Screening of the 1st trimester, which shows a blood test. The timing of the first screening during pregnancy. Screening Ultrasound

For many girls, just the phrase about screening the first trimester already causes excitement.

Meanwhile, prenatal fetal screening implies an absolutely painless comprehensive examination.

When they spend

The first is carried out initially in the 1st trimester of pregnancy, that is, on -.

Screening of the first trimester allows you to determine the likelihood of having a baby with congenital malformations of its development (CMD).

What it is

Prenatal ultrasound screening of the fetus is a set of specific diagnostic measures for a pregnant woman.

Screening methods are called studies that can be used for a large survey, because they are safe and easy to perform.

The results show possible gross anomalies in the development of the fetus and indirect signs of pathologies.

Perinatal fetal screening includes:

1. Special ultrasound screening
   • traditional ultrasound examination (everyone usually calls it) of the fetus throughout pregnancy. How this procedure is carried out, you can see in the photo and video.
   • If you are interested in how much it costs, then know that in each clinic the prices for ultrasound are different. For example, in Invitro, a study costs about 1,500 rubles.
2. Biochemical screening.
   • It is aimed directly at identifying the risks of developing syndromes such as Edwards or Down syndrome.

The study involves the determination of certain specific substances in the blood (the so-called "markers") - they always change in the presence of certain pathologies.

Fetal biochemistry during the first trimester does not make it possible to make an accurate diagnosis.

The results of the survey only to some extent allow us to identify women with a slightly high risk of any pathology.

And in order to make a more accurate diagnosis, it is necessary to conduct additional examinations (invasive diagnostics, ultrasound).

What is examined in the first trimester

Biochemical analysis involves donating blood, which is examined in the laboratory for the presence of β-hCG - the so-called human chorionic hormone.

Also in the blood, plasma protein A (denoted by PAPP) associated directly with pregnancy, and AFP (decoding alpha-fetoprotein) are examined.

The results of the 1st trimester screening are usually sent to the attending physician from the laboratory, and he is already evaluating the data received.

Based on whether a poor analysis, or the results are normal, the doctor gives the pregnant woman further recommendations. Refers to a combined or assigns a more detailed diagnosis to a woman.

When calculating the risk of pathology, or vice versa, the norms find out the weight, age, possible hereditary ailments of a pregnant woman, mother's illness, her bad habits. Results (indicators) also depend on all this.

The results and norms of research are evaluated in modern laboratories, using an automated special program called Prisca. What it is?

Prisca is a computer program. It is Priska who evaluates, in accordance with the results of the analysis, the individual probability of various chromosomal diseases, as well as other possible congenital anomalies of the unborn child.

The optimal time for screening is 11-13 weeks of pregnancy.

Biochemical screening of the fetus during the first trimester of pregnancy (the so-called "double test") includes the following studies:

• Free b-subunit of human chorionic gonadotropin (or simply free β-hCG).
• The plasma protein A that is associated with pregnancy is PAPP-A.

However, in order to calculate the risk of trisomy and determine the norms using the Prisca program, ultrasound results are needed.

That is, in order to determine the indicators of the norm and risks, the doctor will definitely need ultrasound data, which was carried out in the 1st trimester, namely, KTR (coccygeal-parietal size) or ultrasound KTR + TVP (survey results (video / photo) with the thickness of the collar space).

Indications for biochemical analysis

This examination during the first trimester is necessarily done with such indications:

• When a woman has her first pregnancy after 30 years.
• If you have had several miscarriages before.
• If the expectant mother has hereditary pathologies.
• If a woman already has children with some kind of genetic type pathologies.
• When deviations from the norm / risks are found during the ultrasound of the first trimester.
• With severe pathologies during pregnancy, which confirmed the results of ultrasound.
• If a woman works in a hazardous industry.
• If the marriage is closely related.
• If at the beginning of pregnancy a woman has been ill with viral diseases.

Tests for diseases that are directly transmitted sexually are also carried out in the 1st trimester, since they can cause very serious pathologies during the further development of the fetus.

A blood test allows you to:

• detect signs/presence of rubella, as well as viral hepatitis B.
• assess the level of certain hormones of a woman during pregnancy.
• a thorough study of the total level of glucose in the blood during the entire period of pregnancy allows the doctor to monitor certain blood parameters that are responsible for gestational diabetes mellitus and prescribe treatment in time.

