Screening of the first trimester is a type of prenatal examination of a pregnant woman, which allows you to identify the possible risks of giving birth to a sick child. Diagnostic examination consists of fetal ultrasound and venous blood donation. The results obtained are compared with normal values, and depending on the individual factors of the pregnant woman, the geneticist predicts the chances that the child will be born with chromosomal diseases.

And now let's dwell on this in more detail.

Who is referred for 1st trimester screening?

In accordance with the order of the Ministry of Health of the Russian Federation No. 457 of December 28, 2000, all pregnant women should be sent for screening in the first trimester, especially if the woman is at risk of:

• over 35 years old;
• suffered unsuccessful pregnancies in the past, which ended in miscarriage, fading of pregnancy;
• works in hazardous production;
• already has a child with genetic diseases, or in past pregnancies during the screening of the first trimester, chromosomal abnormalities and intrauterine defects were detected;
• had an infection at the beginning of pregnancy;
• took medication, prohibited in the first trimester;
• suffering from drug addiction, alcoholism;
• if there is a threat of termination of pregnancy;
• potential parents are close relatives, or they had cases of hereditary diseases in their family.

Of course, a woman can refuse to conduct an analysis, but it would be reckless to do so, because the health of the unborn child depends on this.

Ultrasound as part of screening

Ultrasound examination allows you to identify and determine:

• uterine hypertonicity;
• examine the internal os of the uterus;
• location and thickness of the placenta;
• heart rate (HR) of the fetus;
• coccygeal-parietal size (KTR) is the distance from the head end of the fetus to its tailbone, not taking into account the length of the lower limbs;
• biparietal size (BPR) - the circumference of the fetal head;
• the structure of the brain;
• the thickness of the cervical fold or collar space (TVP);
• the length of the limbs of the fetus;
• localization of the stomach and heart;
• parameters of the heart, veins and arteries;
• volume of amniotic fluid;
• number of umbilical cord vessels.

What pathologies can be detected as a result of ultrasound?

Ultrasound screening of the first trimester allows you to identify such pathologies as:

• trisomy on chromosome 21, better known as one of the most common genetic diseases, thanks to this study, the frequency of the birth of children with such a pathology has decreased and if 1 child was born out of 700 pregnancies before, now out of 1100;
• trisomy 13 or, up to 95% of newborns due to damage to internal organs die in infancy;
• Edwards syndrome or trisomy 18, the risk of having such a child increases with age, most children with such abnormalities die in the first year of life due to cardiac or respiratory arrest;
• embryonic hernia - a pathology, which is characterized by the fact that part of the internal organs are located outside abdominal cavity in the hernial sac;
• Brahman-Lange syndrome, a disease that manifests itself as a lag in mental and physical development;
• Smith-Lemli-Opitz syndrome, the clinical picture of the pathology can vary greatly, such children may experience mental retardation of varying severity;
• neural tube defects (craniocerebral, spinal hernia, etc.).

The thickness of the collar space will help determine the likelihood of developing Down's disease. This indicator is determined during an ultrasound scan, but the exact result is determined after the establishment of blood test indicators.

A blood test involves the determination of indicators:

1. Hormone. Normally, this value gradually increases with the development of the gestational age. If the obtained indicator significantly exceeds the norm characteristic for a certain week, there is a risk of development, if the values ​​​​are lower -.
2. An indicator of plasma protein concentration. Deviations from the norm indicate the presence of a risk of developing pathologies in the future.

Ultrasound examination during the first screening allows you to determine:

• Availability ;
• the location of the fetus in the uterine cavity;
• establish multiple or singleton pregnancy;
• view embryo viability indicators;
• determine the KTP of the fetus;
• the presence of defects and pathologies of internal organs;
• check the indicators of the collar space (the norm for 10 weeks is 2 cm).

A comprehensive examination allows you to confirm or refute the presence of genetic-chromosomal disorders of the fetus.

Biopsy and amniocentesis are also performed to accurately determine fetal viability. In any case, the data obtained during the screening examination cannot be the main reason for termination of pregnancy. It is important to conduct a full examination in order to prevent making an erroneous decision.

Attention! If anomalies are detected in which the further normal life of the child is impossible, the girl may be offered an abortion.

Based on this information, it is worth emphasizing that screening is a necessary diagnostic method. Moms should remember that it is possible to issue a refusal to conduct a study, but the consequences can be irreversible.

Terms of the study

It is necessary to carry out diagnostics at a gestational period of 10-14 weeks. If screening is done earlier or later, the results will be incorrect.

In this case, the CTE of the fetus should be at least 45 mm. Its position should allow the uzist to evaluate all the parameters of fetometry. If the fetus is located unsuccessfully, the pregnant woman is asked to cough or walk around so that he changes his position and allows the doctor to consider its size.

Rules for preparing for the study

The study consists of two stages: ultrasound and blood donation.

1. First, a woman must undergo an ultrasound. It can take place transvaginally (no special preparation is needed) and transabdominally, while the woman's bladder must be full. Why should she not urinate at least 2 hours before the ultrasound, or should she drink 1.5 liters of water 30 minutes before the examination. Also, 1-3 days before the ultrasound, seafood, chocolate, citrus fruits, fatty and fried foods should be excluded from the diet.
2. After an ultrasound, a woman is sent for biochemical screening, blood is taken from her vein, it must be taken on an empty stomach. Prepare to donate blood:

• The last meal should be no later than 4 hours before blood donation.
• A diet should be followed for several days to avoid accidental distortion of the study data.
• The woman must remain calm.

Special preparation measures are not required, but it is necessary to follow the above recommendations. Some restrictions will reduce the risk of inadvertently distorting survey results.

How the study is done

Ultrasound examination is carried out by a sonologist - a specialist in a narrow focus in diagnostics. The employee is engaged in perinatal examinations. Ultrasound for a period of 10 - 12 weeks can be performed abdominally and transvaginally.

Most often, the transvaginal method of examination is chosen. To conduct an examination, a woman should take off her clothes below the waist, and lie on the couch with her legs bent. To conduct an examination, the doctor inserts a thin probe in a condom into the woman's vagina, during the examination it will be moved. A woman may experience mild discomfort with this, but not pain. After the study, a woman may find a small amount of discharge interspersed with blood on her underwear or pads - this is natural, there is no reason for concern.

The tansabdominal examination method is used less frequently. Doctors say that in the early stages this method may give some error. To conduct the examination, the woman lies on the couch and lifts the clothes in the abdomen. If there is a belt in the hip area, it should be removed. With this method of examination, the sensor is moved along the abdomen. The patient does not experience discomfort and pain.

Screening includes not only ultrasound, but also blood donation. The material for the study is the venous blood of a woman. The sampling is carried out in a specialized laboratory. About 10 ml of material is sufficient for the study.

Attention! Donate blood after an ultrasound. The doctor will need the results of an ultrasound examination for the correct interpretation of laboratory parameters.

Most often, private clinics provide results on the same day. The advantage of screening at commercial facilities is that the center provides the woman with a video recording of the ultrasound. State institutions, due to the large flow of patients and high workload, process the results within 3-5 days.

Deciphering the results

To correctly decipher the ultrasound, you need to know the normal indicators:

1. CTE is measured in millimeters. At week 10, the indicator can vary from 33 to 41 mm, at week 11 - from 42 to 50 mm, at week 12 - from 51 to 60 mm, at week 13 - from 62 to 73 mm. If this figure is too high, then most likely the pregnant woman will have to bear and give birth to a large baby. When the indicators are below the norm, then either the gestational age is set incorrectly, or the fetus has a genetic pathology, or it lags behind in development due to hormone deficiency, maternal diseases, including those of an infectious nature;
2. TVP at week 10 it can vary from 1.5 to 2.2 mm, at 11 - from 1.6 to 2.4 mm, at 12 - from 1.6 to 2.5 mm, at 13 - from 1.7 up to 2.7 mm. With genetic anomalies, as a rule, the collar space is expanded.
3. The nasal bone at 10-11 weeks is visible, but its size is not determined, at 12-13 weeks it should be at least 3 mm.
4. Fetal heart rate at 10 weeks should be from 161 to 179 beats per minute, at 11 weeks it can vary from 153 to 177 beats, at 12 weeks - from 150 to 174 beats, at 13 weeks - from 147 to 171 beats.
5. BDP: at 10 weeks - 14 mm, at 11 - 17 mm, at 12 - 20 mm, at 13 - 26 mm. If the indicator is above the norm, then this may indicate a large fetus, while other values ​​\u200b\u200bmust also be overestimated. Also, overestimated results can be with a brain tumor (this pathology is incompatible with life), with dropsy of the brain provoked by infections in a woman (pregnancy can be saved with adequate antibiotic therapy).

