characteristic of pathologies of the central nervous system. Another sign may indicate internal edema in hemolytic disease, when the child's blood is incompatible with the mother's.

According to the ultrasound of the 2nd trimester, the indicators of the norm of growth and weight look at the table with the decoding:

Nose bone length

The length of the baby's nose bone is related to physical development. If the parameter does not meet the standards, the pregnant woman is sent to be examined for the presence of chromosomal diseases in the fetus. By the 20th pregnancy on the 2nd screening ultrasound, the nasal bone reaches an average length of 7 millimeters.

Biparietal head size - BDP

On the 2nd screening, it indicates the distance from one temple of the head to another. This line connects the parietal bones. It should be perpendicular to the line that is drawn between the forehead and the back of the head. The parameter characterizes the exact gestational age.

If individual parameters differ from the established norm, the following diagnoses are possible:

Large BDP correlates with other limbs. With a uniform distribution of parameters, a large child is diagnosed, which is not good for natural childbirth.
The syndrome of intrauterine growth retardation is given to those who have BDP several times behind the norm.
Hydrocephalus is detected at screening in the 2nd trimester if BDP is increased, the size of the forehead and occiput along with the circumference of the fetal head. The disease occurs due to infection.
Microcephaly is diagnosed with low levels of BDP, OG and LZR. The disease is characterized by a small brain mass with subsequent mental retardation.

The values of the BDP norm in the table, which are considered in the results of ultrasound of the 2nd screening:

Fronto-occipital size - LZR

Ultrasound at the 2nd screening assesses the fronto-occipital size, the distance between the forehead and the back of the head. The connecting line between the frontal and occipital bones normally passes through the center of the head and becomes perpendicular to the line that runs from one temple to the other.

LZR is always evaluated together with BDP. After the diagnosis is established in case of deviation from the standards. Consider the norms of the parameter at the 2nd screening by weeks of pregnancy:

weeks	Norm parameters, measured in millimeters	Lower level	Upper level
18	54	49	59
19	58	53	63
20	62	56	68

Head circumference and shape

In addition to BPR with LZR, the sonologist measures the shape and circumference of the child's head. A completely healthy child on the 2nd screening ultrasound has a rounded head shape. Other forms are considered deviant. Normal head circumference by 20 weeks of pregnancy is 170 millimeters.

Thigh, calf, shoulder and forearm length

Calculation of the sizes of hips, shins, shoulders and a forearm is obligatory. The sonologist prescribes an additional examination with a strong shortening of the limbs and a discrepancy between the length of the arms and legs. Consider a table with the norms of indicators of the length of the child's limbs at the screening of the 2nd trimester:

Indicator length	weeks	Standard in millimeters	Lower level	Upper level
Hip	18	27	23	31
	19	30	26	34
	20	33	29	37
Shin	18	24	20	28
	19	27	23	31
	20	30	26	34
Shoulder	18	20	17	23
	19	23	20	26
	20	26	22	29
Forearm	18	24	20	28
	19	27	23	31
	20	30	26	34

Abdominal circumference

Syndrome of intrauterine growth retardation is detected by the circumference of the abdomen. When lagging behind the average norms, the doctor makes this diagnosis. With normal development at the screening of the 2nd trimester, the circumference of the abdomen of the fetus averages 15 centimeters.

Amniotic Fluid Index - AFI

IAI is responsible for the volume of amniotic fluid in the bladder. Normally, by the 20th week, they are 140-214 millimeters.

With a low index on the second screening ultrasound, the doctor puts oligohydramnios and the threat of infection. With a high index, there is a risk of malpresentation of the fetus and stillbirth due to free flow: the child may become entangled in the umbilical cord and suffocate.

To view what a child looks like on an ultrasound:

Biochemical screening

Biochemical blood screening in the 2nd trimester is done for a fee according to indications. The test is considered triple, since 3 main markers are determined:

Alpha-fetoprotein. The fetus has been producing this protein since 5 weeks. The main task of the substance is to transport useful trace elements and protect the child from the aggressive reaction of maternal immunity. The norm of the hormone content by the 20th week is in the range of 27–125 units per milliliter.
free estriol. Even before fertilization, it is produced in the ovaries, but in small quantities. During pregnancy, the level of free estriol increases due to synthesis in the placenta and liver of the child. The hormone prepares the body of the expectant mother for lactation. HCG and free estriol are always measured at the beginning of the term. The norm is 7.6–27 units of nmol per liter.
HCG. The hormone is synthesized only in pregnant women. A large concentration is observed in the first trimester. By the 21st week, the indicator drops to the limit of 1.6–59 microscopic units per milliliter.

