Modern medicine provides the expectant mother with the opportunity to receive fairly complete information about the process of the formation of the baby.

At will or if necessary, a pregnant woman has the opportunity to undergo an examination that will help determine the absence of a threat to the normal and natural formation of the fetus.

One of these methods is prenatal screening, which literally translates as "prenatal screening".

In the CIS countries, the use of screening examinations began not so long ago; it is especially popular among pregnant women. This examination helps to identify risk groups in pregnant women and directly in the fetus.

Screening happens:

• ultrasound (performed using ultrasound);
• biochemical (a study of various blood markers is being carried out);
• combined (consists of ultrasound and blood tests).

The screening procedure consists of a blood test and ultrasound, as well as a questionnaire.

The questionnaire contains personal data that is necessary to determine the gestational age and calculate the risks of possible fetal defects. Analyzes are done based on the gestational age.

After that, all information received is processed by a computer program, which provides information about possible risks at the output.

It must be remembered that any result obtained in this case is not 100% reliable. Additional studies may be recommended to clarify these data for a pregnant woman.

Should I do a second screening?

As you know, there are certain factors that can cause the development of various pathologies in an unborn child. These factors include:

• the threat of pregnancy in its early stages;
• the impact on the mother's body of harmful professional and environmental factors;
• previously occurring spontaneous;
• the presence of viral infections in early pregnancy;
• the mother reaches the age of 35;
• alcoholism and drug addiction of parents;
• already existing child with congenital pathologies;
• various hereditary diseases of parents;
• the use of drugs in early pregnancy;
• conception of a child as a result of closely related ties.

All of these factors can be the cause of various pathologies of the unborn child.

Therefore, if a pregnant woman has encountered at least one of these factors, she needs to undergo a second screening examination.

The second screening allows you to identify the likelihood of developing diseases such as Down syndrome (trisomy on chromosome 21), Edwards syndrome (trisomy on chromosome 18), neural tube defects.

When to do the second screening?

As you know, the first screening study is done during the first trimester (-pregnancy), the second - during the second trimester (-pregnancy).

Norms and indicators

The second screening consists of an extended ultrasound and a biochemical blood test for the content of 3 hormones.

Advanced ultrasound includes examination of the entire fetus (general structure, condition of internal organs - brain, heart, spine), as well as the placenta and amniotic fluid. Based on the results, the date of birth is predicted.

Biochemical blood test sent to establish the level of 3 hormones such as AFP (alpha-fetoprotein), SE () and hCG ().

Alpha fetoprotein- a protein present in the blood of the fetus in the initial stages of development. Its main task is to protect the fetus from the maternal immune system, neutralize maternal sex hormones, and form the fetal liver.

Normally, the level of AFP (U / ml) at - pregnancy is 15-95, at 20- - 27-125.

Free estriol- one of the most important pregnancy hormones. Promotes the development of blood flow in the vessels of the uterus, determines the development of the ducts of the mammary glands in pregnant women.

The level of this hormone reflects the state of the placenta. In the normal development of pregnancy, the level of SE constantly increases from the moment the placenta is formed.

Chorionic gonadotropin is a hormone produced by the placenta. It contributes to the preservation and functioning of the corpus luteum. The maximum concentration of this hormone reaches a maximum at the 9th pregnancy.

The following levels of hCG (U / ml) are normal depending on the week of pregnancy: 16 weeks (10-58); 17– (8–57); 19 weeks (7–49); 20–(1.6–49).

Laboratories that perform biochemical analyzes of these hormones may differ from each other in the different reagents they use. In this case, the laboratory provides its own norms for the levels of these hormones.

If the values ​​are indicated in MoM (relative units), then for all indicators the normal level of indicators will be from 0.5 to 2.0 MoM.

Bad performance

Simple tests that help identify the main pathologies in the development of the fetus will be a signal to eliminate problems if they occur.

This is a guarantee that as a result a healthy baby will be born who will give only positive emotions to his parents.