Based on the data obtained, the doctor makes a conclusion whether the development of the fetus is normal.

What hormone norms are determined by 1 screening

In addition to ultrasound, screening of the first trimester includes a biochemical blood test, which allows you to determine the level of hormones:

1. Chorionic gonadotropin or "pregnancy hormone", it begins to be produced immediately after conception. When, according to the result of prenatal diagnosis, it is below the norm, this may indicate about or about placental disorders. High rates are typical for multiple pregnancies and. measured in ng / ml: at week 10 it can vary from 25.8 to 181.60, at week 11 its values ​​\u200b\u200bshould be from 17.4 to 130.3, the norm for 12 weeks is from 13.4 to 128.5, at 13 weeks - from 14.2 to 114.8.
   PAPP-A or pregnancy-associated protein A, which is produced by the placenta, its level increases with increasing gestational age.

How to make sense of the data

There is a special program in which the obtained indicators are entered during ultrasound and blood biochemistry, and it calculates the final result, called "risks". On the form, they are recorded in the column "MoM" - a coefficient showing the deviation of the values ​​of a particular woman from the average normal values ​​(median).

If there are no pathologies, then the MoM values ​​should be in the range of 0.5-2.5, in the case when a multiple pregnancy is observed, MoM can reach 3.5. It is better if it is closer to 1. When calculating this coefficient, age risk must be taken into account. This means that the results obtained are compared not just with the median characteristic of this gestational age, but also calculated taking into account the age of the potential mother.

On the results form, the level of hormones can be recorded in units of MoM, for example, “hCG 1.58 MoM”, “PAPP-A 0.71 MoM”.

If the indicators are less than 0.5, then this may indicate a high probability of having a child with, the threat of miscarriage, placental insufficiency. When it goes beyond the upper limit of the norm, then there is a high risk of trisomy on chromosome 21.

If the PAPP-A indicators are underestimated, then there is a risk of having a child, Edwards, Brahman-Lange. Isolated overestimated results have no diagnostic value.

Risk assessment

After the results of the tests are received, the risks of having a child with anomalies are assessed. They are expressed in fractions, for example, 1:260, which means that 1 pregnant woman due to 260 has a chance of having a child with genetic abnormalities.

At low risk, these values ​​should be greater than 1:380 and the screening result should be negative. With such results, it means that the child is healthy.

The first screening is considered bad if the risk is high, its level is from 1:250 to 1:380, and MoM is also outside the normal range.
In this case, the pregnant woman is referred to a geneticist who chooses further tactics:

• wait for the results of screening II and III trimester;
• send to additional examinations: a biopsy of the chorionic villi, a study of the umbilical cord blood of the fetus, the study of amniotic fluid and, based on their data, the doctor will decide whether to continue the pregnancy.

What can distort the result

Screening results can be false positive:

1. If the pregnancy occurred as a result of artificial insemination, then on ultrasound the frontal-occipital size of the fetus will be increased, an overestimation of the hCG value will be detected in the blood, while PAPP will be 10-15% less.
2. In overweight women, the concentration of all hormones increases, with a lack of mass - it decreases.
3. There are currently no known normal values ​​for multiple pregnancies. In this case, only an ultrasound is performed.
4. If a woman suffers, the concentration of hormones will be below normal.
5. When carrying out amniocentesis (puncture of amniotic fluid), indicators of prenatal diagnosis may change. And since it is not known what the normal values ​​\u200b\u200bshould be, then at least a week should pass between these two studies.
6. The emotional state of a woman: fear can affect the final result, and no one can say how.

Some features of fetal anomalies

If the fetus has any pathologies, then screening will have a number of features:

1. . It is characterized by the fact that at a gestational age of 10-14 in most fetuses the nasal bone is not visualized, and at a period of 15-20 weeks it is visible, but it is shorter than the norm. In addition, it can be noted that the fetus has smoothed facial features, there is a violation of blood circulation in the venous duct, and the size of the bladder is increased.
2. For the characteristic following deviation from the norm: the nasal bone is not visible, a hernia of the umbilical cord is observed, the umbilical cord has one artery, not two, the heart rate is below normal.
3. With Patau's syndrome, the doctor can examine the embryonic hernia, the structure of the brain is changed, the size of the bones of the fetus is smaller than normal, and there is almost always an increase in heart rate.

Some features in pathology

It should be borne in mind that some deviations in the results may not indicate the presence of pathology.

Minor deviations are natural for the following groups of patients:

• persons suffering from systemic diseases;
• with artificial insemination;
• in overweight patients;
• in multiple pregnancies.

1st trimester screening price

The cost of the survey can vary significantly depending on the region of the Russian Federation. Such a service is somewhat more expensive in private medical centers.

The cost can be paid separately:

• blood test - 1700-3600 grew. rub;
• Ultrasound - 1200-2700 grew. rub.

Women should remember that pregnancy is not only expected and desired, but also a dangerous condition that requires constant medical supervision, and screening is the most effective method for detecting fetal abnormalities on early dates.

The Center for Immunology and Reproduction has been successfully working for many years program prenatal screening . Our specialists are invited to give lectures at specialized conferences and in other clinics. Our laboratory receives consistently good marks in the quality control system. Specially trained specialists carry out risk assessment.

What is prenatal diagnosis?

The word "prenatal" means "prenatal". Therefore, the term "prenatal diagnosis" means any research that allows you to clarify the condition intrauterine fetus. Since human life begins from the moment of conception, various health problems can occur not only after birth, but also before birth. Problems can be different:

• fairly harmless, with which the fetus can handle itself,
• more serious, when timely medical care will save the health and life of the intrauterine patient,
• severe enough that modern medicine can not cope.

To determine the health status of the fetus, prenatal diagnostic methods are used, which include ultrasonography, cardiotocography, various biochemical studies, etc. All these methods have different capabilities and limitations. Some methods are quite safe, such as ultrasound. Some carry some risk to the fetus, such as amniocentesis (amniotic fluid sampling) or chorionic villus sampling.

It is clear that methods of prenatal diagnosis, associated with the risk of pregnancy complications, should be used only when there are strong indications for their use. In order to narrow the circle of patients who need invasive (i.e., those associated with intervention in the body) methods of prenatal diagnosis as much as possible, a selection is used risk groups the development of certain problems in the fetus.

What are risk groups?

Risk groups are such groups of patients among whom the probability of detecting a particular pathology of pregnancy is higher than in the entire population (among all women in a given region). There are risk groups for the development of miscarriage, preeclampsia (late toxicosis), various complications in childbirth, etc. If a woman, as a result of an examination, is at risk for a particular pathology, this does not mean that this pathology will necessarily develop. This only means that in this patient one or another type of pathology may occur with a greater probability than in other women. Thus, the risk group is not identical to the diagnosis. A woman may be at risk, but there may not be any problems during pregnancy. And vice versa, a woman may not be at risk, but she may have a problem. Diagnosis means that this or that pathological condition has already been detected in this patient.

Why are risk groups important?

Knowing that the patient is in a particular risk group helps the doctor to plan the tactics of pregnancy and childbirth correctly. Identification of risk groups helps protect patients who are not at risk from unnecessary medical interventions, and vice versa, allows you to justify the appointment of certain procedures or studies for patients at risk.

What is screening?

The word screening means "sifting". In medicine, screening is understood as the conduct of simple and safe studies of large groups of the population in order to identify risk groups for the development of a particular pathology. Prenatal screening refers to studies conducted on pregnant women to identify risk groups for pregnancy complications. A special case of prenatal screening is screening to identify risk groups for the development of congenital malformations in the fetus. Screening does not allow to identify all women who may have a particular problem, but it makes it possible to identify a relatively small group of patients, within which most of the people with this type of pathology will be concentrated.

Why screening for fetal malformations is needed?