In addition to the main listed parameters, in the biochemical screening of the 2nd trimester, inhibin A is calculated in MoM coefficients. Its index during normal intrauterine development is 2 MoM. This coefficient is considered the degree of deviation of the received information from the average values.

Possible diseases according to the results of biochemical analysis

The purpose of a biochemical blood test is to determine the child's chromosomal diseases. In Down's syndrome, a characteristic sign is an elevated level of hCG at screening of the 2nd trimester and a decrease in blood levels of other hormones.

AFP, EZ, or free estriol are elevated in the presence of Meckel's syndrome and liver necrosis. HCG is normal. AFP and other parameters decrease below the established norm in Edwards syndrome.

Free estriol decreases after a course of antibiotics, with the development of intrauterine infection and placental insufficiency. A pregnant woman may be prescribed an amniotest, a puncture in the abdominal wall to take a sample of amniotic fluid. This is done to accurately confirm or refute previously diagnosed diagnoses.

Pathologies that can be identified

In the 2nd trimester, screening during pregnancy is done as a preventive measure to detect chromosomal abnormalities. Ultrasound reveals such pathologies as Edwards.

In the first case, a characteristic feature is the nasal bone, which, in case of illness, is much less than the lower limit of the norm. In the second case, the weight of the child is considered: with a disease, it is very small. Consider other possible pathologies:

Trisomy 13, or Patau's syndrome, is a rare disease that is detected on ultrasound in the second trimester when the skull is formed incorrectly, deformities of the feet, hands, and disorders in the structure of the brain.
Back Bifida, spina bifida, on ultrasound diagnostics is shown in the form of open vertebrae from behind. The deformity occurs due to a disrupted formation of the neural tube.
Anencephaly is usually diagnosed in the first trimester. But, if the study was skipped, intrauterine defect is detected at the 2nd screening. On ultrasound, the child is partially or completely absent brain lobes.
Shereshevsky-Turner syndrome on prenatal ultrasound screening of the 2nd trimester is characterized by a wide chest, curvature of the limbs, short fingers, edema, low body weight and short stature.
Klinefelter's syndrome with ultrasound diagnosis is rarely detected. But, if the doctor suspects a pathology, he will direct the pregnant woman to undergo an amniocentesis.

What can affect the results

Results of 2nd trimester perinatal screening depend on:

Errors in determining the timing of pregnancy.
Presence of bad habits in a pregnant woman (more often smoking).
Periodic stress.
Bearing multiple fruits. In this case, the rate of hormones is calculated individually for a double, triple pregnancy.
Reception of hormonal drugs during the gestation period.
Hormonal background, changing due to the age of the mother over 35 years.
Pregnancy after IVF. Before this, hormonal therapy is performed, the results of which are stored until the 2nd screening.
Severe obesity. The disease produces female sex hormones that change the composition of the blood.

Screening in the 2nd trimester is a responsible procedure that a pregnant woman should not refuse. The health and further development of the child depends on this.

We offer you to see answers to frequently asked questions on the topic of the 2nd trimester in an interview with a doctor:

How did you go about your 2nd trimester screening? Share it in the comments. Tell your friends about the article on social networks. Be healthy.

If a woman undergoes the first large-scale study at 10-13 weeks, then screening of the 2nd trimester is carried out a little later. It also includes a biochemical blood test and ultrasound, but they are done at different times.

Blood tests

In principle, during the 2nd screening, all the studies that were carried out at the very beginning of pregnancy are done. Check the level of PAPP-A, the hCG hormone. Only in the second trimester are added tests for inhibin A and free estirol. Also, in the middle period of pregnancy, a woman undergoes a second ultrasound procedure.

When a second pregnancy screening is done, not all of these blood counts may be checked. If everyone is included in the survey, it is called a quadruple test.

To understand why blood is examined in such detail, you should understand the values \u200b\u200bof indicators for a successful pregnancy. Depending on the results, the woman may be placed at risk.

HCG is human chorionic gonadotropin. This substance is called the main hormones of pregnancy. If its level is too high, then the doctor has the right to suspect the development of various syndromes such as trisomy in the fetus. These include, for example, Down syndrome. If the blood test showed low values, the fetus in the second trimester may be diagnosed with Edwards syndrome.