All abnormal levels of the 3 main hormones during pregnancy, which are given above, are evidence of the possibility of developing various fetal pathologies:

1. Elevated levels of AFP may indicate the pathological development of the neural tube, the occurrence, improper formation of the food system, the formation of craniocerebral hernia, destruction of the fetal liver by viral infections.
2. Reduced AFP content - talk about the development of Down and Edwards syndrome, fetal death, incorrect determination of the timing of pregnancy.
3. Elevated values ​​of the SE level - to be the cause or development of a large fetus.
4. Reduced SE values ​​may be a fact of placental insufficiency, the existence of a threat, diseases of the adrenal glands of the fetus, developmental disorders of the brain, Down's syndrome, and intrauterine infections.
5. Elevated levels of hCG - indicate a multiple pregnancy, a discrepancy in the gestational age, development, the presence of the mother, Down's syndrome.
6. Reduced values ​​of hCG are manifested in the presence of a threat of abortion, placental insufficiency, fetal death.

In conclusion of this topic, it must be emphasized that it is desirable for every pregnant woman to undergo screening examinations both during the first and second trimesters.

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

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

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

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

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

Ultrasound screening and its norms

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

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

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

Table 1 - KTR norm according to gestational age

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

Too small size of the fetal body indicates:

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

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

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

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

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

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

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

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

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

Table 3 - Norms of TVP by weeks of pregnancy

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Standard ultrasound protocol in the first trimester

Biochemical screening ("double test") and its interpretation

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

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

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

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

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

A decrease in the value of beta-hCG indicates:

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

PAPP-A Plasma pregnancy-associated protein A.

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

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

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

An increase in PAPP-A can be observed if:

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

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

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

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

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

Ultrasound screening: norms and deviations

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

Table 7 - Normative dimensions of the fetus according to ultrasound

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Table 10 - Norms of the amniotic fluid index by week

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

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

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

With severe oligohydramnios, drug treatment must be prescribed.

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

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

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

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

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

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

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

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

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

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

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

Standard ultrasound protocol in the second trimester

Biochemical screening or "triple test"

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

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

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

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

Table 12 - The rate of free estriol by week

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

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

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

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

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

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

Table 13 - AFP norm by week of pregnancy

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

Third screening (at 30-34 weeks)

In total, two screenings are carried out during pregnancy: in the first and second trimesters. In the third trimester of pregnancy, they carry out, as it were, a final control over the state of health of the fetus, look at its position, evaluate the functionality of the placenta, and decide on the method of delivery.

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

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

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

Table 14 - Thickness of the placenta (normal)

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

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

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

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

The degree of maturity of the placenta (normal):

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

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

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

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

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

Preparing for a Screening Ultrasound

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

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

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

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

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

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

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

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

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

Preparation for biochemical screening

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

The cost of comprehensive screening

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

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

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

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

The second screening during pregnancy is carried out in order to identify congenital malformations and chromosomal pathologies that could not be detected at the 1st stage of the survey in the previous trimester. The complex of studies includes ultrasound and biochemical analysis of the blood of the expectant mother. How many weeks are 2nd trimester screenings? How to prepare for it, how to take it and what does it show?

Features of the second screening

During pregnancy, 3 screenings are performed - one in each trimester. If the blood counts in the initial trimester of pregnancy were normal, stage 2 usually consists only of a planned ultrasound. However, if a woman is at risk, she needs to undergo a second full screening. A pregnant woman is included in this category if:

• had problems bearing a child in previous pregnancies;
• had a severe infection during the current pregnancy;
• future parents are related by blood;
• the first screening revealed a high risk of congenital pathologies;
• age over 35;
• there is a long-term threat of miscarriage;
• used medications prohibited during gestation;
• the future mother and father, their older children have congenital diseases or malformations;
• neoplasms were found.

What is the duration?

The timing of the examination may vary from 16 to 24 weeks of pregnancy. There are some features here. The results of a blood test are considered the most accurate if the biomaterial was taken from 16 to 18 weeks. The timing of the passage of ultrasound according to the order of the Ministry of Health is from 18 to 21 weeks. Most often, in practice, the timing of the second screening is from 18 to 20 weeks. The exact date of the study is determined by the doctor leading the pregnancy.

What are they watching?

