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1 screening which week obstetric. Biochemical screening. Norm. Deciphering the results. Timeframes and features

During pregnancy, a woman is carefully monitored, she regularly undergoes various examinations that help control the development of the fetus and the course of pregnancy.

The first trimester is one of the first examinations that a woman undergoes after registration. The essence of screening is to identify the likelihood of developing fetal pathologies. The results of this examination largely influence the further observation of the woman.

When and in what cases is screening prescribed during pregnancy

Screening of the first trimester is a set of diagnostic procedures that allow you to identify certain pathologies of fetal development. It is carried out for all pregnant women, without exception, at 10-14 weeks of pregnancy. The optimal time for screening is week 12, since it is during this period that the level of hormones is maximum.

The advantages of screening are its simplicity and accessibility. In fact, it includes 2 simple procedures that are carried out on the same day: and. Based on both methods of examination, the doctor makes a conclusion about the possible diseases of the child.

It is worth remembering that despite the high information content of screening, it shows precisely possible diseases and not always existing ones. So, for example, using screening, you can determine how high the risk of developing Down syndrome is, but whether this syndrome exists can be found out at a later date.

Screening of the 1st trimester, the decoding of which takes only 1-2 days, helps to identify various diseases and pathologies of the fetus in time and at an early stage.

Screening is carried out for everyone, but women should be especially attentive to the procedure and preparation in the following cases:

  • Age over 35 years. If a woman gives birth for the first time after 35 years, she is carefully examined for various genetic abnormalities. With age, the risk of genetic diseases increases.
  • A history of fertility problems. If a woman has already had miscarriages, miscarriages, premature births before her current pregnancy, special attention is paid to screening of the first trimester.
  • Women taking illegal drugs during pregnancy. A woman does not always immediately find out about pregnancy. In the earliest stages, she may unknowingly take drugs that can harm the fetus. Screening helps identify this harm.
  • The presence of hereditary diseases. If the woman herself or the father of the child has any hereditary diseases, the development of the fetus is monitored especially carefully. The presence of diseases in the next of kin of the parents is also taken into account.

Preparation and procedure

Procedures are carried out on an empty stomach. First, it is usually carried out with a full bladder. Before the examination, it is recommended to drink 2 glasses of water without gas. After the procedure itself, you can go to the toilet and then go to donate blood.

If the ultrasound procedure is performed transvaginally, then filling the bladder is not required. Screening is assigned to a woman by a doctor. The terms of screening of the 1st trimester are strictly limited: from the 10th week to the 6th day of the 13th week. It is best to screen at week 12, at which time the chance of error is minimal. The duration of pregnancy and the date of screening are calculated by the doctor.

It is carried out on an empty stomach. It is advisable to maintain an interval of 4-6 hours after the last meal. It is recommended to go on a diet for some time before screening: exclude all fatty, creamy, chocolate, fried foods. If these simple rules are observed, the accuracy of the results increases.

In the first trimester, a woman can be tormented by toxicosis, nausea, her taste preferences change. Before donating blood, it is not recommended to eat anything, even to reduce nausea, as the blood will quickly clot and will be unsuitable for examination.In order not to endure the urge to urinate before an ultrasound, you need to go to the toilet 2 hours before the examination, and then drink a couple of glasses of water. It should be pure non-carbonated water, but not tea, coffee, juice.The screening ultrasound procedure itself is no different from any other, but the equipment is more powerful, and the doctor has a sonologist specialization.

Ultrasound can be performed either transvaginally or transabdominally.

In any case, there will be no pain. A woman enters the doctor's office, exposes her stomach or takes off all her clothes to the waist and lies down on the couch. The doctor lubricates the surface of the abdomen with gel and runs a sensor over it.

With transvaginal ultrasound, the probe has an elongated shape. The doctor puts a special disposable nozzle on him and lubricates with gel. The sensor is inserted into the vagina shallowly, so there should not be any discomfort. If spotting occurs, the doctor will stop the procedure. The presence of a small amount of discharge on the day of the ultrasound or the next day is considered normal.


