What is screening and how is it done? What does screening mean.

With the onset of pregnancy, a woman begins to worry about many questions. Every expectant mother wishes her baby a normal formation and development. In the early stages, there may be risks of developing certain diseases of the embryo. To study the condition of the baby, doctors prescribe screening for the 1st trimester. Norms for ultrasound (a photo of the examination is usually attached) a woman can find out from a specialist who observes her.

What is perinatal screening?

Perinatal screening involves a study of a pregnant woman, which allows to identify various malformations of the child at the stage of intrauterine development. This method includes two types of examination: a biochemical blood test and an ultrasound examination.

The optimal period for conducting such an examination has been determined - this is a period from ten weeks and six days to thirteen weeks and six days. There is a certain norm for screening ultrasound of the 1st trimester, with which the results of the examination of a pregnant woman are compared. The main task of ultrasound at this time is to identify serious and identify markers of chromosomal abnormalities.

The main anomalies are:

the size of the TVP - the thickness of the space of the collar zone;
underdevelopment or absence of the bones of the nose.

Ultrasound during pregnancy reveals signs of a disease such as Down syndrome, and some other pathologies of fetal development. The screening norm (ultrasound) of the 1st trimester should be analyzed up to 14 weeks. After this period, many indicators are no longer informative.

Screening of the 1st trimester: norms for ultrasound (table)

To make it easier for the doctor to determine the condition of a pregnant woman, there are certain tables of indicators of the development of the baby's organs. The ultrasound protocol itself is structured so that the dynamics of the formation and growth of the embryo is clear. The article presents the norms of screening of the 1st trimester.

Deciphering the ultrasound (table below) will help you get information about whether everything is in order with the fetus.

Embryo Viability Determination

To assess the viability of the embryo, it is very important to look at the heartbeat in the early stages. In a small person, the heart begins to beat as early as the fifth week of being in the mother's womb, and it can be detected using screening of the 1st trimester (ultrasound norms) already from seven weeks of fetal life. If at this time the heartbeat is not detected, we can talk about the probability (missed pregnancy).

To assess the viability of the embryo, the heart rate is also taken into account, which is normal for a period of six weeks from 90 to one hundred and ten beats per minute. These important indicators of 1st trimester screening, ultrasound norms, together with the study of blood flow and body length, should correspond to the reference data for gestational age.

The more modern equipment is used for examination, the better you can see all the organs and get the most accurate results. If there is a high probability of congenital malformations or genetic anomalies, then the pregnant woman is sent for a deeper examination.

In some regions, when registering in antenatal clinics, screening of the 1st trimester is mandatory for all pregnant women. Ultrasound standards may not coincide with the results obtained, so doctors immediately take the necessary measures to save the life and health of the child or mother. But most often, pregnant women who are at risk are sent for such an examination: these are women from thirty-five years old, those who have genetic diseases in the family and have previously born children, had miscarriages in previous pregnancies, stillborn children or non-developing pregnancies. Close attention is also paid to expectant mothers who have had viral diseases at the beginning of pregnancy, are taking dangerous medications or are under the influence of radiation.

If a woman has spotting in the first trimester, then ultrasound makes it possible to determine the degree of viability of the child or his death.

Terms of pregnancy

Conducting an additional examination to determine the exact duration of the state of pregnancy is indicated for women who have an irregular menstrual cycle or do not even know the approximate date of conception of a child. For this, in most cases, screening of the 1st trimester is used. Ultrasound standards, decoding of the main indicators and the date of conception do not require special medical knowledge. The woman herself can see the expected date of birth, the gestational age and the number of embryos. Basically, the number of weeks determined by ultrasound corresponds to the period that is calculated from the first day of the female cycle.