Some types of congenital malformations in the fetus are quite common, for example, Down's syndrome (trisomy on the 21st pair of chromosomes or trisomy 21) - in one case in 600 - 800 newborns. This disease, like some other congenital diseases, occurs at the moment of conception or at the very early stages development of the embryo and using invasive methods of prenatal diagnosis (chorionic villus biopsy and amniocentesis) can be diagnosed at a fairly early stage of pregnancy. However, such methods are associated with a risk of a number of pregnancy complications: miscarriage, the development of a conflict in the Rh factor and blood type, infection of the fetus, the development of hearing loss in a child, etc. In particular, the risk of miscarriage after such studies is 1:200. Therefore, these studies should be prescribed only to women in high risk groups. Risk groups include women over 35 and especially over 40, as well as patients with the birth of children with malformations in the past. However, children with Down syndrome can also be born to very young women. Screening methods - completely safe studies conducted at certain stages of pregnancy - allow with a very high degree of probability to identify groups of women at risk of Down's syndrome, who may be indicated for chorionic villus biopsy or amniocentesis. Women who are not at risk do not need additional invasive studies. Finding an increased risk of fetal malformations through screening methods is not a diagnosis. The diagnosis can be made or rejected with additional tests.

What types of birth defects are screened for?

• Down syndrome (trisomy of the twenty-first pair of chromosomes)
• Edwards syndrome (trisomy eighteenth pair)
• Neural tube defects (spina bifida and anencephaly)
• Smith-Lemli-Opitz syndrome
• Corneli de Lange syndrome

What types of tests are performed as part of the screening for the risk of fetal malformations?

By types of research allocate:

• Biochemical screening: blood test for various indicators
• Ultrasound screening: detection of signs of developmental anomalies using ultrasound.
• Combined screening: a combination of biochemical and ultrasound screenings.

The general trend in the development of prenatal screening is the desire to obtain reliable information about the risk of developing certain disorders as early as possible in pregnancy. It turned out that combined screening at the end of the first trimester of pregnancy (terms of 10-13 weeks) makes it possible to approach the effectiveness of classical biochemical screening of the second trimester of pregnancy.

Ultrasound screening, used for mathematical processing of the risks of fetal anomalies, is carried out only 1 time: at the end of the first trimester of pregnancy.

Concerning biochemical screening, then the set of indicators will be different at different stages of pregnancy. During pregnancy 10-13 weeks The following parameters are checked:

• free β-subunit of human chorionic hormone (free β-hCG)
• PAPP-A (pregnancy associated plasma protein A), pregnancy-associated plasma protein A

The calculation of the risk of measuring fetal anomalies, based on the measurement of these indicators, is called double biochemical test first trimester of pregnancy.

Using a double test in the first trimester, the risk of detection in the fetus is calculated Down syndrome (T21) And Edwards syndrome (T18), trisomy on chromosome 13 (Patau syndrome), triploidy of maternal origin, Shereshevsky-Turner syndrome without dropsy. The risk of neural tube defects cannot be calculated using the dual test, since the key indicator for determining this risk is α-fetoprotein, which begins to be measured only from the second trimester of pregnancy.

Special computer programs make it possible to calculate the combined risk of fetal anomalies, taking into account the biochemical parameters determined in the first trimester double test and the results of an ultrasound scan taken at 10-13 weeks of gestation. Such a test is called combined with TVP double test of the first trimester of pregnancy or triple test first trimester of pregnancy. The results of risk calculations obtained using a combined double test are much more accurate than risk calculations based only on biochemical parameters or only on the basis of ultrasound.

If the results of the test in the first trimester indicate a risk group for chromosomal abnormalities of the fetus, the patient may be performed to exclude the diagnosis of chromosomal abnormalities chorionic villus biopsy.

During pregnancy 14 - 20 weeks by last menstrual period recommended terms: 16-18 weeks) the following biochemical indicators are determined:

• α-fetoprotein (AFP)
• Inhibin A

Based on these indicators, the following risks are calculated:

• Down syndrome (trisomy 21)
• Edwards syndrome (trisomy 18)
• neural tube defects (non-closure of the spinal canal (spina bifida) and anencephaly).
• Risk of trisomy 13 (Patau syndrome)
• Triploid maternal origin
• Shereshevsky-Turner syndrome without dropsy
• Smith-Lemli-Opitz syndrome
• Corneli de Lange syndrome

Such a test is called Quadruple test in the second trimester of pregnancy or quadruple biochemical screening in the second trimester of pregnancy. A truncated version of the test is the so-called triple or double tests of the second trimester, which includes 2 or indicators: hCG or free hCG β-subunit, AFP, free estriol. It is clear that the accuracy of the double or double II trimester test is lower than the accuracy of the quadruple II trimester test.

Another option for biochemical prenatal screening is biochemical screening for the risk of only neural tube defects in the second trimester of pregnancy. In this case, only one biochemical marker is determined: α-fetoprotein

When is the second trimester screening done in pregnancy?

At 14 - 20 weeks of pregnancy. The optimal period is 16 - 18 weeks of pregnancy.

What is a 2nd trimester quad test?

The main option for biochemical screening of the second trimester in the CIR is the so-called quadruple or quadruple test, when the determination of inhibin A is added to the determination of the three above indicators.

Ultrasound screening in the first trimester of pregnancy.

In the first trimester of pregnancy, the main dimension used in calculating risks is the width of the cervical translucency (English "nuchal translucency" (NT) , French "clarté nuchale"). In Russian medical usage, this term is often translated as "collar space" (TVP) or "neck fold". Cervical transparency, collar space and cervical fold are full synonyms that can be found in various medical texts and mean the same thing.

Cervical transparency - definition

• Cervical transparency is what an accumulation of subcutaneous fluid on the back of the fetal neck looks like on ultrasound during the first trimester of pregnancy.
• The term "cervical transparency" is used regardless of whether it has septa or whether it is limited to the cervical region or surrounds the entire fetus.
• The frequency of chromosomal and other anomalies is primarily related to the width of the transparency, and not how it looks in general.
• During the second trimester, the transparency usually resolves, but in some cases it can turn into either cervical edema or cystic hygromas with or without generalized edema.

Measurement of cervical transparency

Terms of pregnancy and coccyx-parietal size

The optimal gestational age for measuring NB is 11 weeks to 13 weeks 6 days. The minimum size of the KTP is 45 mm, the maximum is 84 mm.

There are two reasons for choosing 11 weeks as the earliest time to measure NB:

1. Screening requires the ability to perform a chorionic villus biopsy before the time when this study may be complicated by amputation of the fetal limbs.
2. On the other hand, many gross fetal defects can only be detected after 11 weeks of pregnancy.

• The diagnosis of omphalocele is possible only after 12 weeks.
• Diagnosis of anencephaly is possible only after 11 weeks of pregnancy, since only from this period do ultrasound signs of ossification of the fetal skull appear.
• Assessment of the four-chambered heart and large vessels is possible only after 10 weeks of pregnancy.
• The bladder is visualized in 50% of healthy fetuses at 10 weeks, in 80% at 11 weeks, and in all fetuses at 12 weeks.

Image and measurement

For measurement of bandwidth ultrasound machine should be of high resolution with video loop function and calibrators that can measure size to tenths of a millimeter. SP can be measured with an abdominal probe in 95% of cases, in cases where this cannot be done, a vaginal probe should be used.

When measuring NR, only the head and upper part should be included in the picture. chest fetus. The magnification should be maximum, so that a small shift of the markers gives a change in measurement of no more than 0.1 mm. When zooming in on an image, either before or after fixing the image, it is important to reduce the gain. This avoids a measurement error when the marker falls into a blurred area and thus the size of the NR will be underestimated.

A good sagittal section should be obtained, of the same quality as when measuring CTE. The measurement should be made in the neutral position of the fetal head: extension of the head can increase the value of TBP by 0.6 mm, flexion of the head can decrease the value by 0.4 mm.

It is important not to confuse the skin of the fetus with the amnion, because at this stage of pregnancy, both formations look like thin membranes. If in doubt, you should wait for the moment when the fetus makes a movement and moves away from the amnion. An alternative way is to ask the pregnant woman to cough or lightly tap on the pregnant woman's abdominal wall.

The largest perpendicular distance between the internal contours of the cervical transparency is measured (see figure below). Measurements are taken three times, the largest value of the size is used for the calculation. In 5-10% of cases, the umbilical cord is found wrapped around the fetal neck, which can greatly complicate measurement. In such cases, 2 measurements are used: above and below the cord entanglement, the average of these two measurements is used to calculate the risks.