The PAPP-A protein, or AFP, is an equally important marker of various diseases. Although it gives the most accurate results during the first trimester. It is at the period of 10-13 weeks of pregnancy that the doctor can most accurately determine the development of syndromes by the underestimated content of this protein in the mother's body. As a marker of trisomy 21, or rather Down's syndrome, it is rarely considered for a period of 14 weeks. In other words, its amount in the blood of a woman with a healthy fetus and a fetus with trisomy will be identical.

And yet, the doctor may talk about other malformations with an elevated level of AFP in the second trimester. So, for example, the results of tests may indicate an abnormal development of the neural tube or a pathology of the brain. Also, elevated AFP levels often indicate the development of multiple pregnancies.

Such an indicator as free estriol is checked only in the second trimester. This is one of the main hormones that affects the growth of the uterus and the preparation for lactation. Thanks to the estriol level, you can also find out how the adrenal glands work in the fetus.

Usually, estriol levels depend on many factors, one of which is the use of antibiotics in the second trimester. Therefore, when a second screening is done during pregnancy, this must be taken into account. A low level of this hormone may indicate the presence of chromosomal abnormalities in the fetus, problems with the adrenal glands, or indicate fetoplacental insufficiency. If the level is high, the specialist puts fetal liver disease, a discrepancy between its weight and the gestational age, or the development of multiple pregnancies.

During the quadruple test, the level of inhibin A is also checked. This protein hormone is produced by the placenta. According to its indicators, it is rather difficult to accurately assess whether the fetus actually has developmental complications. Usually, results with an increased content in the blood indicate Down and Edwards syndrome, but in medical practice there have been cases when healthy children were born with such indicators. Inhibin A is dependent on other indicators, which gives a blood test.

All results are analyzed using a special computer program, and then the doctor checks them again. This takes into account not only indicators, but also other factors such as nationality and bad habits, prescribed medications and genetic diseases.

Of course, it cannot be argued that the quadruple test is able to say with accuracy whether the fetus has a particular disease. All indicators and their results are considered combined together with the data of the first screening and ultrasound.

When is the second ultrasound screening done during pregnancy?

The second ultrasound is done from 20 weeks of pregnancy to 24 weeks. This study is very important, because it helps to identify the condition of not only the fetus, but also the placenta. At these times, the image of the fetus can no longer fully fit on the monitor screen, so the specialist studies its individual parts, measuring the size of the head, the parameters of the femur, and the circumference of the mother's abdomen.

It is desirable to do ultrasound in a good clinic with experienced specialists. The size of the fetus may differ from the norm, but does not necessarily indicate a pathology. The doctor must be able to compare many factors. Usually, how many weeks of pregnancy have passed, indicate the size of the femur and head of the fetus. But these results also depend on genetics.

As for the circumference of the mother's abdomen, this size can also say a lot. If it is less than the norm set for a certain period, the doctor has the right to suspect a developmental delay. If more, then the fetus may simply be overweight.

Screening of the 2nd trimester, namely ultrasound, allows you to study the internal organs of the fetus in great detail, which was very difficult at the first screening.

During an ultrasound examination, the doctor evaluates not only the condition of the child, but also his surroundings. Its development largely depends on this, and the indicators of the placenta, uterus and amniotic fluid, which deviate from the norm, indicate the manifestations of various fetal pathologies.

For example, if a doctor finds a thickening of the placenta when examining it, it is possible that the cause is an intrauterine infection. A very important factor is the degree of maturity, which should depend on the age of the fetus. Until 27 weeks, the placenta should be normal grade zero. If she begins to age prematurely, then there is placental insufficiency, which negatively affects the development of the fetus. He may receive less nutrients, which means that his growth is inhibited.

In the second trimester, during the ultrasound examination, the doctor examines the placental location. When the placenta is lowered so low that it literally blocks the opening of the exit from the uterus, a presentation is placed. This is a rather dangerous situation when a pregnant woman must constantly limit herself in movement so as not to provoke a miscarriage.

Important for ultrasound analysis and amniotic fluid. The doctor evaluates their number. Oligohydramnios indicates a kidney disease of the fetus, and polyhydramnios indicates an infection that threatens the child. It is also indicated by the presence of various suspensions and flakes in the waters.

The second pregnancy screening allows you to examine the umbilical cord in detail using ultrasound. This is important to eliminate the risk of entanglement. However, if the head of the fetus is entwined once, it has plenty of time before delivery to unravel on its own.