During the procedure, the size of the embryo, the size of the heart and brain are assessed. Sometimes the position of the fetus does not allow to evaluate all its parameters. In this case, the expectant mother is recommended to stand up, walk around, cough, so that the embryo changes its position.

It is desirable to conduct screening no earlier than 11 completed obstetric weeks, so that the size of the embryo allows a good view of its organs.

During the ultrasound procedure, the following parameters are evaluated:

  • Coccyx-parietal size. The size of the embryo from the coccyx to the crown of the head is the most important indicator of its normal development. At the 11th week of pregnancy, this size can reach 42-58 mm, depending on the period. At the end of the 12th week of pregnancy, the CTE already reaches 60-70 mm.
  • Heart rate. The heart rate of the embryo may increase, but more often the heart rate becomes smaller with the growth of the fetus. So, on the 10th week, 160-179 beats per minute is considered the norm, and on the 12th week - 150-174 beats per minute.
  • . The thickness of the collar zone at the 13th week should be no more than 3. A thickened collar zone may indicate a risk of the child developing Down syndrome and other serious congenital diseases, which can only be reliably detected in late pregnancy.
  • biparietal size. This is the distance between the parietal bones. At the 13th week of pregnancy, it should not exceed 26 mm. A slight deviation in the norm of this indicator does not always indicate pathology, more often it is a feature of development or an incorrectly set period. The increased size of the fetal head indicates either that it is large (if the other sizes are also larger than normal), or that it may develop hydrocephalus.
  • The size of the nasal bone. The size of the nasal bone can only be assessed from the 12th week of pregnancy. Therefore, the bone is visible, but its size has no diagnostic value. At the 12th week, the size of the nasal bone is more than 3 mm.
  • Brain. Normally, the hemispheres of the brain in the embryo develop symmetrically. Its structures are evaluated.

Deciphering: the norm of a blood test

A blood test during pregnancy is an important indicator of the health of the body of the pregnant woman and the fetus.

When screening in the first trimester, it first of all shows the level of hormones necessary for the normal development of the fetus. is carried out before and specifies the gestational age, whether it coincides with obstetric. This is important, since blood counts depend on the period.

Since the examination is carried out on an empty stomach, it is recommended to take some food with you so that you do not become ill after the blood sampling.

It is advisable to exclude all foods that can be strong allergens 2-3 days before donating blood. This should be done even if the woman has never had an allergic reaction. Seafood (especially shrimp and mussels), chocolate, citrus fruits, honey are excluded from the diet of a pregnant woman.

The main blood parameters that are taken into account during screening in the first trimester are hCG and PAPP-A.

The hormone is called the pregnancy hormone or human chorionic gonadotropin. The level of this hormone helps determine pregnancy even before a delay. At the 12th week of pregnancy, the level of hCG reaches its maximum, and then gradually decreases. The boundaries of this hormone are very wide and often depend on the individual characteristics of the mother's body and the fetus itself. So, for example, at the 12th week of pregnancy, the hCG level ranges from 13 to 128 units. Both that, and other indicator will be considered as norm.

The blood level rises not only with Down syndrome, but also with a severe form of toxicosis and multiple pregnancy, which is determined in advance by ultrasound. A low level of hCG may indicate an ectopic pregnancy, which will be shown by ultrasound, as well as a high risk of abortion. In this case, the woman can be put on hold.

Useful video - First screening during pregnancy:

PAPP-A is the one that is being developed. He is responsible for its normal development and functioning. A deviation in the norm of this indicator may indicate the presence of chromosomal diseases in the fetus. At the 12th week, the level of this protein normally reaches 1-6 mU / ml. Reduced levels of PAPP-A are considered potentially dangerous due to the high risk of miscarriage.

Possible fetal pathologies

Screening of the first trimester helps to identify a large number of fetal pathologies. Not all pathologies require termination of pregnancy, some are corrected and observed.