In turn, an elevated protein level in the blood may indicate the presence of any pathology of the urinary system, kidneys, and even the development of preeclampsia.

How many of these tests you need to take, the attending physician determines, depending on what results the first analysis gave.

Deciphering the norm

1. The norms of pregnancy-associated plasma protein A are from 0.46 to 8.54 MIU / ml. If the analysis gave a result below the norm, this indicates a threat of miscarriage, Down syndrome, as well as Edwards syndrome.
2. Analysis for the beta subunit of human gonadotropin (chorionic). Normal - 20000 - 60000 IU / l.

A bad result is any deviation from the norm.

This type of examination is prescribed for women who are diagnosed with 11-13 weeks of pregnancy. The initial stage of the first screening during pregnancy is an ultrasound examination. After that, the pregnant woman is sent for a biochemical blood test.

Such events make it possible to identify genetic defects, pathologies in the structure of the embryo and respond to them in a timely manner.

How to prepare for the first screening?

The procedure under consideration includes two types of examination, each of which needs a certain preparation.

ultrasound

Can be done in two ways:

1. External (abdominal). It is given with a full bladder, therefore, 30-60 minutes before the start of the procedure, the pregnant woman must drink at least half a liter of purified water without gas, or not urinate 3-4 hours before the start of the ultrasound.
2. Vaginal. This type of examination does not require special preparation. Some clinics require patients to come to the appointment with their own diaper, sterile gloves and a condom for the ultrasound transducer. All this can be purchased at almost any pharmacy.

(double test)

It provides for the following preparatory measures, ignoring which can significantly affect the test results:

• 2-3 days before the analysis, a pregnant woman should refrain from fatty, salty foods (meat, seafood), citrus fruits and chocolate. The same goes for multivitamins.
• Blood must be donated on an empty stomach. The last meal should be at least 4 hours before the test.
• Doctors also advise to exclude sexual intercourse a couple of days before the screening.

How does the first screening in pregnant women go and what does it show?

The specified type of examination must begin with. After all, it is ultrasound diagnostics that makes it possible to determine the exact gestational age - and this very important for the second stage of screening: the double test. After all, the indicators of the blood norm, for example, for 11 and 13 weeks will be different.

In addition, if an ultrasound scan detects the fetal fading or the presence of serious anomalies in it, there will be no need for a biochemical blood test.

Thus, at the time of passing the second stage of the first screening, the pregnant woman should have the conclusion of an ultrasound doctor in her hands.

Ultrasonography

The type of examination under consideration favors the identification of such physical defects of the fetus:

• developmental delay.
• The presence of serious pathologies.

Also thanks to ultrasound the gestational age is determined, the number of fetuses in the uterus, the approximate date of birth is set.

In the first third of pregnancy, the following indicators are checked on an ultrasound machine:

1. The distance from the coccyx to the parietal part of the head. This parameter is also called the coccygeal-parietal size (KTR). At the 11th week of pregnancy, the CTE varies within 42-50 mm, at the 12th week - 51-59 mm, at the 13th - 62-73 mm.
2. The size of the nasal bone. At the 11th week, it is not visualized. At 12-13 weeks, its parameters are more than 3 mm.
3. The distance between the tubercles of the parietal region, or biparietal size (BDP). Normally, this indicator should be 17 mm at the 11th week; 20 mm at 12 weeks; 26 mm at the 13th week of pregnancy.
4. Embryo head circumference.
5. The distance from the forehead to the back of the head.
6. The structure of the brain, symmetry and size of its hemispheres, the quality of the closed skull.
7. Heart rate (HR). By means of this parameter, cardiac arrhythmia can be detected. When measuring the heart rate, the sonographer must be very careful: due to the short duration of pregnancy, it is possible to confuse the pulsation of the patient's vessels with the heartbeat of the embryo. Normally, the indicator in question varies between: 153-177 at the 11th week of pregnancy; 150-174 - at the 12th week; 147-171 - on the 13th.
8. Parameters of the heart and its arteries.
9. The structure of the femur, shoulder, tibia.
10. The distance between the inner and outer surface of the skin of the neck, or the thickness of the collar space (TVP). Normally, this indicator will be: at the 11th week of pregnancy 1.6-2.4 mm; at the 12th week - 1.6-2.5 mm; at the 13th week - 1.7-2.7 mm.
11. The structure of the chorion (placenta), its location. Upon detection of exfoliation of the chorion, its volumes are established and whether there is a tendency to progress. A similar phenomenon can provoke spotting and complaints of a pregnant woman about pain.
12. Shape and size of the yolk sac, the quality of supply of the umbilical cord with vessels. The yolk sac normally decreases in size by the 12th week of pregnancy, and at the time of ultrasound diagnosis, it should be a tiny (4-6 mm) cystic neoplasm of a rounded shape.
13. The structure of the uterus, its appendages. Particular attention is paid to the ovaries: in the later stages of pregnancy, it is problematic to examine them.