Standards for ultrasound scanning at the end of the first trimester of pregnancy are being developed by the England-based Fetal Medicine Foundation (FMF). In the CIR group of companies, ultrasound is performed according to the FMF protocol.

Additional Ultrasound Signs of Down Syndrome Risk

Recently, in addition to the measurement of SP for the diagnosis of Down syndrome at the end of the first trimester of pregnancy, the following ultrasound signs are used:

• Definition of the nasal bone. At the end of the first trimester, the nasal bone not defined using ultrasound in 60-70% of fetuses with Down syndrome and only in 2% of healthy fetuses.
• Assessment of blood flow in the Arantzian (venous) duct. Abnormalities in the waveform of blood flow in the duct of Arantia are found in 80% of fetuses with Down syndrome and only in 5% of chromosomally normal fetuses.
• Reducing the size of the maxillary bone
• Bladder enlargement (“megacystitis”)
• Moderate tachycardia in the fetus

The form of blood flow in the duct of Arantzium with dopplerometry. Top: normal; bottom: with trisomy 21.

Not only Down syndrome!

During the ultrasound at the end of the first trimester, the assessment of the fetal contour delivers to reveal the following fetal anomalies:

• Exencephaly - anencephaly
• Cystic hygroma (swelling at the level of the neck and back of the fetus), more than half of the cases due to chromosomal abnormalities
• Omphalocele and gastroschisis. The diagnosis of omphalocele can only be made after 12 weeks of pregnancy, since before this period the physiological umbilical hernia, fairly common, has no clinical significance
• The only umbilical artery (in a large percentage of cases it is combined with chromosomal abnormalities in the fetus)

How are risks calculated?

Special software is used to calculate risks. Simply determining the level of indicators in the blood is not enough to decide whether the risk of developmental anomalies is increased or not. The software must be certified for use with prenatal screening. At the first stage of computer calculation, the figures of indicators obtained during laboratory diagnostics are converted into the so-called MoM (multiple of median, a multiple of the median), characterizing the degree of deviation of one or another indicator from the median. At the next stage of the calculation, the MoM is adjusted for various factors (a woman's body weight, race, the presence of certain diseases, smoking, multiple pregnancy, etc.). The result is the so-called adjusted MoM. In the third step of the calculation, the adjusted MoMs are used to calculate the risks. The software is specially configured for the methods used in the laboratory for determining indicators and reagents. It is unacceptable to calculate risks using analyzes made in another laboratory. The most accurate calculation of the risks of fetal anomalies is when using data from an ultrasound scan performed at 10-13 weeks of gestation.

What is MOM?

MoM is the English abbreviation for the term “multiple of median”, which means “multiple of the median”. This is a coefficient showing the degree of deviation of the value of one or another indicator of prenatal screening from the average value for the gestational age (median). MoM is calculated using the following formula:

MoM = [Mean value in patient's serum] / [Median value for gestational age]

Because the measure value and the median share the same units, the MoM value has no units. If the value of MoM in a patient is close to one, then the value of the indicator is close to the average in the population; if it is above one, it is above the average in the population; if it is below one, it is below the average in the population. With congenital malformations of the fetus, there may be statistically significant deviations of MoM markers. However, in its pure form, MoMs are almost never used in calculating the risk of fetal anomalies. The fact is that in the presence of a number of factors, the average values ​​of MoM deviate from the average in the population. Such factors include the patient's body weight, smoking, race, pregnancy as a result of IVF, etc. Therefore, after obtaining the MoM values, the risk calculation program makes an adjustment for all these factors, resulting in the so-called “adjusted MoM value”, which used in risk calculation formulas. Therefore, in the conclusion forms based on the results of the analysis, next to the absolute values ​​of the indicators, the adjusted MoM values ​​for each indicator are indicated.

Typical MoM profiles in pregnancy pathology

With various fetal anomalies, MoM values ​​are combined deviated from the norm. Such combinations of MoM deviations are called MoM profiles for a particular pathology. The tables below show typical MoM profiles for different terms pregnancy.

Typical MoM Profiles - First Trimester

Typical MoM Profiles - Second Trimester

Indications for 1st and 2nd trimester prenatal screening for risk of fetal anomalies

Prenatal screening is now recommended for all pregnant women. The order of the Ministry of Health of the Russian Federation of 2000 obliges antenatal clinics to conduct biochemical prenatal screening for all pregnant patients in the second trimester of pregnancy for two indicators (AFP and hCG).

Order No. 457 of December 28, 2000 “On improving prenatal diagnosis in the prevention of hereditary and congenital diseases in children”:

“At 16-20 weeks, take blood from all pregnant women to conduct studies of at least two serum markers (AFP, hCG)”

The importance of monitoring congenital diseases on an ongoing basis in Moscow is also discussed in the Moscow government's decree on the establishment of the city's Children's Health Program for 2003-2005.

"It is advisable to start genetic monitoring of congenital malformations of newborns, prenatal screening for Down's disease and neural tube defects in Moscow"

On the other hand, prenatal screening should be purely voluntary. In most Western countries, it is the physician's responsibility to inform the patient about the possibility of such studies and about the goals, possibilities and limitations of prenatal screening. The patient herself decides whether to do her tests or not. The same point of view is shared by the CIR group of companies. The main problem is that there is no cure for the detected anomalies. If the presence of anomalies is confirmed, the couple is faced with a choice: terminate the pregnancy or keep it. It's not an easy choice.

What is Edwards Syndrome?

This is a condition caused by the presence of an extra 18th chromosome in the karyotype (trisomy 18). The syndrome is characterized by gross physical anomalies and mental retardation. This is a lethal condition: 50% of sick children die in the first 2 months of life, 95% - during the first year of life. Girls are affected 3-4 times more often than boys. The frequency in the population ranges from 1 case per 6,000 births to 1 case per 10,000 births (about 10 times less than Down syndrome).

What is the free β-subunit of hCG?

Molecules of a number of pituitary and placental hormones (thyroid-stimulating hormone (TSH), follicle-stimulating hormone (FSH), luteinizing hormone (LH) and human chorionic hormone (hCG)) have a similar structure and consist of α and β subunits. The alpha subunits of these hormones are very similar and the main differences between the hormones are in the structure of the β subunits. LH and hCG are very similar not only in the structure of the α-subunits, but also in the structure of the β-subunits. That is why they are hormones with the same action. During pregnancy, LH production by the pituitary gland drops to almost zero, and hCG concentrations are very high. The placenta produces very large quantities hCG, and although this hormone mainly enters the blood in an assembled form (a dimeric molecule consisting of both subunits), a small amount of free (not associated with the α-subunit) β-hCG subunit also enters the bloodstream. Its concentration in the blood is many times less than the concentration of total hCG, but this indicator can more reliably indicate the risk of problems in the fetus in the early stages of pregnancy. The determination of the free β-subunit of hCG in the blood is also important for the diagnosis of trophoblastic disease (molar mole and chorionepithelioma), some testicular tumors in men, and monitoring the success of in vitro fertilization procedures.

Which indicator: total hCG or free β-hCG subunit - is it preferable to use in the second trimester triple test?

Using free hCG β-subunit determination compared to total hCG determination gives a more accurate estimate of the risk of Down syndrome, however, in the classic statistical calculations of the risk of Edwards syndrome in the population, the determination of the level of total hCG in the mother's blood was used. For the β-subunit of hCG, no such calculations have been made. Therefore, a choice must be made between exact calculation the risk of Down syndrome (in the case of the β-subunit) and the ability to calculate the risk of Edwards syndrome (in the case of total hCG). Recall that in the first trimester, only free β-subunit hCG is used to calculate the risk of Edwards syndrome, but not total hCG. Edwards syndrome is characterized by low numbers of all 3 indicators of the triple test, therefore, in such cases, both variants of the triple test (with total hCG and with free β-subunit) can be done.

What is PAPP-A?

Pregnancy-associated plasma protein-A (PAPP-A) was first described in 1974 as a high molecular weight protein fraction in the blood serum of women in late pregnancy. It turned out to be a large zinc-containing metalglycoprotein with a molecular weight of about 800 kDa. During pregnancy, PAPP-A is produced by syncytiotrophoblast (the tissue that is the outer layer of the placenta) and extravillous cytotrophoblast (islands of fetal cells in the thickness of the uterine lining) and enters the mother's bloodstream.