Also, the doctor should warn that the first screening indicates possible pathologies or a high risk of their occurrence, but as a result of the following ultrasound, they may be absent:

  • Down Syndrome. Children with Down syndrome have an extra chromosome. On ultrasound during the first screening, the nasal bone is not visualized in the fetus, and the collar space is thickened. The thicker the collar space, the more likely the birth of a child with developmental anomalies. Approximately one third of all pregnancies where the child has Down syndrome end in spontaneous miscarriage or fetal death. Children with a similar syndrome have a serious developmental delay, characteristic facial features: a flat face, a flat bridge of the nose, weakly pronounced brow ridges.
  • Edwards Syndrome. If Down syndrome is known to everyone, then many women have not heard of Edwards syndrome. This is a genetic disease in which one of the chromosomes is duplicated. The reasons for the development of this disease are unknown. A child with this disease can be born to perfectly healthy parents. Children with Edwards syndrome have low birth weight, an underdeveloped jaw, cleft palate or cleft lip, and developmental delay. The prognosis is poor, children with this syndrome do not often live to adulthood.
  • Pathology of the development of the neural tube. Neural tube defects are quite common among other developmental anomalies. To prevent the development of these defects, the mother is recommended to start drinking folic acid even at the stage of preparation for pregnancy. In children with these defects, various developmental anomalies occur: from cleft lip to brain cysts.

As a result, the MoM coefficient is indicated, showing the level of deviation in the development of the fetus. Further, using a special program, taking into account all the data and the woman's history, the ratio is calculated. For example, if 1:300 is indicated, this means that one out of 300 women with the same data gives birth to a child with genetic abnormalities.

Screening of the 1st trimester, what is it and when should it be carried out? Is it mandatory and how accurately are the results interpreted? This examination is a combination of two - ultrasound and blood tests, which must take place on the same day.

Prenatal screening in the 1st trimester is considered reliable if 2 conditions are met.
1. It was performed by an experienced specialist in terms of 11 to 13.6 weeks. In this case, the CTE of the fetus should not be less than 45 mm, otherwise the measurement of TVP (collar space) cannot be considered reliable for calculating the risk of having a child with chromosomal pathologies.

2. Risks should be considered, not relying only on ultrasound data, and not looking only at biochemical screening of the 1st trimester. This work must be performed by a special program. And it will give a result on the risks for various genetic and chromosomal diseases. The risks will be registered as average (where only age is taken into account) and individual. So the screening of the 1st trimester is bad if the individual risks are higher than the base (age). In this case, the doctor may refer you for a consultation with a geneticist. And already he, perhaps, will prescribe as soon as possible to repeat ultrasound, only an expert class and (or) invasive diagnostics (cordocentesis, chorionic villus biopsy or amniocentesis). Recommendations will largely be based on ultrasound data. Sometimes at this time, the doctor of ultrasound diagnostics sees very severe malformations in the fetus that are incompatible with life. In this case, a second ultrasound is prescribed and interruption is recommended. Invasive diagnosis is usually not necessary.

If the ultrasound screening of the 1st trimester is generally normal, but the individual risk of having a sick child is high, then the doctor may recommend waiting for the second screening or conducting an invasive diagnosis, the result of which will tell you exactly whether the child is genetically healthy.

In the early stages, a chorionic villus biopsy is performed - this is a rather risky procedure, in terms of a high risk of miscarriage after it. For genetic analysis, the doctor takes cells from the placenta, this procedure is also called a placental biopsy.

After 16 weeks, amniocentesis is done. Amniotic fluid is taken for analysis. This analysis is considered very informative and safer than chorionic villus biopsy and cordocentesis. Women usually agree to the first one in order to avoid prolonged bearing of a non-viable fetus. After all, after 12-13 weeks, you need to wait for the period when doctors can induce artificial labor. And that's about 18 weeks.

But if you didn’t fall into the norms of screening for the 1st trimester by ultrasound, and you don’t want to wait for the second screening, and even more so for invasive diagnostics, there is an opportunity to do a non-invasive test. While in Russia it is not common. And very expensive. An analysis costs about 30,000 rubles. But its reliability is about the same as amniocentesis. There is no risk of spontaneous abortion.