At the time of the first screening ultrasound the fetus must be positioned correctly so that the specialist can carry out a qualitative inspection and make the necessary measurements.

If the child is not positioned correctly, the patient is asked to roll over from her back to her side, cough, or squat.

Double test (norms and interpretation)

For this type of examination, blood is used from a vein, which is taken on an empty stomach.

Biochemical screening is needed to determine the following parameters:

1.Protein Pregnancy (PAAP) -A )

This protein is produced by the placenta and increases with the course of pregnancy.

Normally, the indicators of this protein will be as follows:

• 11-12 weeks: 0.77-4.76 honey / ml.
• 12-13 weeks: 1.04-6.01 mU / ml.
• 13-14 weeks: 1.48-8.54 mU / ml.

A reduced amount of PAAP-A may be due to the following deviations:

1. There is a threat of miscarriage.
2. The developing embryo has Down syndrome, Edwards syndrome, or another genetic disease.

An increase in the level of PAAP-P in the blood of a future mother often does not have an important diagnostic value.

2. Amounts of human chorionic gonadotropin (hCG)

This hormone is produced in the first weeks of pregnancy, reaching a maximum level at the 12th week of pregnancy, after which the amount of the hormone in question decreases.

By studying the indicators of the amount of hCG in the blood of a pregnant woman, it is possible to determine the presence / absence of chromosomal abnormalities.

In the conclusion sheet, this parameter is written in the column “free β-hCG”.

In the first trimester of pregnancy, the norm of this hormone is as follows:

• 11th week: 17.3-130.2 ng / ml.
• 12th week: 13.3-128.4 ng / ml.
• 13th week: 14.3-114.7 ng / ml.

Elevated levels of hCG may indicate several phenomena:

• A developing fetus has Down syndrome.
• The mother-to-be has diabetes.
• The pregnant woman suffers from severe toxicosis.

A decrease in the level of the hormone in question may occur against the background of the following factors:

• There is a risk of miscarriage.
• Pregnancy formed outside the uterine cavity
• Failure of the placenta to perform its basic functions.
• The fetus has Edwards syndrome.

What pathologies can be detected on the screening of the first trimester?

In the first three months of pregnancy, through examinations, it is possible to identify or suspect the presence of the following ailments:

• Errors in the structure of the neural tube (meningocele).
• Down Syndrome. The prevalence of this disease: 1:700. Timely detection of this pathology made it possible to reduce the birth rate of sick babies (1 per 1100 cases).
• Umbilical hernia (omphalocele). Ultrasound examination shows that the internal organs are in the hernial sac, and not in the abdominal cavity.
• Edwards syndrome (1:7000). It is characterized by a reduced heart rate, omphalocele, insufficient number of blood vessels on the umbilical cord, absence (inability to visualize) the nasal bone. Pregnant women over 35 years of age are at risk.
• triploidy. With this pathology, instead of 46, there are 69 chromosomes in a fertilized egg. Such a phenomenon may occur due to an incorrect structure of the egg, or when two spermatozoa penetrate one egg. Often, with such anomalies, women do not bear a fetus, or give birth to dead children. In those rare cases when it was possible to give birth to a live baby, the period of his life is limited to a few days / weeks.
• Patau disease (1:10000). Ultrasound ascertains retardation in the structure of the brain, tubular bones, increased heart rate, omphalocele. Often, babies that are born with a similar diagnosis live a maximum of a couple of months.
• Smith-Lemli-Opitz syndrome (1:30000). It is the result of genetic disorders, due to which the qualitative assimilation of cholesterol is impossible. The pathology under consideration is capable of provoking many malformations in development, the most serious of which are errors in the functioning of the brain and internal organs.