The biological significance of this protein is not fully understood. It has been shown to bind heparin and is an inhibitor of granulocyte elastase (an enzyme induced by inflammation), so it is suggested that PAPP-A modulates the immune response. maternal organism and is one of the factors that ensures the development and survival of the placenta. In addition, it was found that it is a protease that cleaves protein 4 that binds insulin-like growth factor. There are serious reasons to believe that PAPP-A is one of the factors of paracrine regulation not only in the placenta, but also in some other tissues, in particular, in atherosclerotic plaques. It is proposed to use this marker as one of the risk factors for coronary heart disease.

Maternal blood concentrations of PAPP-A steadily increase with increasing gestational age. The greatest increase in this indicator is observed at the end of pregnancy.

Over the past 15 years, PAPP-A has been studied as one of three risk markers for trisomy 21 (Down syndrome) (together with free hCG β-subunit and nuchal thickness). It turned out that the level of this marker at the end of the first trimester of pregnancy (8-14 weeks) is significantly reduced if the fetus has trisomy 21 or trisomy 18 (Edwards syndrome). The uniqueness of this indicator is that its significance as a marker of Down syndrome disappears after 14 weeks of pregnancy. In the second trimester, its levels in maternal blood in the presence of trisomy 21 in the fetus do not differ from those in pregnant women with a healthy fetus. If we consider PAPP-A as an isolated marker of the risk of Down syndrome in the first trimester of pregnancy, its determination at 8-9 weeks would be the most significant. However, the free β-subunit of hCG is a stable marker of the risk of Down syndrome at 10-18 weeks, i.e. later than PAPP-A. Therefore, the optimal time for donating blood for a double test in the first trimester of pregnancy is 10-12 weeks.

The combination of PAPP-A measurement with the determination of the concentration of free β-hCG subunit in the blood and the determination of TVP using ultrasound at the end of the first trimester of pregnancy can identify up to 90% of women at risk of developing Down syndrome in the older age group (after 35 years). The probability of false positive results is about 5%.

In addition to prenatal screening for the risk of Down syndrome and Edwards syndrome, in obstetrics, the definition of PAPP-A is also used for the following types of pathology:

• The threat of miscarriage and stopping the development of pregnancy in the short term
• Cornelia de Lange syndrome.

Risk Diagnostics arrest of fetal development in early pregnancy was historically the first clinical application for serum PAPP-A, proposed in the early 1980s. Women with low levels of PAPP-A in early pregnancy have been shown to be at risk of subsequent pregnancy arrest and severe forms of late toxicosis. Therefore, it is recommended that this indicator be determined within 7-8 weeks for women with a history of severe pregnancy complications.

Cornelia de Lange syndrome is a rare form of congenital malformation of the fetus, found in 1 case in 40,000 births. The syndrome is characterized by mental retardation and physical development, heart and limb defects and characteristic features of facial features. It has been shown that in this condition, the levels of PAPP-A in the blood at 20-35 weeks are significantly lower than normal. A study by Aitken's group in 1999 showed that this marker can be used to screen for Cornelia de Lange syndrome in the second trimester of pregnancy, since the levels of the indicator in such pregnant women were on average 5 times lower than normal.

The reagents used to determine PAPP-A and the free β-subunit of hCG are an order of magnitude more expensive than those used for most hormonal parameters, which makes this test more expensive than most reproductive hormones.

What is α-fetoprotein?

It is a fetal glycoprotein produced first in the yolk sac and then in the liver and gastrointestinal tract of the fetus. It is a transport protein in the blood of the fetus that binds a number of different factors (bilirubin, fatty acids, steroid hormones). It is a dual fetus growth regulator. In an adult, AFP does not perform any known functions, although it can increase in the blood in liver diseases (cirrhosis, hepatitis) and in some tumors (hepatocellular carcinoma and germinal carcinoma). In the mother's blood, the level of AFP gradually increases with increasing gestational age and reaches a maximum by 30 weeks. The level of AFP in the mother's blood increases with neural tube defects in the fetus and with multiple pregnancies, and decreases with Down syndrome and Edwards syndrome.

What is free estriol?

Estriol is synthesized in the placenta from 16α-hydroxy-dehydroepiantrosterone sulfate supplied by the fetus. The main source of estriol precursors is the fetal adrenal glands. Estriol is the main estrogenic hormone of pregnancy and ensures the growth of the uterus and the preparation of the mammary glands for lactation.

90% of estriol after 20 weeks of pregnancy is formed from fetal DEA-C. A large output of DEA-C from the adrenal gland of the fetus is associated with low activity of 3β-hydroxysteroid dehydrogenase in the fetus. A protective mechanism that protects the fetus from excess androgenic activity is the rapid conjugation of steroids with sulfate. The fetus produces more than 200 mg of DEA-C per day, 10 times more than the mother. In the maternal liver, estriol is rapidly conjugated with acids, mainly hyaluronic acid, and thus inactivated. The most accurate method for determining the activity of the fetal adrenal glands is to determine the level of free (unconjugated) estriol.

The level of free estriol gradually rises as pregnancy progresses and in the third trimester of pregnancy can be used to diagnose fetal well-being. With a deterioration in the condition of the fetus in the third trimester of pregnancy, a sharp drop in the level of free estriol can be observed. Free estriol levels are often low in Down syndrome and Edwards syndrome. Taking dexamethasone, prednisolone or metipred during pregnancy suppresses the function of the fetal adrenal glands, so the level of free estriol in such patients is often reduced (decrease in the supply of estriol from the fetus). When taking antibiotics, the rate of estriol conjugation in the mother's liver increases and the reabsorption of conjugates from the intestine decreases, so the level of estriol also decreases, but by accelerating its inactivation in the mother's body. For an accurate interpretation of the triple test data, it is very important that the patient indicate full list medicines taken or taken during pregnancy with doses and timing of administration.

Algorithm for prenatal screening I and II trimester of pregnancy.

1. We calculate the duration of pregnancy, it is better after consulting a doctor or with the help of a consultant.

Screening of the first trimester has its own characteristics. It is carried out in terms of 10 - 13 weeks of pregnancy and is quite strictly limited in time. If you donate blood too early or too late, if you make a mistake in calculating the gestational age at the time of donating blood, the accuracy of the calculation will decrease dramatically. Pregnancy terms in obstetrics are usually calculated on the first day of the last menstruation, although conception occurs on the day of ovulation, that is, with a 28-day cycle - 2 weeks after the first day of menstruation. Therefore, the terms of 10 - 13 weeks on the day of menstruation correspond to 8 - 11 weeks of conception.

To calculate the gestational age, we recommend using the obstetric calendar posted on our website. Difficulties in calculating the timing of pregnancy can be with irregular menstrual cycle, during pregnancy, which occurred shortly after childbirth, with a cycle that deviates more than a week from 28 days. Therefore, it is best to trust professionals, and to calculate the duration of pregnancy, conduct an ultrasound scan and donate blood, consult a doctor.

2. We do an ultrasound.

The next step should be an ultrasound scan at 10-13 weeks of gestation. The data from this study will be used by the risk calculation program in both the first and second trimesters. It is necessary to start the examination with ultrasound, since during the study problems with the development of pregnancy (for example, a stop or lag in development), a multiple pregnancy, the timing of conception will be accurately calculated. The doctor conducting the ultrasound will help the patient calculate the timing of blood donation for biochemical screening. If the ultrasound is done too early in terms of pregnancy, then the doctor may recommend repeating the study after some time.

To calculate the risks, the following data from the ultrasound report will be used: the date of the ultrasound, the coccygeal-parietal size (CTE) and the thickness of the collar space (NTP) (English abbreviations, respectively, CRL and NT), as well as visualization of the nasal bones.

3. We donate blood.

Having the results of the ultrasound and knowing the exact gestational age, you can come for blood donation. Blood sampling for analysis for prenatal screening in the CIR group of companies is carried out daily, including weekends. On weekdays, blood sampling is carried out from 7:45 to 21:00, on weekends and holidays: from 8:45 to 17:00. Blood sampling is carried out 3-4 hours after the last meal.