With the help of ultrasound of the 2nd trimester, which is more often done at a period of 20 weeks, the anatomical structure of the fetus is assessed for developmental anomalies and signs of hereditary diseases. The state and volume of the amniotic fluid, the fetal heartbeat, and its mobility are determined. They look at the parameters of the baby's body: the length of the bones of the upper and lower extremities, height, the size of the head and abdomen.

On ultrasound, the formation and location of the placenta, the number of vessels in it are determined. The doctor also evaluates the condition of the uterus, cervix and ovaries, the tone of the uterine walls.

The specialist checks the number of fingers, size, structure and maturity of the baby's organs. The structure of his facial bones, nose and hard palate is assessed.

Prescribed screening measures blood parameters such as alpha-fetoprotein (AFP) and human chorionic gonadotropin (hCG). AFP is a protein produced by the fetus. It transfers the necessary compounds to all organs and tissues of the baby, protects it from the maternal immune system, and neutralizes estrogens. HCG is produced by the membranes of the fetus. It stimulates the synthesis of other hormones glucocorticoids and progesterone, supports the functioning of the placenta.

How is the research done?

Ultrasound examination of the second trimester does not require special preparation, however, the day before the procedure, it is recommended to refrain from fried and fatty foods, chocolate, citrus fruits, cocoa. Blood is taken on an empty stomach, so it is better to prescribe an analysis in the morning. A couple of hours before the examination, it is recommended to refuse water. If the pregnant woman takes any medications, at the discretion of the doctor, their intake may be delayed.

For an ultrasound, the expectant mother lies on the couch and exposes her stomach. The procedure in the 2nd trimester is done transabdominally. A special gel is applied to the skin, acting as a conductor between the device and the body. The transducer sends out sound waves that bounce off the tissues and return back. The signals are converted and displayed on the monitor screen, where the image is rendered. The specialist moves the sensor along the abdomen, takes the necessary measurements and records the information received. The procedure takes from 15 to 25 minutes, the result is issued immediately.

Norms and interpretation of results

Table. The second planned ultrasound, norms:

Gestational age	Abdominal circumference	Head circumference	Fronto-occipital size, mm	Biparietal size (head width), mm	Forearm bone, mm	Femur, mm	Humerus, mm	Leg length, mm	nose bones	amniotic index
16	88–116	112–136	41–49	31–37	12–18	17–23	15–21	15–21	5,4–7,2	73–201
17	93–131	121–149	46–54	34–42	15–21	20–28	17–25	17–25		77–211
18	104–144	131–161	49–59	37–47	17–23	23–31	20–28	20–28	6,6–8,0	80–220
19	114–134	142–174	53–63	41–49	20–26	26–34	23–31	23–31		83–225
20	124-144	154–186	56–68	43–53	22–29	29–37	26–34	26–34	7,0–8,3	86–230
21	137–177	166–200	60–72	46–56	24–32	29–37	29–37	29–37		88–233

The second ultrasound helps to identify deviations of fetometric indicators. Too small sizes can indicate an incorrectly set period, developmental delay or hereditary diseases. The discrepancy between the length of the bones of the fetus to the norm may indicate genetic abnormalities, pathologies of the uterus, lack of progesterone, fading of the fetus.

The discrepancy between the size of the head and the norm, revealed on ultrasound at number 2, is associated with the risk of brain anomalies.

Hydrocephalus is characterized by the accumulation of an excessive amount of cerebrospinal fluid under its membranes, resulting in increased intracranial pressure. The prognosis depends on the characteristics of the pathology, its size and associated disorders.

Anencephaly is one of the most severe malformations of the brain; rarely, children with this diagnosis live more than a few days. It is a neural tube defect that disrupts the development of the structures of the skull, soft tissues, or cerebral hemispheres.

Biparietal size (the width of the head from temple to temple) also characterizes the development of the brain. If the value is too small, this indicates the underdevelopment of the organ or the absence of its structures. Exceeding the norm may indicate a hernia, hydrocephalus or neoplasm. Sometimes this happens when the fetus develops spasmodically.

The structure of the placenta must be homogeneous, otherwise a violation in its functioning is noted. A thickness less than the norm of 150 mm can lead to underdevelopment of the fetus. Normally, this organ has 3 vessels. Their smaller number may indicate genetic defects. A decrease in the amniotic index indicates oligohydramnios, an increase indicates polyhydramnios. Both conditions require further diagnosis and treatment. Shortening, softening or opening of the cervix indicates that there is a threat of miscarriage.