To confirm some of the above pathologies, it is required additional diagnostic measures, and in most cases they are invasive.

What can affect the results, and can the doctor make a mistake at the first screening?

Screening for the first trimester of pregnancy has certain disadvantages.

On the other hand, it is still necessary to conduct an examination: timely detection of a particular pathology will make it possible to terminate the pregnancy (if the fetus is with severe abnormalities), or take measures to maintain the pregnancy (if there is a threat).

In any case, it will be useful for any expectant mother to know that false positive screening results can occur in the following situations:

1. ECO. With artificial insemination, the parameters of the occipital part of the embryo will be 10-15% higher than normal. A double test will show an increased amount of hCG, and a low level (up to 20%) of PAAP-A.
2. Weight of the expectant mother: severe thinness is a consequence of a decrease in the amount of hormones, and with obesity, the opposite phenomenon is observed.

What week is screening done during the 1st trimester to get the most information about the baby?

Expectant mothers in vain rush to go for an examination as soon as they find out about their interesting situation. The 1st screening, consisting of a blood test and an ultrasound, is pointless to take place early.

But it cannot be postponed either, because this mandatory procedure evaluates the processes of intrauterine development.

In the first three months of pregnancy, it is necessary to undergo screening in order to detect serious pathologies without delay.

These include an anomaly of the rudiment of the future nervous system, Patau's syndrome, a hernia of the umbilical cord (the intestines and liver are located outside the abdominal cavity - in the hernial sac), trisomy on the 21st (Down syndrome) or 18th chromosome (Edwards syndrome).

On ultrasound during the 1st trimester, the growth of the embryo is measured, determining its coccyx-parietal size, circumference and biparietal size of the head.

At the first screening, you can see if the right and left hemispheres are symmetrical relative to each other. At this time, the doctor will be able to see what structures have appeared in the brain.

The first screening involves measuring the length of the four main bones: thigh, lower leg, upper arm, and forearm.

The doctor checks where the internal organs (heart and stomach) are located, determines the size of the heart muscle and the veins and arteries coming from it.

Also on ultrasound in the first three months of pregnancy, the abdominal circumference of the embryo is measured.

Biochemical screening is aimed at determining plasma protein A and human chorionic gonadotropin.

Thanks to this study, the doctor learns about the presence of chromosomal abnormalities, about the possible risks and complications of pregnancy.

In the first trimester, the study should in no case be skipped by women who are married to a close relative, and those who have had several miscarriages.

The first screening is a very important procedure for women who have had a viral or bacterial infection in the position.

Women who have:

• previously had a frozen pregnancy;
• have relatives with genetic abnormalities;
• a child with Down syndrome or Edwards syndrome has already been born;
• age has reached the age of 35;
• was therapeutic therapy with drugs prohibited during pregnancy.

In any case, it is impossible to forget about visiting an uzist doctor, because every parent needs to make sure that the child is healthy.

Timeframes and features

The expectant mother can go for an ultrasound of the fetus and donate blood for analysis at the 10th week of pregnancy. But doctors urge to do this a little later - between 11 and 13 weeks.

It is at this time that it is possible to perform accurate measurements of the level of hormones and the collar zone of the fetus.

The deadline for examining the internal organs and limbs of the child at the 1st screening is the 14th week of pregnancy.

It is better to come for an ultrasound at least at this time than even later, because doctors need to determine the time of birth and the degree of development of the child in time by its coccyx-parietal size.

The first examination for the expectant mother will begin with an ultrasound. There is no need to prepare for a transvaginal examination, but for a transabdominal ultrasound, you will have to drink a large amount of water (1 liter).

Filling the bladder before examination at 10-14 weeks is a prerequisite, otherwise the ultrasound will not pass through the abdominal wall.

Transabdominal ultrasound is done through the abdominal wall. A woman needs to lie down for some time, exposing her stomach and inguinal region.