1st trimester screening involves looking at the levels of two hormones in the blood of the expectant mother - hCG and PAPP-A. High hCG may indicate a high risk of Down syndrome in a child, and low hCG may indicate Edwards syndrome. At the same time, PAPP-A is also low. But the final interpretation of the results of screening of the 1st trimester is performed only together with ultrasound.

The result of blood tests can be affected by a situation where a woman has a clear threat of miscarriage if she takes progesterone preparations. But with the threat flow very many pregnancies. In addition, a woman carries one or several fetuses, whether she has excess or underweight, whether the conception was natural or in vitro fertilization. Therefore, it is completely wrong to try to interpret and worry about separate blood tests.

When it is better to do screening of the first trimester - the gynecologist can and should calculate directly. That is why it is important to register for pregnancy before 12 weeks. It is advisable to come to the doctor for the first time no later than 8-9 weeks, since there is a shortage of coupons for free screening in many Russian regions. You may need to wait a bit to get a coupon. You just have to wait for this extra time.

But the timing of the screening of the 1st trimester has been determined. It remains only to donate blood and do an ultrasound on the specified day. Many women believe that for greater reliability of the result, some measures need to be taken. Should there be preparation for the first screening during pregnancy and what kind? As such, no preparation is needed. Some experts recommend following a diet a few days before the examination, but this is not very necessary. There is no need for a future mother to limit herself in nutrition. And one more important question - how is the first trimester screening done on an empty stomach or not, what is the best way? In general, it is advisable to take all blood tests on an empty stomach. Including this one. But sometimes it happens that the analysis is scheduled for the second half of the day. Then, of course, you should not starve from the evening of the previous day.

An ultrasound is performed. And sometimes the doctor needs not only abdominal access, but also vaginal. Indicators that are of particular interest to the doctor are the thickness of the collar space, the visualization and size of the nasal bone, and the speed of venous blood flow. In addition, the doctor looks at all the organs and systems of the fetus, the size of the limbs, the head. Measures the cervix of a woman in order to diagnose isthmic-cervical insufficiency at an early stage, if any.

The results of the 1st trimester biochemical screening are usually ready within a few days. And all this time, the expectant mother is in suspense. Especially if you read or personally know the bad stories associated with this survey. Usually a woman visits a doctor once every 2-3 weeks, and if a high-risk screening result arrives before she is due to attend an antenatal clinic, the doctor or midwife calls her and invites her to come. If there is a good screening of the first trimester, you don’t have to worry and additionally don’t take anything and don’t visit genetics. It should be noted that young women have a much lower risk of chromosomal abnormalities.

Screening of the 2nd trimester consists in the delivery of three blood parameters. But it is usually prescribed only to those women who either did not pass the first screening, or its results were unsatisfactory.

And in conclusion, it should be said about how much the first screening is generally needed. Is it possible to do without it? Of course, yes, it all depends on the desire of the woman. On ultrasound at 12 weeks, severe malformations can be detected. Well, high or low risk is not a guarantee of the birth of a sick or healthy child.

However, classical screening is recommended to be mandatory for women over 35 years of age and those who already have children with genetic abnormalities, or cases of bearing children with chromosomal abnormalities, if there are deviations in the genetic code.

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Prenatal or 1st trimester screening - what is this procedure? How does it go and what does it show? These questions are often asked by expectant mothers on the eve of the examination.

Screening is just a diagnosis that is carried out in order to identify possible pathologies, disorders and genetic abnormalities of the intrauterine development of a child. The deadline for the appointment of the procedure is not earlier than 11 weeks. It is mandatory to pass it up to 13 weeks and 6 subsequent days during pregnancy:

  • the age of the future mother is more than 35 years;
  • cases of fetal fading;
  • miscarriages;
  • infectious and inflammatory past diseases;
  • possible genetic risk of complications, existing pathologies of the previous fetus;
  • family ties between parents;
  • the presence in the family of cases of alcoholism, drug addiction, smoking;
  • work in hazardous production;
  • taking illegal drugs.