When conducting a study, the doctor makes control measurements of the size of the embryo. With the data obtained, the specialist compares the screening norms of the 1st trimester. Ultrasound is decoded according to the following parameters:

measurement of the distance between the sacrum and the crown of the embryo (7-13 weeks), which makes it possible to determine the actual gestational age using special tables;
measuring the length of the head of the unborn child (after 13 weeks), this is an important indicator in the second half of pregnancy;
determining the size of the longest - the femur of the body of the embryo, its indicators reflect the growth of the child in length (at week 14), in the early stages it should be approximately 1.5 cm, and by the end of bearing the child increase to 7.8 cm;
measuring the circumference of the abdomen in a child - indicates the size of the embryo and its estimated weight;
determination of the circumference of the head of a ripening fetus, which is also used to predict the natural birth of a child. Such a measurement is carried out even in the last stages of pregnancy, according to which the doctor looks at the size of the small pelvis of the future woman in labor and the head of the child. If the head circumference exceeds the parameters of the pelvis, then this is a direct indication for a caesarean section.

Definition of malformations

With the help of ultrasound in the first weeks of pregnancy, various problems in the development of the child and the possibility of curing him before birth are revealed. For this, an additional consultation of a geneticist is appointed, who compares the indicators obtained during the examination and the screening norms of the 1st trimester.

The decoding of ultrasound may indicate the presence of any malformations of the child, but the final conclusion is given only after a biochemical study.

1st trimester screening, ultrasound norms: nasal bone

In an embryo with chromosomal abnormalities, ossification occurs later than in a healthy one. This can be seen as early as 11 weeks when the 1st trimester screening is done. The norms for ultrasound, the decoding of which will show if there are deviations in the development of the nasal bone, help the specialist determine its size starting from 12 weeks.

If the length of this bone does not correspond to the gestational age, but all other indicators are in order, then there is no reason to worry. Most likely, these are the individual characteristics of the embryo.

The value of the coccyx-parietal size

An important indicator of the development of a little man at this stage of pregnancy is the size from the coccyx to the crown of the head. If a woman had irregular menstruation, this indicator determines the gestational age. The norm for screening ultrasound of the 1st trimester of this indicator is from 3.3 to 7.3 cm for a period of ten to twelve weeks inclusive.

The thickness of the space of the collar zone (TVP)

This indicator is also called the thickness of the neck fold. It is noticed that if the TVP of the embryo is thicker than 3 mm, then there is a risk of Down syndrome in the child. The values used by the doctor are shown by screening of the 1st trimester. Ultrasound standards (collar space thickness) are considered very important for further monitoring of a pregnant woman.

Determining the location of the placenta

A child's place (placenta) is necessary for the intrauterine blood supply of a small person. It is necessary to provide him with food. Ultrasound makes it possible to determine the anomalies in the development and position of the placenta. If it is located too low relative to the fundus of the uterus, this is called placenta previa, which can lead to blocking the exit for the baby during childbirth.

It is good to show the location of the child's place with ultrasound screening of the 1st trimester. The norms of such a study reject low placenta previa. But even if it is located close to the bottom of the uterus, doctors are in no hurry to sound the alarm, as it can rise over the course of pregnancy. But if the position of the placenta has not changed in the later stages, then the following problems are possible:

the placenta can obscure the cervix and prevent natural childbirth;
since the lower part of the uterus is stretched, the placenta can exfoliate from it and cause severe bleeding (placental abruption).

Examination of the yolk sac

On the 15-16th day of pregnancy from the day of conception, the process of formation is underway. This "temporary organ" of the baby is examined by doing an ultrasound scan (screening of the 1st trimester). Terms and norms for must show its presence and size. If it has an irregular shape, is enlarged or reduced, then the fetus may have frozen.

The yolk sac is an appendage located on the ventral side of the embryo. It contains a supply of yolk, which is necessary for the normal development of the baby. Therefore, it is very important to check what the norm for screening ultrasound of the 1st trimester in comparison with the parameters of the study is for monitoring the course of pregnancy. Indeed, at first (until the child's organs function independently), this appendage performs the function of the liver, spleen, and is also used as a supplier of primary germ cells that are actively involved in the formation of immunity and in metabolic processes.