In terms of pregnancy 14-20 weeks after the last menstruation (recommended terms: 16-18 weeks), the following biochemical parameters are determined:

• Total hCG or free β-hCG subunit
• α-fetoprotein (AFP)
• Free (unconjugated) estriol
• Inhibin A

4. We get the result.

Now we need to get the results of the analysis. The turnaround time for the results of prenatal screening analysis in the CIR group of companies is one business day (except for the fourth test). This means that tests taken from Monday to Friday will be ready on the same day, and those taken from Saturday to Sunday on Monday.

Conclusions on the results of the study are issued to the patient in Russian.

Tiblitsa. Explanation of terms and abbreviations

Report date	Date of computer processing of results
Gestational age	Weeks + days
Date of ultrasound	Date of the ultrasound. Usually does not coincide with the date of blood donation.
Fruit	The number of fruits. 1 - singleton pregnancy; 2 - twins; 3 - triplets
ECO	Pregnancy as a result of IVF
KTR	Coccyx-parietal size determined during ultrasound
MoM	Multiple of median, the degree of deviation of the result from the average for a given gestational age
Corr. MoM	Adjusted MoM. MoM value after adjustment for body weight, age, race, number of fetuses, diabetes, smoking, IVF infertility treatment.
NT	The thickness of the collar space (nuchal translucency). Synonym: neck fold. In various versions of reports, either absolute values ​​​​in mm or the degree of deviation from the median (MoM) can be given
age risk	The average risk for this age group. No factors other than age are taken into account.
Tr. 21	Trisomy 21, Down syndrome
Tr. 18	Trisomy 18, Edwards syndrome
biochemical risk	The risk of fetal anomalies after computer processing of blood test data without taking into account ultrasound data
Combined Risk	The risk of fetal anomalies after computer processing of blood test data, taking into account ultrasound data. The most accurate indicator of the degree of risk.
fb-HCG	Free β-hCG subunit
PDM	Date of last menstrual period
AFP	α-fetoprotein
HCG	Total hCG (human chorionic gonadotropin)
uE3	Free estriol (unconjugated estriol)
+NT	The calculation was carried out taking into account ultrasound data
mIU/ml	mIU/ml
ng/ml	ng/ml
IU/ml	IU/ml

Additional Information.

Information for patients: Please note that if you plan to undergo prenatal screening in the CIR group of companies, then the ultrasound data made in other institutions will be taken into account only if there is a special agreement between the CIR group of companies and these institutions.

Information for doctors

Dear Colleagues! In accordance with the Order of the Ministry of Health No. 457 and Decree of the Government of Moscow No. 572, the CIR group of companies provides services to other medical institutions for prenatal screening for the risk of chromosomal abnormalities. You can invite our staff to come to you with a lecture on this program. To refer a patient for screening, the attending physician must complete a special referral. The patient can come to donate blood on her own, but it is also possible to take blood in other institutions with subsequent delivery to our laboratory, including by our courier. If you want to receive the results of double, triple and quadruple tests of the first and second trimesters of pregnancy, combined with ultrasound data, the patient must come to us for an ultrasound scan, or we must sign a special agreement with your institution and include your ultrasound specialists in the program, but only after departure of our expert in functional diagnostics to your institution and familiarization with the quality of the equipment and the qualifications of specialists.

Screening helps to identify pathology in the early stages of fetal development. This set of diagnostic measures is aimed at assessing the rate of intrauterine development of the baby by comparing the indicators with the gestational age. The procedure is mandatory and is carried out for all expectant mothers.

Why is screening necessary during pregnancy?

Screening during pregnancy is a mandatory procedure, during which the risk of developing abnormalities in the fetus is established. Diagnostic procedures help to identify a predisposition to the development of genetic abnormalities of the fetus, to establish a discrepancy between the development of the internal organs of the baby and the gestational age.

The procedure is advisory in nature, but women never refuse to conduct it, knowing the significance of such studies. There are also indications, the presence of which determines the mandatory conduct of the study:

• the age of the woman is more than 35 years;
• Availability ;
• history of spontaneous abortion;
• the presence of fetal chromosomal abnormalities in past pregnancies;
• transferred infections in the short term;
• forced intake of drugs that are contraindicated for short periods;
• the presence of bad habits (alcoholism, drug addiction);
• close relationship between the father and mother of the child.

1st trimester screening - what is it?

The first screening during pregnancy is a comprehensive examination of the maternal body. In its implementation, doctors pursue the goal early diagnosis and further correction of fetal anomalies. In parallel, an assessment of the health status of the expectant mother is also carried out. Screening of the 1st trimester consists of an ultrasound and a biochemical study of the blood of a pregnant woman. The evaluation of blood parameters is carried out at the second stage, in the presence of deviations and suspicions of pathology based on the results of ultrasound. The stages are carried out sequentially, it is allowed to carry out two procedures on the same day.

Ultrasound screening 1st trimester

Ultrasound during pregnancy is important. With the help of ultrasound, doctors manage to look into the mother's womb, assess the state of a small organism, its internal organs. In the course of such a study, as part of the screening of the 1st trimester, doctors pay attention to anthropometric indicators, which are an indicator of the correct development of the fetus, the correspondence of the size of its body to the gestational age. When the screening of the 1st trimester is carried out, the doctor pays attention to the following parameters:

• KTP (coccyx-parietal size);
• the size of the fetal head;
• symmetry of the cerebral hemispheres;
• the size of long tubular bones;
• the size of the heart and the diameter of the vessels departing from it;
• localization of the stomach and other internal organs.

Biochemical screening of the 1st trimester

Doctors prescribe such tests during pregnancy after receiving a bad ultrasound result. Suspecting a pathology on the monitor screen, doctors want to make sure the objectivity of the assumptions put forward. It is worth noting that this study should be carried out exclusively at a certain gestational age, since the norms of indicators directly depend on the stage of gestation. In a biochemical blood test, attention is paid to the following indicators:

What does the first screening show?

During the first screening, doctors try to exclude possible chromosomal abnormalities. These violations do not manifest themselves outwardly, their presence does not affect the condition of a pregnant woman. However, they can be identified by characteristic changes in the appearance of the fetus and by the presence of certain markers in the blood of the expectant mother. Among the possible pathologies that screening of the 1st trimester helps to identify:

1. Down syndrome- chromosomes, occurs in 1 out of 700 cases.
2. Neural tube pathologies(encephalocele).
3. Omphalocele- with this pathology, part of the internal organs is placed under the skin of the anterior abdominal wall, in the hernial sac.
4. Patau Syndrome- trisomy on chromosome 13. Rare, 1 in 10,000 pregnancies. Accompanied by severe damage to internal organs. 90% of babies born with this pathology die during the first year of life.
5. Edwards syndrome Trisomy 18 chromosome. Occurs in 1 out of 7000 cases. It often occurs in old-born mothers (pregnant women after 35 years).
6. triploidy- the baby is diagnosed with a triple set of chromosomes, which is accompanied by multiple malformations.
7. Cornelia de Lange syndrome- characterized by the development of numerous defects in the fetus with the onset of mental retardation in the future.

How is first trimester screening done?

Screening during pregnancy in the 1st trimester is carried out in a strict time frame. The woman is informed in advance of the time of its holding. At the appointed time, she comes to the consultation and first undergoes an ultrasound scan. This study can be carried out transvaginally (through the vagina) or transabdominally (through the anterior abdominal wall). In general, the procedure for the patient does not differ from conventional ultrasound. After receiving the results, if a pathology is suspected, a biochemical blood test is prescribed. The material is taken from a vein, on an empty stomach in the morning.

First screening during pregnancy - timing

To set themselves up, to prepare in advance for the study, women often ask doctors when they do screening for the 1st trimester. The timing of this examination is very limited - in order to obtain objective results, it must be carried out strictly at certain times of pregnancy. The optimal period for a screening study is from the first day of the 10th week of pregnancy to the 6th day of the 13th week. In most cases, the first screening during pregnancy, the terms of which are mentioned above, is carried out at 11–12 weeks of gestation. At this time, the error in the calculations is minimal.

Preparing for 1st trimester screening

In order for the screening of the first trimester to be objective, doctors insist on following the rules for preparing for the study. In the case of ultrasound, everything is simple: if it is carried out with a transvaginal sensor, then special preparation is not required; if through the anterior abdominal wall - it is required to fill the bladder before the ultrasound procedure.

Preparation for a biochemical blood test is more complex and includes:

1. Compliance with the diet: exclusion from the diet of citrus fruits, seafood, chocolate.
2. Refusal of fried and fatty foods.
3. Blood is given in the morning, on an empty stomach. The last meal should take place no later than 12 hours before the expected time of analysis.