The very first screening is carried out in accordance with the decree of the Ministry of Health. At what week it is necessary to do it is decided by the gynecologist. Usually no later than 13 expected weeks. The scheduled screening of the 1st trimester includes an ultrasound scan, a blood test, and a thorough biochemical analysis of its composition.

Diagnosis at the first ultrasound

Usually performed when fertilization is suspected. Already from the second week of the alleged menstruation delay, an ultrasound examination shows the presence of pregnancy, the approximate timing of the fetus, its development and possible diseases or disorders. It passes abdominally, that is, the abdominal wall is used for research, without insertion into the vagina. Required preparation:

  • diet. Approximately 3 days before the scheduled study. Do not eat legumes, cabbage, carbonated drinks, bakery products, fruits before ultrasound;
  • filled bladder. 3 hours before the ultrasound, you can not urinate;
  • carried out strictly on an empty stomach. You can not eat food 4 hours before the diagnosis.

Less commonly, a transvaginal or pelvic ultrasound may be performed. More informative. Diagnosis takes place with the introduction of an ultrasound probe into the vagina. Preparation and special diet is not required. Screening indicators during pregnancy in the first weeks:

  • position of the uterus. Meaning "anteflexio";
  • contours. Should be defined as equal;
  • uterus dimensions: 70mm x 60mm x 40mm. Correspond to length, width, diameter;
  • walls. Echogenicity is homogeneous;
  • fertile egg. Diameter up to 5 mm or more, depending on the period;
  • decidualization of the endometrium. Indicates the onset of pregnancy;
  • the uterine cavity is homogeneous;
  • ovary sizes. Width, length and thickness correspond to the values: 25mm x 30mm x 15mm.

Usually, such an examination is included in a regular medical examination. Not always a gynecologist can determine pregnancy on their own. If the pregnancy test shows a positive result, further diagnosis is carried out in the early stages. It is impossible to do an ultrasound earlier than 1.5-2 weeks after a delay in menstruation.

Ultrasound at 12 weeks

Appointed by a gynecologist. It is carried out within the clinic by specialists from 11 to 13 weeks. To determine pathologies and disorders of fetal development and pregnancy. Preparation required:

  • diet. For 3 days, the complete exclusion of sweets, chocolate, seafood, fatty foods, legumes and cabbage;
  • do not urinate 2-3 hours before the study. When conducting abdominal, external ultrasound.

In a timely manner, ultrasound shows the possible genetic risk of having an affected child. Further study of the problem is required. The first weeks of childbearing are very important. The norm of the following values ​​should be indicated in the results:

  • embryo size. The measurement is taken from the head to the coccyx. KTP indicator;
  • temple to temple distance. BPR data;
  • thickness, density of the collar space, TVP;
  • calculation of heart contractions and their frequency, heart rate.

To find out the sex of the child through ultrasound at week 12 is the dream of all future parents. But it cannot be determined exactly. There are too many mistakes on the part of doctors. It is better in this case to conduct an ultrasound at the 16th week of fetal development.

Norm and interpretation of results

Many patients specify which week is best for ultrasound screening. If there is data from a previous ultrasound, the exact dates are assigned, which suggest 12 weeks of pregnancy. In other cases, the timing shows a gynecological examination. The norm and interpretation of the results of the first ultrasound should have indicators:

  • 10 weeks. KTR 33 - 41 mm. TVP up to 2.2 mm. The nasal bone is visible. The heart rate is 161-179 beats. BPR 14 mm;
  • 11 weeks. KTR up to 50 mm. TVP - up to 2.4 mm. The nasal bone is visualized. Heart rate - 153 - 177. BDP 17 mm;
  • 12 weeks. KTR up to 59 mm. TVP up to 2.5 mm. The nasal bone is more than 3 mm. The heart rate is 150-174. BPR 20 mm;
  • 13 weeks. KTP not more than 73 mm. TVP up to 2.7 mm. Nasal bone more than 3 mm. Heartbeat - 147-171. BPR 26 mm.