The role of a biochemical blood test

Examining the state of the embryo, the doctor looks not only at the results of ultrasound (screening of the 1st trimester). The norms in it are as important as in the blood test. Such an analysis, in addition to an ultrasound examination, is carried out to determine at what level specific proteins (placental) are located. The first screening is done in the form of a double test - to detect the level of 2 protein species:

"PAPP-A" - the so-called pregnancy-associated plasma protein A.
"HCG" - free

If the levels of these proteins are changed, then this indicates the possible presence of various chromosomal and non-chromosomal disorders. But the identification of an increased risk does not mean that there is definitely something wrong with the embryo. Such results of screening of the 1st trimester, decoding, the norm of ultrasound indicate that it is necessary to more closely monitor the course of pregnancy. Often, a repeat study no longer shows the risk of genetic diseases.

16.07.2017 18

Medicine is improving every year. A few decades ago, for a pregnant woman, the mystery remained until the moment of the birth itself. Now it has become possible not only to find out the sex of the child, but also to find out about the possibility of his congenital diseases.

Prenatal means "prenatal", that is, during pregnancy. Screening literally translates as "sifting". In simple terms, the procedure eliminates cases with a high risk of birth defects.

If one is found, then this is the basis for termination of pregnancy. However, the final decision always remains with the woman.

What's happening?

You can, of course, do without it, but you should know that it allows you to get more accurate results. They, in turn, will help the doctor with a high probability to make or refute any diagnosis.

Ultrasound in the 1st trimester can be performed by two methods: abdominal and vaginal.

It should be noted that the baby is growing daily. Therefore, the indicators obtained at 10 and 14 weeks will be very different. You should not compare your values with the measurements of a friend or neighbor. Better pay attention to the rules:

at the beginning of the 10th week, the CTE is 3-4 mm, and at the beginning of the next - 5 mm;
at week 11, this figure should be in the range from 4.2 to 5.8 mm;
exactly at 12 weeks, the CTE varies in different women from 5 to 6 mm, and at 13 weeks it can reach 7.5 mm.

Collar zone

Always considered. It is he who can point out deviations and make the doctor suspect congenital pathologies. The following values indicate the absence of chromosomal abnormalities:

at 10 weeks TVP from 1.5 to 2.2 mm;
at 11 weeks - up to 2.4 mm;
at 12 weeks, the value is from 1.6 to 2.5 mm;
and at week 13 it is 1.7–2.7 mm.

nasal bone

If during the screening of the 1st trimester it turns out that there is no nasal bone, then this may be one of the signs of Down syndrome. This indicator is the second most important after the TVP.
· At 10-11 weeks' gestation, the nasal bone is normally detectable but not yet measurable. In this case, the sonologist simply indicates the presence of this indicator.
At 12 weeks and later, the nasal bone has a size of 3 mm. Therefore, this period is most often chosen for ultrasound of the first trimester of pregnancies.

The work of the heart

Determines the state of this important organ. It also changes over time. Here are the main rules:

10 weeks - 161-180 bpm;
11 weeks - 152-178 bpm;
12 weeks - 149-173 beats / min;
13 weeks - 146-170 beats / min.

Decryption

If at least one indicator of ultrasound diagnostics does not correspond to normal parameters, then the doctor will prescribe an additional examination. Its appearance depends entirely on what result was obtained initially.

For example, if the size of the fetus does not match, but the blood counts are good and there are no deviations in the TVP, an additional ultrasound is prescribed. There is a possibility that the first study was conducted with an error. If congenital anomalies are suspected (corresponding blood values and deviations from the norms of the nasal bone and TVP), then an amniocentesis may be offered to the woman.

It is important to be aware of the consequences of taking amniotic fluid, which can be very deplorable. Also, the gynecologist can prescribe, for which certain terms and norms are also established.