The doctor will guide the skin with a special sensor treated with a gel to improve gliding.

To conduct a transvaginal study at 10 - 14 weeks of pregnancy, a woman must completely free herself from clothes below the waist, lie down and bend her legs.

The doctor will insert a thin probe into the vagina, on which a special condom will be put on, and evaluate the development of the fetus in the uterus.

This will not cause pain, but, perhaps, after the procedure, spotting spotting will be observed.

The next time, for the second screening, preparation is not required, because the ultrasound will help to penetrate the accumulated amniotic fluid.

You will always have to prepare for blood sampling to determine the ratio of hormones. A few days before the analysis at 10-14 weeks, the pregnant woman must give up sweets, meat and fish.

Usually, blood is taken from a vein in the morning. You can't eat breakfast right before. You can eat the last meal 4 hours before the procedure.

Ultrasound indicators in the 1st trimester

After an ultrasound of the first trimester, a woman wants to understand the information written in the examination protocol.

After all, the mothers themselves do not know how much the coccyx-parietal and biparietal dimensions, the thickness of the collar space and the heart rate should be.

The thickness of the collar space (TVP) at the 10th week of pregnancy is normally 1.5 - 2.2 mm. At 11 and 12 weeks, this figure increases to at least 1.6 mm.

At the 13th week of the 1st trimester, it is already 1.7 - 2.7 mm. If the value of TVP is higher than the established norm, then the child may have genetic abnormalities.

To determine the BDP indicator, you need to know exactly how many days have passed since the day the child was conceived.

It is important to assess the thickness of the collar space during the first trimester, since then the measurement of this indicator will not be available.

For a period of 10-11 weeks, the nasal bone should be clearly visualized on the screen of the ultrasound equipment. A little later, the doctor already has the opportunity to measure it. The normal size of the nasal bone is from 3 mm. This indicator is noted in almost 100% of embryos.

When the first screening is done, it is determined how many times per minute the baby's heart beats. At week 10, the organ of the embryo should make more than 161 beats per minute.

The limit is 179 hits. A week later, the baby's heart should beat less frequently, between 153 and 177 beats per minute.

The normal rate for the 12th week is 150 - 174 bpm, and for the 13th - 147 - 171 bpm.

Too frequent heartbeat of the child may indicate the presence of an anomaly of the 21st pair of chromosomes, that is, Down syndrome.

During the first screening, the doctor necessarily determines the size of the maxillary bone in the embryo. If this indicator is less than normal, the child should be suspected of a genetic disease - trisomy.

Later than the 11th week of pregnancy, it becomes possible to examine the bladder of the fetus. An enlarged organ is a clear sign of a child with Down syndrome.

1st trimester blood test results

Biochemical screening in the first three months of pregnancy reveals how much hCG and PAPP-A are contained in the blood serum. But the most informative than hCG is the indicator of β-hCG.

The fact is that the level of hCG can change not only because of the woman's pregnancy. Sometimes hormonal imbalances and the use of certain medications can affect its value.

The level of β-hCG depends solely on the duration of the woman's pregnancy. At week 10, its value should fluctuate between 25.8 and 181.6 ng / ml, at week 11 - between 17.4 and 130.4 ng / ml.

Within 12 weeks, this indicator is normally 13.4 - 128.5 ng / ml. When the 13th week of pregnancy ends, the level of β-hCG can reach 14.2 - 114.7 ng / ml.

The value of β-hCG may indicate not only the presence of deviations in the genome in the fetus, but also the incorrect course of pregnancy and the deterioration of the woman's condition.

If biochemical screening showed that a woman has an elevated hormone level, then this may indicate:

• multiple pregnancy;
• acute toxicosis;
• down syndrome;
• diabetes mellitus;
• blistering.

Also, the reason may be in taking certain drugs and the presence of cancer in a pregnant woman.

Low levels of β-hCG signal other problems:

• Edwards syndrome in the fetus;
• pregnancy in the fallopian tube;
• frozen pregnancy;
• risk of spontaneous abortion.

During the 1st trimester in a woman, it is very important to determine the level of PAPP protein. It is produced by the placenta and gradually increases throughout pregnancy.