Screening results of the 1st trimester - transcript, norm

After the screening of the 1st trimester is carried out, the interpretation of the results is carried out exclusively by the doctor. The pregnant woman is unable to objectively evaluate the obtained values, even when comparing them with the normal values. Each pregnancy has its own characteristics, so the result should be evaluated taking into account the course of gestation, its duration, the state of the female body, and the number of fetuses.

When evaluating the indicators of the individual development of the baby, obtained using ultrasound, doctors pay attention to the following parameters:

• KTP - the size of the fetus from the crown to the coccyx;
• body length - the size of the baby's body from the crown to the heels;
• Head circumference;
• BDP (biparietal size) - the distance between the dark tubercles;
• TVP - collar space thickness;
• HR is the baby's heart rate.

When conducting biochemical screening during pregnancy, two main indicators are paid attention to:

• β-hCG - chorionic gonadotropin;
• PAPP-A is pregnancy-associated protein-A.

Screening norms of the 1st trimester - ultrasound transcript, table

In each individual case, doctors, when evaluating the results of ultrasound screening of the 1st trimester, make an adjustment for the individual characteristics of the development of the fetus. Given this fact, doctors allow a slight deviation of the indicators from the established norms. In addition, the results of the studies may be influenced by another factor - the error in calculating the term carried out by the obstetrician. When conducting the first screening during pregnancy, the norms of which are shown in the table below, doctors first determine the exact gestational age.

1st trimester screening - interpretation of blood results

As noted above, a pregnant woman’s blood is used when a pathology is diagnosed or there is a suspicion of it with ultrasound. At the same time, doctors pay attention to the following indicators:

1. β-hCG- chorionic gonadotropin, a hormonal substance synthesized by the chorion. With the help of it, pregnancy is diagnosed at an early stage. However, an important indicator is it during the entire 1 trimester. Every day, the concentration of hCG increases, reaching a maximum by 11-12 weeks of gestation.
2. PAPP-A- protein-A associated with pregnancy. This protein compound is produced by the placenta, responsible for its normal development and functioning. After the biochemical screening of the 1st trimester has been carried out, the interpretation of the results is carried out by the doctor observing the pregnant woman. The values ​​of these indicators by gestational age are given in the tables below.

Gender of the baby at the first screening

Prenatal screening of the 1st trimester does not allow you to reliably determine the gender of the unborn baby. Given this fact, doctors do not attach much importance to this indicator. However, at the request of the mother herself, a specialist with a convenient location of the fetus can make his own assumptions about the sex of the fetus. In practice, they do not always coincide with reality and are often erroneous, so when the first screening is done, this parameter is not taken into account.

Perinatal fetal screening is a set of diagnostic procedures performed at certain stages of pregnancy. 1st trimester screening allows early identification possible anomalies and indirect signs of the presence of pathologies in the fetus. This study, conducted from 11 to 14 weeks of pregnancy, includes ultrasound screening and biochemical research. Respectively, 1st trimester screening transcript occurs by comparing the results of the above diagnostic measures.

Deciphering ultrasound screening

An ultrasound examination of the 1st trimester, which is mandatory for every pregnant woman, allows you to identify signs of Down syndrome and some other pathologies in the development of the fetus. Screening of the 1st trimester, the interpretation of the results of which begins precisely with the interpretation of ultrasound data, should be carried out up to 14 weeks. After this period, some indicators may already be uninformative. The screening norms of the 1st trimester, the decoding of these norms largely depend on the period of fetal development.

One of the most important indicators that is a marker of chromosomal diseases and allows to identify an increased risk of Down syndrome in the 1st trimester is TVP - the thickness of the collar space.

Norms of ultrasound TVP:

at 10 weeks of pregnancy, the thickness of the fold is normal - 1.5-2.2mm;
normal at 11 weeks 1.6-2.4mm;
indicator 12 weeks - 1.6-2.5mm:
norm 13 weeks - up to 2.7 mm.

If the thickness of the collar fold exceeds the norm, this is a direct indication for further diagnosis.

The next indicator that is measured on ultrasound in the 1st trimester is KTP, that is, the coccygeal-parietal size. KTR should normally correspond to the following results:

10 weeks - 33-49mm;
11 weeks - 42-58 mm;
12 weeks - 51-73 mm.

Deciphering ultrasound screening of the 1st trimester necessarily includes an assessment of another important indicator - the nasal bone. This marker, along with TVP, suggests that the child has Down syndrome. The nasal bone at 10-11 weeks should be detected, but at this time its dimensions are not yet estimated. At 12-13 weeks, the nasal bone should normally be at least 3 mm according to the results of ultrasound. During ultrasound diagnostics, the doctor also measures the heart rate, which should decrease slightly with the development of the fetus. So, if at 10 weeks the norm is 161-179 beats / minute, then at 13 weeks it is already 147-171 beats / minute.

The first screening ultrasound, performed in the 1st trimester, also evaluates biparietal size (BPD). This indicator, depending on the period, should be:

at 10 weeks pregnant - approx. 14 mm;
at 11 weeks approx. 17 mm;
at 12 weeks - approx. 20 mm;
at 13 weeks - 26 mm.

Having deciphered the results of the first demonstrative ultrasound, the doctor makes a conclusion about the presence (absence) of markers of various pathologies, and also determines what period at the time of the study corresponds to the development of the baby.

Deciphering biochemical screening

Biochemical research in the first trimester ("double test") is carried out in order to identify the risk of chromosomal abnormalities, namely Edwards and Down syndromes.

This screening involves the determination in the blood of a pregnant woman of specific markers that indicate the presence of certain pathologies in the child. These biochemical blood tests do not accurately diagnose chromosomal abnormalities in the fetus, however, deviations from the norm can reveal an increased risk of pathology.

Biochemical screening of the 1st trimester includes two studies:

determination of the presence in the blood of a pregnant woman of chorionic gonadotropin (β-hCG)

plasma protein A (PAPP-A) study

The norm of the free β-subunit of the hCG hormone in the first trimester is either 0.5–2 MoM, or (if measured in ng / ml) varies from 25.8 to 181.6 ng / ml at 10 weeks and gradually decreases by week 14 to 14, 2 - 114.7 ng / ml.

When biochemical perinatal screening of the 1st trimester is carried out, the interpretation of the results of β-hCG occurs as follows. If this marker is higher than normal, the child is diagnosed with an increased risk of Down syndrome. And, conversely, if the indicator is below the norm, there is reason to assume the presence of Edwards syndrome.

The second important indicator of PAPP-A, studied in the screening of the first trimester, may also indicate diseases of the unborn baby.

If the screening transcript found that PAPP-A is not normal, then the unborn child may also have Down syndrome or Edwards syndrome.

Once again, it should be noted that the likelihood of various pathologies in the development of the fetus should be assessed by the doctor on the basis of all the studies carried out in the complex. Deviation from the norm of only one indicator is not always an alarming signal. So, if the PAPP-A indicator is higher than the required standards, but the other indicators of the screening performed do not have deviations, then the risk of chromosomal diseases in the unborn baby is not high.

Risk calculation

To calculate the risks of pathological abnormalities in the 1st trimester, the results of all studies conducted during the screening process, including the results of ultrasound, are required. The calculation is carried out using a special computer program that takes into account not only the results obtained, but the age and individual characteristics of the pregnant woman. The program gives the most accurate result, since it takes into account many factors in a complex way.

For a correct calculation of the risk of fetal anomalies, it is necessary that biochemical analyzes be taken in the same laboratory that performs computer calculation of the result. This is due to the peculiarities of the program, tuned to the individual standards and parameters of each laboratory.

The result of the computer risk calculation is written as a fraction, for example, 1:10, 1:300, 1:1000 or another ratio. This fraction shows the degree of risk of having a child with a pathology. Yes, the risk 1:200 means that at these screening rates, out of 200 children, 1 child has Down syndrome.

Further, on the basis of the received fraction, the final conclusion is made. If the test is positive, this indicates a high risk of anomalies and the need for additional research. Negative test on the contrary, indicates a low risk.

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Let's discuss?