How right? If you do not have a medical education, then you will not be able to independently evaluate the information received. To do this, you should contact a gynecologist or reproductive specialist.

Based on ultrasound diagnostics and blood counts, a fractional value is compiled, which shows the risk of deviations. If it is minimal or tends to zero, then you will see the word "negative".

When the risk is higher, numerical fractions are put, for example, 1:370, which may mean Down syndrome in a child. A poor result and a high risk are reported by values in the range from 1:250 to 1:380.

Additionally

It is important to know that screening values can be affected by several factors. When evaluating the result and decoding, the doctor must take into account those.

When blood counts can be changed. At the same time, according to ultrasound, everything fits within the normal range.
Excess or deficiency of body weight leads to a shift in the value of hormones in the appropriate direction. Ultrasound signs remain normal.
Multiple pregnancy rarely acquires standard blood counts. On ultrasound in babies, the values \u200b\u200bremain normal, but may be underestimated.
In women after 35 years, the risk may be overestimated due to individual characteristics.

What does it say about Down syndrome?

The fetus is missing a nasal bone or cannot be measured after 12 weeks.
The facial contours are smoothed out more than in other children (can only be detected with the help of modern equipment.
Pathological blood flow in the duct, detected by dopplerometry.

How to recognize Edwards syndrome?

The fetal heart has a slow rhythm, reduced heart rate.
A hernia is found in the umbilical cord.
The nasal bones are not visualized at any time.
The umbilical cord has only one artery instead of two.
Indicators of Patau Syndrome
Unusually fast heartbeat.
Are present.
The growth of the embryo is impaired, small bones are noted.
Hernia in the region of the umbilical cord.

Let's summarize

Screening in the first trimester is very important for assessing the condition of the fetus. Some pathologies that are now established can be corrected already during pregnancy.

To detect them, they do an ultrasound. Other abnormalities require medical intervention immediately after childbirth (for example, heart disease).

There are anomalies that are incompatible with life or promise the birth of a disabled child. In such situations, a woman will have to make an important decision about whether to continue the pregnancy or terminate it.

We must not forget that there is a risk of errors, although it is small. Be sure to double-check the indicators if they turned out to be inconsistent with the standards.

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

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

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

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

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

Ultrasound screening and its norms

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

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

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

Table 1 - KTR norm according to gestational age

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

Too small size of the fetal body indicates:

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

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

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

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

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

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

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

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

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

Table 3 - Norms of TVP by weeks of pregnancy

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Standard ultrasound protocol in the first trimester

Biochemical screening ("double test") and its interpretation

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

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

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

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

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

A decrease in the value of beta-hCG indicates:

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

PAPP-A Plasma pregnancy-associated protein A.

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

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

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

An increase in PAPP-A can be observed if:

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

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

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

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

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

Ultrasound screening: norms and deviations

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

Table 7 - Normative dimensions of the fetus according to ultrasound

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

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

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

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

Table 9 - Normative values of the fetal cerebellum by week

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Table 10 - Norms of the amniotic fluid index by week

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

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

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

With severe oligohydramnios, drug treatment must be prescribed.

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

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

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

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

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

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

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

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

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

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

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

Standard ultrasound protocol in the second trimester

Biochemical screening or "triple test"

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

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

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

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

Table 12 - The rate of free estriol by week

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

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

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

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

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

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

Table 13 - AFP norm by week of pregnancy

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

Third screening (at 30-34 weeks)

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

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

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

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

Table 14 - Thickness of the placenta (normal)

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

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

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

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

The degree of maturity of the placenta (normal):

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

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

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

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

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

Preparing for a Screening Ultrasound

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

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

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

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

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

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

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

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

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

Preparation for biochemical screening

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

The cost of comprehensive screening

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

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

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

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

If a woman did not conduct an ultrasound examination of the fetus at an earlier date, then ultrasound at the 12th week of pregnancy becomes the first and takes on special significance.