It is very important to study the cervix, as it is also responsible for maintaining pregnancy. If there is isthmic-cervical insufficiency, then spontaneous abortion may occur. In other words, the cervix may open at the wrong time. A specialist can assess the condition of the cervix only with the help of ultrasound.

Also, the second screening during pregnancy is an opportunity not only to see the movements of the unborn baby, to determine his heartbeat, but also to listen to him, and also to see the features of the child's face. At this time, the doctor can almost unmistakably name the sex of the child.

The results of the second trimester ultrasound study are necessarily compared with the data of the previous study, which will give the doctor the opportunity to make a complete picture of the development of the fetus.

Of course, it is impossible to say that deviations from the norm will necessarily lead to the most serious diseases of the child, with a 100% guarantee. But in most cases of medical practice, this is what happens. However, blood tests can be interpreted differently, not only according to how many weeks the fetus is, but also according to other factors.

For example, with artificial insemination, a completely normal level of AFP and estriol will be completely normal, while chorionic gonadotropin, on the contrary, will be higher.

The levels of all hormones will be increased with obesity of the future woman in labor. They will also be increased during multiple pregnancy.

In addition to a biochemical blood test and an ultrasound examination, a woman can be referred for other examinations.

Chorionic biopsy is the sampling of chorion tissue. This analysis allows you to identify chromosomal pathologies and other gene diseases. Chorionic biopsy is performed through the vagina or abdominal cavity. Analysis can be done starting from the ninth week. It is usually prescribed to all women over 35 years of age, as well as to those who already have a child with malformations. The analysis is not always safe for the mother and fetus, as it can cause bleeding. But it is he who allows you to determine pathologies with great accuracy.

Another additional study is cordocentesis. It consists in obtaining blood from the umbilical cord. But it can only be produced starting from the 18th week. Cordocentesis is done by puncturing the abdominal wall, pumping out the required amount of blood from the umbilical cord.

Amniocentesis is the analysis of amniotic fluid, which is taken with a special syringe. The analysis can confirm or refute about two hundred fetal pathologies. But it is also unsafe to produce it. As complications, detachment of the fetal membrane, infection, and sometimes miscarriage are noted.

Main pathologies that can be found during the second screening

When the first screening is done, doctors, in accordance with the test results, can already suspect various pathologies. But the indicators they receive in the second trimester either confirm the fears or refute them. Parents are often not aware of the various deviations that may occur in the process of conception and child development. Most of them have been studied well, but the exact answer to the question of why complications arise has not yet been found.

The most common is Down syndrome. Everyone has heard about him. Its cause is an extra chromosome in the 21st chromosome row. Children with this pathology have a specific appearance, suffer from mental abnormalities and diseases of the internal organs. Often after birth, they live quite a bit.

In addition to Down syndrome, there are other trisomies - de Lange syndrome, Edwards syndrome, Patau syndrome. All of them are characterized by multiple malformations of the internal organs, a lag in physical and mental development, and a peculiar appearance of the fetus and child after birth.

For competent doctors, it is enough to simply establish defects using ultrasound data. For example, Patau's syndrome can be expressed in abnormal formation of the brain, in tachycardia and an enlarged bladder. If the fetus has a shortened nasal bone, this is talking about Down syndrome.

In addition to trisomies, malformations of the central nervous system are common. These include anencephaly, or the absence of hemispheres in the brain. A cephalocele is characterized by protrusion of the meninges through defective skull bones. Hydrocephalus is an anomaly in which the ventricles of the brain enlarge.

Often there are anomalies of facial structures, such as cleft palate and upper lip, malformations of the heart, genitourinary system, bones and gastrointestinal tract.

How many weeks should the fetus be to identify pathologies? This is usually best done at the first screening at 10-13 weeks. It is at this time that it is still possible to terminate the pregnancy if the results of the studies show the non-viability of the fetus in the future. But to make such a diagnosis, you need to conduct the maximum number of studies.

However, to terminate a pregnancy or continue it is a difficult question from an ethical point of view. Every mother has the right to decide for herself whether to trust the advice of doctors or not. But to make a decision, you should consult with the maximum number of different doctors.

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 🙂 During 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, thinking about the tactics of the conversation 🙂 From whining to threats 🙂 It worked! Which I am very glad about 🙂 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 🙂 I’m groovy, I decided to save my nerves, I don’t need such experiences ... Yes, and unnecessary tests not proving) 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.