When there is a low level of PAPP-A, the doctor suspects chromosomal abnormalities in the fetus. The most common are Down syndrome and Edwards syndrome.

But, if the screening showed a very high level of PAPP-A, then the pregnancy is frozen or it may terminate unexpectedly.

It is better to determine the level of PAPP-A before the 14th week. It is not advisable to do this later, since then it will not be possible to identify Down syndrome by the content of this protein.

In order to find out important data about the process of intrauterine development of a child in time, take into account all the risks and identify anomalies, it is necessary to do an ultrasound scan and a blood test on time.

According to the rules, a woman must undergo all examinations of the first trimester in the period from 10 to 14 weeks.

The first screening or screening of the first trimester involves a comprehensive examination, which is carried out by taking blood from a vein and performing an ultrasound for a period of 11-14 weeks. It allows you to determine the risk of pathological changes in the fetus, and, above all, is aimed at identifying malformations of the neural tube, Down syndrome and Edwards syndrome, gross violations in the development of other organs and systems.

In Russia, screening has been carried out relatively recently, since 2000. Over this period, the birth rate of children with pathologies such as Down syndrome has significantly decreased: if earlier it was 1 in 600 newborns, now it is 1 in 1100; Edwards syndrome: they are detected in every 400 pregnant women (often such a pregnancy is terminated on its own, so the frequency of having a child with Edwards syndrome is 1 in 6500 (that is, out of 6500 women, 1 will be born child with trisomy 18).

The first screening does not detect a specific disease in the fetus, but indicates typical markers for it, if any. Based on its results, without additional studies, a diagnosis during pregnancy is not made. Doctors may only have suspicions that will need to be confirmed or refuted using invasive laboratory techniques. This procedure must be prescribed to women who are at risk.

Who is screening

• women whose age at the time of pregnancy is 35 years or older
• women who have hereditary diseases
• women who have had viral diseases during early pregnancy;
• if previous pregnancies ended in fetal fading, stillbirth
• if the baby is from a consanguineous marriage
• if the expectant mother uses drugs or medications prohibited during pregnancy;
• if the mother is alcoholic
• if the first children with genetic abnormalities;
• if the future mother has harmful working conditions;
• if there were miscarriages, termination of pregnancy in the past.

The first screening can also be carried out if the couple themselves express a desire to make sure that everything is in order with their child. The procedure involves 2 pregnancy studies - ultrasound and a blood test (in this case, it is taken from a vein).

When is the first pregnancy screening done?

The first screening (first trimester screening) is carried out for a period of 11-14 weeks, with the ideal period being 12-13 weeks. To be more precise, starting from the first day of week 10 and ending on the fifth day of the 13th. The most optimal time for conducting the first screening studies is the middle of the indicated time, i.e. approximately the sixth day of the 11th week. More accurately, the date is calculated by the doctor who prescribes the tests and conducts the pregnancy. In some cases, the first screening period may be slightly extended to the 6th day of the 14th week, but then the error in the data obtained will be more noticeable, and the results will not be entirely accurate.

What research is being done

First trimester screening includes:

• ultrasound examination (moreover, many laboratories request ultrasound results without fail, calculations are not carried out without them)
• biochemical study (blood test). Two hormones are being studied: the free b-subunit of human chorionic gonadotropin (free b-hCG) and PAPP-A (plasma protein A associated with pregnancy)

What is determined by the results of research

ultrasound examination:

• the physique of the baby: are all the parts in place, are they located correctly;
• Head circumference;
• the length of the lower leg, forearm, shoulder, femur, tubular bones;
• the growth of the embryo, which must comply with the norms;
• the rate of fetal blood flow, the work and size of the heart;
• volume of water;
• symmetry of the cerebral hemispheres and their structure;
• KTR (this is how the coccyx-parietal size is designated);
• LZR (read as fronto-occipital size);
• TVP (this is the thickness of the collar space);
• HR (heart rate);
• BPR (stands for biparietal size) - the gap between the parietal tubercles;
• structure, location, size of the placenta;
• the number of umbilical vessels;
• condition of the uterine cervix;
• her hypertonicity

Blood chemistry:

• plasma protein level (referred to as PAPP-A);
• the content of human chorionic gonadotropin (in the conclusion there should be a column "free β-hCG").