The term already allows the mother to see the baby in its entirety, albeit for the time being on the equipment monitor. And the doctor has the opportunity to assess the anatomical features of the fetus and tell the expectant mother about them. From a medical point of view, ultrasound screening for 12 weeks (1 trimester) is of considerable value for determining measures for the further management of pregnancy and maintaining the health of the baby.

There are several reasons why an ultrasound examination of a pregnant woman at 12 weeks is of great importance:

At this time, the age of the unborn child can be determined with high accuracy, and later he will gain weight, and the error in the date of conception will be significant (up to a week).
At that time it is important to determine the size of the collar zone(this is the name of the soft tissues of the back of the head and neck). This indicator is key in the early diagnosis of chromosomal diseases, including Down, Patau, Edwards syndromes. Examination must be completed before 12 weeks, because after 14 weeks it will no longer be possible to detect chromosomal pathologies and some fetal malformations too.
The assessment of the placenta attachment site, the presence of detachment, the quality and quantity of amniotic fluid are significant indicators of pregnancy that affect the health of the child and the management of pregnancy - it is also important to find out at 12 weeks.
The doctor assesses the condition of the uterus - there should be no increased tone (that is, tension) or isthmic-cervical insufficiency. All these conditions require timely prescribed treatment, so high-quality and timely diagnosis during pregnancy plays a key role.

How does the baby develop?

Modern ultrasound allows the expectant mother to observe what is happening on the screen of the ultrasound machine along with the doctor. And the first examination becomes the first meeting of the mother with her son (or daughter).

Reference! Although it is still difficult to see a child in the usual sense on the monitor, women are anxiously waiting for this moment.

The most important thing at this stage is to make sure that everything goes as it should. And, of course, when the doctor says: “Listen to the beating heart of the child. Here is the head, here are the legs, but the arms, all the fingers have already formed. Everything is fine with you”, – mother is experiencing a surge of happiness.

By 12 weeks of pregnancy, all the organs of the child and the systems of his body are fully formed.

Reference! The weight of the baby now is no more than 19 grams, and the length of the body is about 9 cm.

Despite the tiny parameters, the brain of a child is no different from the brain of an adult except for its size.

Often, on an ultrasound, a woman sees how the baby sucks her finger, and his nails are already formed. The chaotic movements of the crumbs are thought out by nature - during them he trains his muscular apparatus.

Video

The ultrasound video below contains footage of the activity of the baby in the womb at 12 weeks of gestation.

What will the study show?

What is an ultrasound at the 12th week of pregnancy in terms of information content, and what is seen with it? Ultrasound screening at 12 weeks of gestation allows the doctor to see and evaluate:

dimensions of the unborn baby (the length of certain bones, body length and head parameters are fixed);
symmetry of the cerebral hemispheres;
the location of the kidneys, stomach, heart and other important organs;
possible developmental abnormalities, including heart defects, tumors, congenital anomalies;
signs of genetic disorders;
the place of fixation of the placenta (normally, it should be located on the anterior or posterior walls of the uterus);
the condition of the umbilical cord, the presence and functioning of 2 arteries and veins in it;
the length of the cervix, which depends on the duration of pregnancy and the individual characteristics of the expectant mother;
the exact date from the conception of the child.

How is it done?

The ultrasound examination procedure is performed transvaginally (by inserting a vaginal probe) or transabdominally (through the wall of the abdomen).

And if the first method is common only at the beginning of pregnancy, when it is still difficult to obtain the necessary information through the abdominal wall, then the second method is more widely used.

However, there are indications for transvaginal ultrasound at a later date.

The study is carried out transvaginally, if:

diagnosed with a low position of the placenta or chorion;
identified isthmic-cervical insufficiency, the severity of which must be assessed;
there are myomatous nodes;
there are suspicions of inflammatory processes in cysts or appendages;
there is a large layer of adipose tissue on the abdomen, through which it is not possible to see the necessary parameters.