Now I have begun to take an active interest in everything related to pregnancy (the biological clock is ticking, it's time to become a mother), and first of all I was interested in what kind of tests I need to take in order to find out about the pathology of the fetus. At first I doubted whether it was worth it, were the results so accurate? But after reading the article, I realized that now the possibility of determining fetal pathologies using ultrasound and biochemical screening is very high, almost 100%. Moreover, everything is described so clearly here that the results of the analysis can be read by yourself. I really believe that I will be all right.

Very interesting and informative article. And I am expecting a child, the term is still very short, but I am very worried about the issues of congenital anomalies of the fetus. It seems to me that the doctors will not tell the truth, they will deceive, and I will not find out that something is wrong with my child, and in general that all these ultrasounds and tests can harm my baby. But here I received exhaustive answers to all the questions that torment me. It turns out that it is very important not to miss the moment and do everything on time, especially since the veracity of the results is almost one hundred percent. I'm almost a doctor myself, thanks to articles like this. I believe that everything will be fine. And nobody can deceive me. I bookmarked it, I'll take a look later.

In the first trimester of her pregnancy, every woman undergoes such a painless procedure as screening. For many, this is a new concept. Therefore, there is a need to consider in more detail the issue of screening and identifying the main pathologies based on its results.

This procedure is very important during gestation, as it provides information about condition and development of the child. It is carried out in order to exclude any pathological changes in the body of the fetus of a genetic nature.

Screening consists of a blood test and. Before screening, the specialist takes into account the main characteristics of the pregnant woman (height, addiction to bad habits, possible diseases) that may affect the results of the examination.

Thanks to ultrasound, the specialist examines how the physique of the child develops, and are there any obvious deviations. If there is a suspicion of a pathology, then the future woman in labor is sent for a detailed diagnosis with subsequent treatment.

the expectant mother can find out how well the fetus is developing, and whether it has any genetic ailments. If the fetus develops with signs of Down's disease, then this will be determined due to the thickness of the collar space. Pathologies are detected by special indicators when blood test:

1. : if the figure is below the norm, then, most likely, the fetus will have Edwards syndrome, if it is higher, Down syndrome.
2. PAPP-A indicator(plasma protein) : a value less than the norm indicates that in the future the child is prone to diseases.

Ultrasound at the first screening aims to determine the following points:

• the location of the fetus to exclude the possibility of an ectopic pregnancy;
• confirmation of singleton or multiple pregnancy;
• tracking the heartbeat and viability of the embryo at the tenth week of development;
• calculation of KTR (coccyx-parietal size);
• anatomical examination of the fetus (both external defects and pathologies of internal organs are determined);
• examination of the collar space, the thickness of which, during normal development, should correspond to two centimeters. If thickening is noted, then the probability of a defect is high;
• examination of the state of the placenta and the exclusion of its dysfunction.

It is this comprehensive study that helps identify genetic and chromosomal disorders of the fetus. If a serious diagnosis is confirmed, crippling the life of the unborn child, then the pregnant woman may offer artificial termination of pregnancy.

Only according to complex analyzes, the doctor determines the exact condition of the fetus. If the probability of pathology is confirmed, the woman is sent for special tests - biopsy and amniocentesis. Based on the results of which, final conclusions are made and a decision is made about the future fate of the fetus.

When is the first pregnancy screening done?

How many weeks of pregnancy do screenings take place? A standard pregnant woman can be screened for 10-13 weeks. But most often, based on the individual characteristics of the pregnant woman, the leading doctor himself determines exact time when to do the first screening.

When the expectant mother becomes registered, a set of studies that make it possible to monitor the condition of the pregnant woman and her fetus are mandatory. Screening can also be included here, which makes it possible for a woman in labor to be calm about the genetic and chromosomal development of the baby. But, if the woman herself refuses this procedure, then the doctor cannot force her to do the first screening.

First of all, gynecologists are guided by the interest of the pregnant woman. Since every mother should worry about the condition of the fetus from the moment of conception. The danger of not screening may be that the fetus may have a severe brain disorder early in life, leading to either death before birth or severe disability later on. Even if the pregnancy is planned and both parents are completely healthy, and there are no people with genetic diseases among the relatives, the leading doctor will still highly recommends screening.

There are risk groups who are required to be screened in the first trimester. They are not allowed to ignore the first screening. This group includes:

• women in labor over the age of 35;
• young individuals who decide to become mothers before adulthood;
• girls among whose relatives there are people with Down's disease or other ailments of a genetic nature, also if there are such representatives among the husband's relatives;
• if previous pregnancies were with fetal pathology or;
• pregnant women who abused alcohol or drugs before conception;
• if the father of the child is a distant relative of the mother in labor;
• pregnant women who have previously had cases of stillbirth;
• girls who use shortly before conception drugs for rapid termination of pregnancy;
• if the previous child was born with a genetic pathology.

A gynecologist must prescribe screening for pregnant women who had viral diseases in the first trimester. This is explained by the fact that contraindicated groups of antiviral drugs that affect the health of the fetus are used for treatment.

How to Prepare for Your First Pregnancy Screening

Preparatory activities are carried out in the antenatal clinic with the participation of a leading gynecologist. A conversation should take place between the pregnant woman and the doctor, during which the patient will find out all the questions of interest about the tests. There are also some nuances about the first screening:

1. Comprehensive analyzes should take place on the same day, and it is recommended that they be taken in the same laboratory. A woman in labor should be calm and understand that all procedures will not bring pain, if venous blood sampling is not taken into account.
2. Before donating blood, it is recommended refrain from intimacy and eating as this may affect the results.
3. Before screening, the pregnant woman should weigh herself, as accurate height and weight data at the time of the procedure will be required.
4. Immediately before the procedure, you should refrain from drinking liquids. With strong thirst, no more than one hundred milliliters of liquid is allowed.
5. The results of studies and conclusions about the presence of pathologies after decoding are reported by the doctor.

Norms of the first screening during pregnancy

If a pregnant woman knows the normal indicators, then it will be easy for her to decipher the results of the first screening on her own. Thus, future mom will already be aware of the likelihood of the risk of pathologies. For this, standards approved by specialists are provided.

Important is the protein indicators (PAPP-A), which is responsible for the normal functioning of the placenta and hCG.

These indicators are the norm and do not predict the development of defects.

Norms of indicators of the first ultrasound screening during pregnancy

The first thing the doctor pays attention to is heart rate(at this time it should be within 150-175 strokes) and KTR(not less than 45 mm.) at this time.

According to the first screening, the symmetry of the cerebral hemispheres is determined, as well as general indicators of how internal organs fetus. But, the main task of research is to provide data that confirm the likelihood of chromosomal pathology. When carrying a child, it is very important exclude in the future such deviations and diseases:

1. Triplodia (during the normal development of the fetus, a double set of chromosomes is noted).
2. Pathological changes in the neural tube.
3. Possible umbilical hernia.
4. The likelihood of developing Down syndrome.
5. Predisposition to Patau's syndrome.
6. Signs of de Lange's syndrome.
7. The fetus develops with Edwards syndrome.

Therefore, in order to start timely treatment or stimulate the development of the fetus, it is recommended that all future women in labor after the tenth week go for screening. Deciphering 1 screening during pregnancy should be done by a specialist, because. incorrect interpretation of the parameters will only lead to unwanted panic and anxiety.

Factors affecting the results of the first screening

Sometimes the results of a complex studies may be inaccurate, and the following factors accompany this:

• overweight pregnant, stage of obesity;
• if conception did not occur naturally, but with the help of IVF, then the protein levels in the blood will be underestimated;
• if the pregnancy is multiple (in this case it will be difficult to determine the rate of the norm);
• experiences and stressful situations on the eve of the test for the expectant mother;
• amneocentosis may also affect the results;
• if a pregnant woman is diagnosed.

Such cases distort the results of screening and do not give a complete clinical picture of the condition of the unborn baby.

As you know, there can be various factors that will significantly affect the results of research. Shouldn't be ruled out likelihood of medical error. So, false results that are easily confused with indicators of a genetic disease are present:

• in pregnant women with diabetes mellitus;
• also a deviation from the norm of hCG can be when a woman is pregnant with twins;
• delayed first screening (sooner or later);

Video of the first screening

We invite you to watch the video about the first screening, where you will hopefully find answers to your remaining questions.

To exclude possible unpleasant outcomes of pregnancy, it is strongly recommended that every pregnant woman be examined through screening in the early stages. It is thanks to this method that most of the syndromes are detected. How was your first screening?