How to prepare for analysis

• You can not be nervous before the procedure, because experiences can affect the accuracy of the results. You have to trust that the baby is ok.
• The studies carried out as part of the first screening are absolutely painless, so there is no need to be afraid of them.
• Transvaginal ultrasound of pregnancy does not require preparation.
• With abdominal ultrasound, it is desirable that the pregnant bladder is full. To do this, a few hours before the study, you need to drink a sufficient amount of non-carbonated, clean water and not go to the toilet.
• Blood for biochemical analysis is taken on an empty stomach. Therefore, 4 hours before the analysis, you can not eat.
• 2-3 days before a double blood test, you will have to go on a diet so that the analysis gives more accurate results. You can not eat chocolate, seafood, meat, nuts, fatty and smoked foods.
• 2-3 days before the first screening, doctors recommend abstaining from sexual intercourse.

You need to mentally and physically prepare for the first screening so that its results are more accurate. For greater peace of mind, you can find out in advance what this procedure is and how it is carried out.

The first screening during pregnancy is normal:

Ultrasound examination:

Coccyx-parietal size (KTP)

• • • At 10 weeks: the norm varies from 33 to 41 mm;
    • at 11:42-50;
    • at 12:51-59;
    • at 13:62-73.

Collar space thickness (TVP)

• • • At 10 weeks: 1.5-2.2 mm;
    • at 11: 1.6 to 2.4;
    • at 12: not less than 1.6 and not more than 2.5;
    • at 13:1.7-2.7.

Heart rate (HR - beats per minute)

• • • At 10 weeks: 161-179;
    • at 11: 153 to 177;
    • at 12:150-174;
    • at 13:147-171.

nasal bone

• • • At 10 weeks: impossible to determine;
    • at 11: not measured;
    • at 12: more than 3 mm;
    • at 13: more than 3.

Biparietal size (BPR)

• • • At 10 weeks: 14 mm;
    • at 11:17;
    • at 12:20;
    • at 13:26.

Blood chemistry:

β-hCG(usually measured in honey / ml):

• • • at 10-11 weeks of pregnancy: the lower limit is 20,000, the upper limit is 95,000;
    • at 12 weeks: 20,000 to 90,000;
    • at 13-14: not less than 15,000 and not more than 60,000.

If β-hCG was measured in ng/mL, the results will be different numbers:

• • • at 10 weeks: approximate range 25.8-181.6;
    • at 11: from 17.4 to 130.3;
    • at 12: not less than 13.4 and not more than 128.5;
    • at 13: minimum 14.2, maximum 114.8.

Protein, PAPP-A(measured in honey/ml):

• • • at 10 weeks: 0.45-3.73;
    • at 11: 0.78-4.77;
    • at 12: 1.03-6.02;
    • at 13:1.47-8.55.

A blood test cannot be used to make a 100% diagnosis!

Deviations from the norm

ultrasound examination

• • • The thickness of the collar space (NTP) is the most important indicator in ultrasound to identify the risk of chromosomal pathologies.

Norms for TVP depending on the age of the embryo

If TVP exceeds the normal value, then this is a reason to suspect the presence of a chromosomal abnormality in the fetus.

To determine this indicator, it is important to know the exact gestational age (in weeks and days) and not be late with the examination, since it is impossible to determine TVP from the second trimester.

• • • Determination of the nasal bone - it is already visualized at 10-11 weeks of gestation, and at the 12th week it should be at least 3 mm. This is true for 98% of healthy embryos.
    • Fetal heart rate (HR) - depending on the weekly gestation period, normal indicators are:

An increased heart rate in the fetus is also one of the signs of the presence of Down syndrome.

• • • The spectrum of blood flow in the Arantzian (venous) duct in the fetus. The reverse flow waveform occurs in only 5% of embryos without chromosomal abnormalities.
    • The size of the maxillary bone of the fetus - its lag in size is typical for embryos with trisomy.
    • Bladder volume - at the age of 12 weeks, the bladder is determined in most healthy embryos only from the 11th week. An enlarged bladder is an additional possible sign of Down syndrome in the fetus.

If deviations in the development of the fetus are visible on ultrasound with the naked eye (absence of limbs, deformation of facial features, underestimated measurements), doctors inform parents about this and give recommendations. Most often - about the termination of pregnancy.