In addition to these data, the circumference of the baby's head, the structure of the brain, the distance from the bones: frontal and occipital are determined. The forearms, pelvis and thigh bones are visible. Dimensions of the heart, ventricles. The doctor takes into account the amniotic fluid, the thickness of the placenta. Poor ultrasound results are also possible, which indicate the genetic risk of developing a sick fetus and the corresponding syndromes:

  • Down. TVP or collar skin fold on the baby's neck has a width of up to 2.8. It is filled with liquid. With Down's syndrome, the liquid is dark in color. The nasal bone is shortened, the distance between the eyes is increased, tachycardia and heart pathologies are observed;
  • Edwards. There is bradycardia or a decrease in heart rate in the fetus, there is no nasal bone, only one artery is observed in the umbilical cord, a hernia of the abdominal cavity;
  • Patau. Bladder enlargement, tachycardia, impaired brain formation;
  • Turner. The fetus has a rapid unnatural heartbeat, a developmental delay corresponding to 8 weeks of pregnancy;
  • Smith-Lemli-Opitz. Hereditary genetic disease. The reason is a violation of cholesterol metabolism. It is characterized by mutations, craniofacial anomalies, neurological abnormalities;
  • de Lange. A disease in which the genetic risk factor is 25%. The condition is possible mutations in the parents. In the fetus, a false-positive result is 5%;
  • triploidy. Lack of division into the corresponding parts of the brain, holoprosencephaly. Decreased heart rate, bradycardia. Omphalocele, or misalignment of the abdominal organs. An increase in the pelvis of the kidneys and more than two cysts in the region of the skull.

For further examination, blood is taken from the pregnant woman, as well as taking samples from the fetus. If at least one of the above violations is found, the pregnancy is terminated. That is why screening is so important. Any deviation from the norm raises the suspicion of a specialist.

Biochemical screening

This examination must be done immediately after the ultrasound diagnosis. What is it: biochemical screening? When the gestational age is revealed, all indicators of fetal development are indicated, it is necessary to conduct a biochemical blood test or genetic screening. How is the preparation going:

  • exclusion from the diet of foods that cause allergies. Chocolate, smoked products, seafood;
  • a ban on fatty foods;
  • analysis strictly on an empty stomach. It is forbidden to drink even water.

It is advisable to study the hormonal composition of the blood on the same day as the ultrasound examination. Then the doctor will be able to objectively evaluate the results and the data obtained. The norms of the biochemical composition of blood are considered according to three indicators. These values ​​are: human chorionic gonadotropin β-hCG, PAPP-A protein and MoM.

Biochemical screening results: β-hCG data

It appears as a second strip when passing a regular pregnancy test at home. HCG indicators are ambiguous. If it is elevated in the blood, it is possible that future parents should expect twins. Deciphering the results of β-hCG in ng / ml:

  • 10 weeks from 25.8 to 181.6;
  • 11 weeks from 17.4 to 130.4;
  • 12 weeks from 13.4 to 128.5;
  • 13 weeks from 14.2 to 114.7.

If beta-hCG is elevated at any stage, the fetus may develop Down syndrome, and the mother has diabetes or toxicosis. A decrease in the rate of β-hCG warns of a possible pathology, such as Edwards syndrome, the risk of miscarriage, placental insufficiency, or ectopic pregnancy. Up to 12 weeks, this hormone increases, but within the normal range. After - it goes down.

PAPP-A norm at 12 weeks

A protein, protein-A, which is produced during pregnancy by the placenta. It indicates the normal course of fetal development. If PAPP-A is elevated, a woman may have a pregnancy failure or miscarriage. A decrease in protein indicates genetic diseases. Indicators of the PAPP-A norm in the blood:

  • 10-11 weeks. PAPP-A from 0.45 mU/ml to 3.73 mU/ml;
  • 11-12 weeks. PAPP-A from 0.78 mU/ml to 4.77 mU/ml;
  • 12-13 weeks. PAPP-A from 1.03 mU/ml to 6.02 mU/ml
  • 13-14 weeks. PAPP-A from 1.47 mU/ml to 8.55 mU/ml.