Table. Second screening, normal blood counts:

The second screening helps to identify abnormalities in blood counts that may indicate abnormalities in the course of pregnancy and fetal malformations. Decoding is carried out by a doctor, if suspicious results are detected, the test is repeated. If you wish, you can take a screening test 2 times in a row - it is absolutely safe.

The reasons for increased hCG can be: overweight of the expectant mother, gestational diabetes mellitus, artificial insemination, multiple pregnancy. On the part of the fetus, the deviation can be caused by defects and genetic abnormalities. The indicator is reduced if there is a threat of miscarriage and miscarriage, there is placental insufficiency or developmental delay.

An increase in alpha-fetoprotein indicates a multiple pregnancy or a malformation of the brain - anencephaly. Another pathology that causes such a deviation is a genetic anomaly of the spinal column, in most cases accompanied by impaired development of the spinal cord, more often in the form of a spinal hernia. A low rate may indicate chromosomal pathologies - Edwards or Down syndrome.

Why is a triple test needed in the 2nd trimester and how is it carried out?

A triple test is a set of studies that includes 3 analyzes. They also help assess the health of the baby. Such a test is prescribed in addition to the mandatory second ultrasound. In addition to hCG and AFP indicators, the level of free estriol is assessed - this is a hormone that is responsible for establishing a relationship between the mother and fetus. It is produced by the placenta, and later by the baby's liver. He takes part in the placental circulation, the production of progesterone, the preparation of the mammary glands for lactation.

For biochemical screening of the 2nd trimester, the biomaterial is taken from a vein, more often an ulnar vein. A tourniquet is applied 10 cm above the elbow. After that, the pregnant woman is asked to squeeze and unclench her fist several times to increase blood flow. The health worker determines the puncture site, disinfects and makes a fence. After that, a sterile napkin is applied. In order to stop bleeding and prevent bruising, the arm should be kept bent at the elbow for about 10 minutes. The analysis is performed using a computer, the result is prepared up to 14 days.

Normal results of estriol in the framework of the second screening (triple test) are given in the table:

High rates of free estriol are observed in multiple pregnancies and an increased level of oxytocin in the body of the expectant mother. Low values ​​may indicate complications: chromosomal pathologies, hypoxia, fetal fading, growth retardation, placental insufficiency. Possible causes of downward deviations are diabetes mellitus, liver disease and anemia.

Quadruple test - what is it and why is it carried out?

The quadruple test, which is also carried out as part of the second screening, includes the same blood tests as the triple, but one more indicator is added to them - inhibin A. This is a sex hormone that is always present in the body, but during pregnancy its level rises .

It is a marker of chromosomal pathologies (Down and Edwards syndromes), so its value is used to assess the risk of such congenital anomalies. The upper threshold value is 2 MoM, exceeding indicates a deviation. A low level of inhibin A occurs with habitual miscarriage or other disorders in the course of pregnancy.

How much does screening cost?

2nd trimester screening costs vary depending on where the study is being done. In public institutions, ultrasound can also be done free of charge, however, a biochemical test under such conditions is available only to pregnant women who are at risk. Commercial clinics set prices based on the quality of service, equipment and location (in large cities, the cost is usually higher).

The price is affected by the range of services to be done. Double screening (blood test) will cost less than triple or quadruple.

Biochemical screening, depending on the number of parameters evaluated, costs 1,000–2,000 rubles in Moscow. (data as of September 2018).

The cost of ultrasound diagnostics also varies. A conventional study with a black and white flat image is the most democratic option. With a three-dimensional ultrasound, the picture is of high quality, color and volume. You can see even the smallest features of the baby. A 4D study allows you to get a video recording, since the fourth dimension is time. The last two types of prenatal diagnostics are mainly found in private clinics, the price for them is quite high. The average cost of ultrasound for September 2018 in Moscow is 2500–3200 rubles.