Blood chemistry:

β-hCG - chorionic gonadotropin. This hormone is produced by the chorion (“shell” of the fetus), thanks to this hormone, it is possible to determine the presence of pregnancy in the early stages. The level of β-hCG gradually increases in the first months of pregnancy, its maximum level is observed at 11-12 weeks of pregnancy. Then the level of β-hCG gradually decreases, remaining unchanged throughout the second half of pregnancy. regardless of the gestational age.

An elevated level of β-hCG is observed with:

• • • down syndrome
    • multiple pregnancy
    • severe toxicosis
    • maternal diabetes mellitus

A decrease in the level of β-hCG is observed in the following cases:

• • • Edwards syndrome
    • ectopic pregnancy (but this is usually established before the biochemical study)
    • placental insufficiency
    • high risk of miscarriage

PAPP-A, pregnancy-associated protein-A. This is a protein produced by the placenta in the body of a pregnant woman, is responsible for the immune response during pregnancy, and is also responsible for the normal development and functioning of the placenta.

With a decrease in its level, the risk of the following pathologies increases:

• • • Cornelia de Lange syndrome (characteristic symptoms: “bizarre face” - thick head hair for a newborn, connected eyebrows and long curved cilia, deformity of the ears and a small nose with nostrils open in front, the gap from the upper lip to the tip of the nose is abnormally large, a thin red border of the upper lip, the corners of the lips are lowered; microcephaly of the brain; brachycephaly - a decrease in the height of the skull with simultaneous an increase in its horizontal size; pathologies of the oral cavity and nasopharynx - choanal atresia, arched palate with a cleft, failures in the process of eruption of milk teeth, vision dysfunction - strabismus, disturbances in the shape of the lens, cornea, eye, myopia, optic nerve atrophy; > shortened limbs, their ectrodactyly, oligodactyly and other anomalies of the limbs; marbled skin coloring; anomalies of the nipples and genitals; hyperhairy body; episodic convulsive readiness, hypotonicity, muscle hypertonicity; dwarfism; mental retardation of varying degrees - from minor deviations from the norm (rarely) to oligophrenia and imbecility in most cases. The etiology and pathogenesis of this syndrome have not yet been established and are under study.)
    • Down syndrome
    • Edwards syndrome
    • The threat of premature termination of pregnancy

An isolated increase in the level of this protein has no clinical and diagnostic significance.

The results are in - what's next?

After receiving the results, the doctor evaluates them by calculating the MoM coefficient. - this is a special value that shows how much the result of the analysis differs from the average result for a given gestational age. It should be borne in mind that the level of hCG and PAPP-A is affected not only by the gestational age, but also by your age, weight, whether you smoke, what diseases you have, and some other factors. That is why, in order to obtain more accurate screening results, all of its data is entered into a computer program that calculates the risk of diseases in a child individually for you, taking into account all your characteristics.

Important: for a correct risk calculation, it is necessary that all analyzes be taken in the same laboratory in which the risk calculation is performed. The risk scoring program is set to specific parameters that are individual for each laboratory. Therefore, if you want to recheck the screening results in another laboratory, you will need to retake all the tests.

The program gives the result as a fraction, for example: 1:10, 1:250, 1:1000 and the like. The fraction should be understood as follows: For example, the risk is 1:300. This means that out of 300 pregnancies with rates like yours, one child is born with Down syndrome and 299 healthy children.

Depending on the fraction obtained, the laboratory issues one of the conclusions:

• • • The test is positive - a high risk of Down syndrome in a child. So, you need a more thorough examination to clarify the diagnosis. A chorionic villus biopsy or amniocentesis may be recommended for you.
    • The test is negative - a low risk of Down syndrome in a child. You will need a second trimester screening, but no additional tests are needed.

What to do if you are late for the first screening

If a woman missed the first screening, then it is possible to make a conclusion about the presence or absence of the risk of developing Down syndrome in the fetus, as well as other pathologies, during the second screening, which is carried out from the 16th to the 20th week of pregnancy. The most successful period is the entire 17th week: this will allow you to undergo additional examinations by a geneticist in case of abnormalities.