Low rates are a genetic risk of pathologies. Diseases like Down syndrome, Edwards, de Lange. This analysis is only valid up to 14 weeks. In the second trimester, it becomes uninformative.

After all the data received, the doctor calculates the coefficient of deviation from the norm, MoM. It usually ranges from 0.5 to 2.5. If it is exceeded to a value of 3.5, then there are several embryos. The final form of the result can be "positive" for pathology and "negative". The follow-up examination will take place already in the 2nd trimester.

The approximate cost of this procedure depends on the location of the procedure. Prenatal type of diagnosis will cost 1600 rubles. The difference between ultrasound and biochemical blood sampling for research should not be more than 5 days. You must have all the data from previous examinations with you.

1st trimester screening: what diagnostics should show

The first perinatal screening is a comprehensive diagnosis of the future mother, which is carried out even before the birth of the baby from 10 to 13–14 weeks of intrauterine development. A classic study of this kind combines only 2 main types of medical manipulations - biochemical analysis of maternal serum and ultrasound of the fetus.

Upon completion of the tests, the obtained data will be monitored, based on a comparison of the result with the indications of the screening norm for ultrasound of the 1st trimester. The main task of an individual examination is the early detection of genetic pathologies in the fetus.

Indications for carrying out

Despite the fact that the primary diagnosis is carried out for many pregnant women, there are special categories of patients who are primarily required to undergo an ultrasound scan and take a blood test in order to eliminate the danger to the life of the unborn child and their own health. This group of people includes expectant mothers who:

  • have previously given birth to children with any developmental disabilities;
  • already have a child with fixed genetic pathologies;
  • crossed the threshold of 35–40 years;
  • were exposed to infectious diseases during the period of gestation;
  • have ever suffered from excessive use of alcohol or drugs;
  • have a history on hand with notes about the threat of spontaneous miscarriage;
  • are with the potential father of the baby in a closely related union;
  • for any reason, they took medications that are prohibited for use during the gestation period;
  • know about the presence of hereditary anomalies in the pedigree of the family;
  • have experienced a stillbirth in the past;
  • received a diagnosis indicating the cessation of the development of the child;
  • show an independent desire to analyze the risk of having an infant with special forms of the disease.

Smoking during pregnancy is the basis for mandatory screening in the first trimester

How are the results of a fetal screening ultrasound deciphered?

Ultrasound diagnostics are prescribed, as a rule, from 10–11 weeks to 13–14 weeks, since this period of the obstetric period provides the first real opportunity to study the basic structures of the emerging baby. 11-12 weeks is a special period characterized by the transformation of the embryo into a fetus.

There is a list of the most important indicators of fetal development, which formed the basis for decoding the conclusion of the ultrasound. These include: KTP, PAPP-A, heart rate, BDP, TVP, hCG, NK, etc. In order to establish an accurate prediction of the course of pregnancy, a specialist needs to compare the personal data of his patient obtained during the first screening with the approved standards that are prescribed in the respective tables.

Coccyx-parietal size

KTP is one of the most important indicators of 1 screening during pregnancy. This parameter indicates the length of the embryo / fetus, which is measured from the crown (top of the head) to the coccygeal bone. In the case of deviations of the CTE from its normal range, it can be assumed that the intrauterine development of the unborn child is endangered.

According to medical observations, the digital designation of the coccygeal-parietal size increases as the gestational age increases. Sometimes a decrease in the index in question indicates an incorrectly established age of the fetus. In this case, we can talk about one of the varieties of the norm. In order to make sure of the diagnosis, the patient should sign up for the 2nd ultrasound appointment.


KTP is one of the main indicators of the condition of the fetus

Heart rate

Regular medical monitoring is necessary for the state of heart rate, since if there are pathological processes in the baby's body, they will be detected in time. If the anomaly is detected at an extremely early stage of its development, the likelihood of a favorable outcome will increase.

Up to 3-4 weeks, the baby's SS rhythm matches the mother's heart rate. The average value is in the range from 76 to 84 beats per minute during the normal functioning of the woman's body.