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

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The essence of 2nd trimester screening

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

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

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

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

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

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

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

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

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

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

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

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

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

Structure 2 screening

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

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

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

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

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

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

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

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

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

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

Biochemical screening 2nd trimester

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

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

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

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

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

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

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

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

Screening preparation

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

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

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

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

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

When is the best time to do

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

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

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

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

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

Useful video: second screening during pregnancy

Conclusion

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

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The second screening during pregnancy is a comprehensive diagnosis, which includes both ultrasound and the determination of several marker hormones in the blood of the expectant mother.

It is performed for all women to confirm or refute the results of their first screening, as well as for acute indications for screening ultrasound during pregnancy.

There are nuances of preparation for the study.

Data decoding is carried out according to the same principle as in the screening of the first trimester.

Should pregnant women undergo a second screening?

The study is carried out according to the same indications as in the first trimester:

1. future parents are relatives
2. there has been an acute bacterial or viral disease
3. the mother suffers from one (several) of those diseases that can be genetically transmitted: diabetes mellitus, diseases of the musculoskeletal system, oncopathology
4. one of the future parents has a genetic (chromosomal) disease in the family
5. had a miscarriage or spontaneous preterm birth in this woman
6. one or more children with developmental anomalies have already been born
7. had a history of fetal death before delivery.

2nd trimester screening will also be ordered if:

1. the first ultrasound of pregnant women, which was done at 14 weeks and later (for various reasons), revealed a pathology of fetal development (if this study was earlier, the woman is sent for screening of the 1st trimester)
2. in the period of 14-20 weeks, an acute infectious disease developed
3. the woman was diagnosed with a tumor later than 14 weeks of her pregnancy.

In the latter cases, the pregnant woman is referred to a geneticist, who decides whether to carry out a complete perinatal examination of the 2nd trimester.

There may be situations when it will be sufficient to conduct a second ultrasound examination in the conditions of the perinatal center (that is, biochemical screening will not be carried out).

What is seen on ultrasound in the second trimester

What is looked at in the 2nd screening study? When conducting a diagnostic ultrasound of the 2nd trimester, the doctor evaluates:

• the lengths of the bones of the same name on both sides, the volumes of the head, chest, abdomen - the second ultrasound screening allows us to conclude that the development is proportional and consistent with the gestational age
• ventricles and cerebellum
• spine
• facial structures in front and profile (especially with 2 screening ultrasound during pregnancy, the nasolabial triangle and eye sockets are examined)
• ventricles, atria of the heart, places of origin of large vessels from it (diagnosis of the 2nd trimester shows if there are any abnormalities in the development of the cardiovascular system)
• kidneys and bladder
• stomach and intestines.

What does the second prenatal examination by maternal and temporary (provisional) organs show:

1. location of the placenta
2. placenta thickness
3. structure and maturity of the placenta
4. the number of vessels in the umbilical cord
5. amount of amniotic fluid
6. condition of the cervix and walls of the uterus
7. condition of the uterine appendages.

Based on the second screening ultrasound during pregnancy, it is concluded whether there are fetal malformations or not.

How to prepare for the second perinatal diagnosis

The second screening during pregnancy consists of two stages:

• diagnostic ultrasound (according to the sensations and nature of the conduct, it does not differ from the usual examination during pregnancy)
• screening test: this word refers to the analysis of venous blood for a certain amount of hormones.

It is no longer necessary to prepare for an ultrasound examination at this time: the intestines, no matter how many gases there are, are pushed back by the pregnant uterus. And the full bladder, which served as a window for the ultrasound, has now been replaced by amniotic fluid.

Before donating blood at the 2nd screening during pregnancy, preparation is needed: during the previous day, you deny yourself the following products:

• chocolate
• cocoa
• citrus
• seafood
• fatty and fried foods.

In addition, before you donate blood, you need at least 4-6 hours without eating at all. You can only drink water for 4 hours, but without gas and in an amount of not more than 150 ml.

3rd trimester screening does not require any preparation at all.

When does this study take place?

Timing of diagnosis 2 trimesters: from 16 to 20 weeks. This is very important for a blood test for the level of hormones in it. The timing of ultrasound screening of the 2nd trimester completely coincides with a biochemical blood test: ultrasound diagnostics is done first, with its result people go to donate blood. When is the best time to do the second test? 2 screening is best done at 17 weeks gestation or one week earlier.