Training

Preparation for the procedure depends on its type:

With transvaginal ultrasound, it is worth drinking 500 ml. water immediately before the study.
During transabdominal examination, increased gas formation should be avoided. To do this, on the eve of the study, it is not recommended to eat foods that cause fermentation (raw cabbage, grapes, white bread, legumes). You can take medications containing simethicone to help clear up the buildup of gas.

Who is assigned?

In our country, a three-time mandatory examination of all expectant mothers is regulated. It is carried out with a preventive purpose and is called screening. A screening study makes it possible to detect perinatal pathology early, even in those pregnant women who are not worried about anything.

There are three such studies in total, they are prescribed at different stages of pregnancy and include ultrasound and determination of the biochemical composition of the blood. So an ultrasound at week 12 is shown to all pregnant women, without exception.

Will a woman find out the gender of her baby at 12 weeks?

It happens that already at the first screening, the mother finds out who is worth waiting for - a boy or a girl. The genital organs of the child are already fully formed, but only a very experienced diagnostician will be able to discern the sex of the baby. It often happens that the baby turns sideways or back and does not want to open up to the doctor. Do not worry if the first ultrasound did not clarify the gender of the unborn child - it will be determined at the next examination.

Doctors of functional diagnostics have their own secrets of early recognition of the sex of the baby, because this information is very important for the mother. For example, when the child is located facing the sensor, the specialist can measure the angle formed by the back of the baby and the genital tubercle. If it is less than 30 degrees, it is likely that there will be a girl. An angle above the specified value indicates the expectation of a boy.

What is KTR?

One of the central indicators determined by ultrasound at 12 weeks is the coccyx-parietal size of the embryo. During the first screening, it should normally be about 5.1-5.3 cm, fluctuations of a few tenths of a centimeter are acceptable. The doctor will clarify that the size of the CTE is highly dependent on the exact gestational age. For example, at 11 weeks, the CTE indicator will be approximately 4.2 cm (allowable figures are from 3.4 to 5.0 cm).

The coccygeal-parietal size is a key factor in the highly accurate determination of the gestational age, but only for a period of 7 to 16 weeks.

Important! Determining the gestational age by KTR is unique in that the error when using this method is no more than 3 days.

But after 16 weeks, the method loses its relevance and completely different parameters come to the fore.

The resulting indicators must comply with the norm, which is determined by a special table. Based on a comparison of the two indicators, the doctor draws conclusions about the well-being of the embryo and the compliance of its development with the established deadline.

3D and 4D ultrasound - volumetric images for memory

More and more expectant mothers today prefer to replace conventional echography with 3D or 4D ultrasound. To what extent are these methods better than traditional research? How do they differ from each other and what do future parents give?

3D ultrasound allows you to get a three-dimensional picture (photo) on which you can accurately see the baby's face and see the details of his appearance, find out the gender of the child and count the tiny fingers. The difference between a 3D study and a traditional procedure is that it can be carried out only at certain times - from 20 to 33 weeks, and it is done only at the request of the parents, since from a medical point of view it is no different from a conventional ultrasound, but it costs several times more. once.

4D differs from 3D only in the ability to see how the baby lives in the uterus in real time. Three-dimensional ultrasound shows only static frames, but four-dimensional, thanks to the rotation of the picture, allows you to see the movements of the baby and his facial expressions.

Where to do it and how much does it cost?

Ultrasound at 12 weeks has no contraindications. As a rule, the doctor prescribes a planned procedure at a polyclinic at the place of residence or a large (regional) perinatal center, or a regional hospital with rich experience in examining pregnant women. Scheduled screening is free, but if parents want to see the image of the baby in volume or in real time, they will have to pay from 2,500 rubles. for 3D ultrasound and about 4,000 rubles for a 4D procedure.

Conclusion

All ultrasound examinations during pregnancy are activities that should not be ignored. Ultimately, they are the key to successful control of the health of both the baby and the mother.