Read also:

Ultrasound examination of pregnancy at 13-14 weeks

How the study is done

The study of pregnant women consists of the following manipulations:

1. Ultrasound diagnostics during pregnancy. This procedure in the second trimester of pregnancy is carried out only transabdominally, that is, through the skin of the abdomen. To do this, you simply lie down on the couch, open your stomach, and the doctor will drive the sensor along its front wall. It does not cause pain or discomfort.
2. Biochemical screening 2nd trimester. You come on an empty stomach to the laboratory that conducts this study, they take a few milliliters of blood from a vein. There you provide the results of ultrasound diagnostics, fill out personal data.

So they do the diagnosis of the 2nd trimester. The received indicators will be processed by the program - you can pick up the results only after 2 weeks.

Deciphering the results

2 screening during pregnancy consists of several indicators, each of which has its own norm.

Biochemical diagnostics

The indicators of the second screening, its biochemical part, are hormone levels:

• human chorionic gonadotropin (hCG)
• estriol (E3)
• α-fetoprotein (AFP)
• and in the event that not a triple, but a quadruple test is carried out, the level of inhibin.

The results of the second study normally depend on the duration of pregnancy. Norms of diagnostics of the second trimester:

Term, weeks	HCG level, honey / ml	AFP, U/ml	E3, nmol/l
16	10-58 thousand	15-95	5,4-21
17	8-57 thousand	same	6,6-25
18	8-57 thousand	same	6,6-25
19	7-49 thousand	15-95	7,5-28
20	1.6-49 thousand	27-125	7,5-28

The indicators of the second examination during pregnancy are evaluated by the MoM value - the average value, which is calculated taking into account the age, body weight and the region where the pregnant woman lives. The screening score of a given woman is divided by the value obtained from studies in a large sample of women of the same age living in the same area.

Examination data of the 2nd trimester is deciphered as follows:

• if the hormone is in the range of 0.5-2.5 MoM, this is considered normal
• if the results of the second “sifting” during pregnancy show a figure less than the lower limit (0.5) or higher than 2.5, this requires additional consultation with a geneticist.

Deciphering the diagnosis of the second trimester is to determine the degree of risk for a particular pathology (it is written as a fraction).

Norm - if the risk is less than 1:380(for example, 1:500 or 1:1000). A high risk is considered to be 1:250-1:360 for any pathology (the calculation is for Down syndrome, neural tube defect, Edwards, Patau). In this case, a consultation with a geneticist is required.

At a risk of 1:100, you may be offered an invasive diagnosis, that is, confirmation of the alleged anomaly by obtaining the chromosome set of the fetus itself.

Indicators of ultrasound diagnostics

2 pregnancy screening evaluates:

• indicators of fetometry (measurement of the size of the fetus)
• the structure of the face is assessed: there should be a normal size of the nasal bone, there should not be a cleft of the face, both eyeballs should be normally developed
• structure of internal organs: heart, brain, spine, stomach and intestines, lungs, bladder and kidneys
• lung maturity
• attention is drawn to the number of fingers on each limb
• amount of amniotic fluid
• thickness and maturity of the placenta
• the condition of the cervix and body of the uterus is examined
• attention is drawn to the uterine appendages.

Based on a visual assessment of the external and internal organs of the fetus, the correspondence of the size of the fetus to its gestational age, the results of an ultrasound examination of the 2nd trimester are issued: does the baby correspond to its term, does it have developmental anomalies.

Normal readings for some weeks

11 week

Screening at week 11 is still included in the concept of the first, and not the second examination during pregnancy.

• HCG \u003d 20-90 thousand honey / ml
• PAPP = 0.45-3.73 mU/ml
• KTR on average - 43 mm
• BPD average - 17 mm
• collar zone 0.8-2.4 mm
• the bones of the nose should already be there, but its size is not determined.

13 week

Diagnosis at 13 weeks of gestation also applies to the diagnosis of the first trimester. His rules:

• HCG \u003d 15-60 thousand honey / ml
• PAPP = 1.03-6.0 mU/ml
• nasal bone - 3 mm
• KTP - 51-87 mm
• collar area thickness = 0.7-2.7 mm
• BPD = 26 mm.

14 week

Screening at 14 weeks pregnant is a routine ultrasound. Blood is not taken at this time. Research norms:

• BPR = 27-29 mm
• nasal bone: 3.4-3.6 mm
• KTP = 76 mm
• head circumference (OG) - 95-106 mm
• girth of the abdomen -78 mm
• thigh: 12-15mm
• shoulder: 13 mm.

16 week

Examination at 16 weeks of gestation. This is the first week of the second stage of prenatal diagnosis. Norms of "sifting" the second trimester of pregnancy for this week:

• HCG \u003d 10-58 thousand mU / ml
• ɑFP = 15-95 U/ml
• E3 = 5.4-21 nmol/l
• BDP = 31-37 (35 - on average) mm
• LZR = 41-49 mm
• OG = 112-136
• coolant = 88-116 mm
• thigh:17-23mm
• shoulder: 15-21
• forearm: 12-18
• drumstick: 15-21 mm
• amniotic water index (IAI): 80-200 mm.

20 week

Screening at the 20th week of pregnancy is normally represented by the following indicators:

• HCG \u003d 1.6-49 thousand honey / ml
• ɑFP = 27-125 U/ml
• E3 \u003d 7.8-28 nmol / l
• BDP = 43-53
• LZR = 56-68
• belly: 124-164 mm
• head circumference: 154-186
• thigh: 29-37
• shoulder length: 26-34
• forearm: 22-29
• drumstick: 26-34
• placenta thickness: 16.7-28.6mm
• placental maturity - "0"
• IAI \u003d 93-130mm.

Screening at 20 weeks is the last time you can still determine hormones in the blood. If you had an indication, but you didn’t, you can only rely on ultrasound, and later on cardiocurrent and dopplerography, to make sure that the fetus is alive.

22 week

Screening at 22 weeks of gestation consists only of ultrasound diagnostics. Hormones in this period are no longer determined. If malformations that are incompatible with life or cause significant disability are identified, this period is the deadline for making a final decision on prolonging the pregnancy. This is so because after 23 weeks, medical termination of pregnancy will be called preterm birth.

Normal readings this week (in millimeters):

• nasal bones - 5.8-6.1 each
• BDP = 48-60
• OG = 178-212
• coolant = 148-190
• hip: 35-43
• lower leg: 31-39
• forearm: 26-34
• shoulder: 31-39.

Answers to the most common questions about the study

AT.:Is it true that the second set of diagnostics during pregnancy was canceled?

O.: According to the Order of the Ministry of Health of the Russian Federation dated November 1, 2012 N 572n, with normal indicators of the first biochemical study, screening of the 2nd trimester is carried out only as an ultrasound scan in a perinatal center.

This is necessary in order to exclude late-appearing anomalies in the development of the fetus. That is, if the PAPP and hCG levels in the first trimester were normal, the risk is above 1:380, then 2nd screening during pregnancy is performed only as an ultrasound diagnosis.

If a high risk (1:100 or more) was detected in the first trimester, a woman must be consulted by geneticists. If necessary, she undergoes invasive diagnostics, or the question of the advisability of conducting a full screening study of the II trimester before such a study is decided.

AT.:Increased hCG at the second screening. What does this mean?

O.: It can be under such conditions:

1. multiple pregnancy
2. toxicosis
3. diabetes
4. down syndrome
5. incorrectly calculated gestational age.

AT.:What is a bad 2nd trimester result?

O.: This means that in this case there is a high risk that a particular child may have Down syndrome or other pathology at the chromosomal level. Look at the form, in which pathology the “badness” is suspected. This is determined by the column in which the number 1:380 or less is written (for example, this entry applies only to Edwards syndrome).

AT.:How is it that the first screening is good and the second is bad?

O.: There can be 2 answers to this question:

1. there are defects that appear later, that is, closer to the second trimester (the period of 16-20 weeks was chosen precisely because of them)
2. the accuracy of the results of the 2nd screening is lower than in the first such study.

AT.:What if a bad second screening?

O.: Seek genetic counseling.