Further, when the heart structure of the fetus enters a new stage of natural improvement, the number of its contractions will begin to increase evenly. Every 24 hours, the value will exceed the previous "record" by approximately 2.5-3 units. So, by 8–9 weeks, the heart rate of a child developing according to the approved norm will reach 172–176 beats / min.

If before the 83–85th day of gestation, using ultrasound diagnostics, such dangerous phenomena as fetal deformity or the complete absence of a heartbeat were not recorded, then a missed pregnancy can be excluded from the list of possible pathologies. The subsequent phases of body formation are less difficult than a 12-week "Spartan marathon".

Provided that improved and high-quality models of medical devices are used for screening, potential parents will be able to get a more informative characterization of the child's current condition. It is not worth resorting to 3D / 4D ultrasound without special need. Such modern devices, although they can register the intrauterine activity and appearance of the baby, but their radiation dose during the abuse of ultrasound can adversely affect the health of the child.

nasal bone length

Changes in the structure of the oblong nasal bone also indicate the presence of abnormalities. Examining the state of fetuses diagnosed with congenital ailments, scientists came to the conclusion that a genetic failure is often expressed in the underdevelopment of the bone structures of the nose. The first screening during pregnancy to determine the length of the nasal bone (NC) is performed no earlier than 12-13 weeks. If the doctor scheduled an ultrasound session at 10-11 weeks of pregnancy, this means that he only needs to make sure that the nasal bone is present.

In medical practice, there are often significant deviations from the norm of ultrasound, which in fact turned out to be a manifestation of the individuality of the unborn child. In this case, the performance of other tests will comply with the standard.

Collar space thickness

The main task of the TVP study is to measure the thickness of the fold located on the back of the neck. When the main organ systems are formed in the fetus, the region of the collar space begins to fill with a special fluid, the amount of which is subjected to careful analysis.

If the indicator at the first screening exceeded a thickness of 3 millimeters, then it is possible to suspect damage to chromosome segments with a high degree of probability.

Study of the structure of the yolk sac

In simple terms, the yolk sac is a temporary organ that helps maintain the life of the embryo at the initial stage of its formation. From the moment of conception, this important neoplasm is several times larger than the size of the future baby.

It should be noted that the detection of deformation of the yolk vesicle or an overestimated / decreased indicator during screening, in most cases, indicates the development of a dangerous disease, for example, Down syndrome. Sometimes, under such circumstances, a missed pregnancy is diagnosed - the premature death of the embryo.

The 1st screening should not be neglected, since with its help the sonologist will be able to examine the unique structure more closely, making appropriate conclusions about its condition. If the yolk sac is at risk of destruction, immediate medical attention is needed. This is due to the fact that the bubble formed only for 3-3.5 months controls many processes in the child's body.

Its most notable features include:

  • isolation of extremely important protein structures involved in the construction of protective membranes for embryonic cells;
  • the formation of a capillary network and red blood cells, which will become the "foundation for laying" the circulatory system of the fetus;
  • temporary replacement of the liver;
  • determination of the sex of the child by delivering to him the gametes developed in the cavity of the yolk sac.

Also, this organ is responsible for protecting the small organism from the mother's antibodies. No matter how ambiguous it may sound, but the cells of the woman's immune system, like soldiers on guard of human health, attack the fetus, seeing it as a potential threat - a foreign element. In order to provide the embryo with a safe environment, the yolk sac actively secretes hormones that begin to participate in the process of lowering blood pressure, “pacifying” immune resistance and preparing the mammary glands for breastfeeding.


After 12-14 weeks, the bubble stops its activity, gradually transforming into a cystic inclusion, localized near the umbilical cord

Location of the placenta

The localization of the placenta affects the course of the upcoming pregnancy, therefore, with a comprehensive examination, it is given a lot of time. According to the medical standard, this organ should not be located in the lower region of the uterus, since its abnormal structure provokes the overlap of the birth canal. Such a frequent gynecological deviation is called presentation.

The detection of an ailment at the first screening during early pregnancy is far from always a cause for concern. At an early stage, there is still a chance to change the extremely precarious position - in the subsequent time of gestation, the uterus may rise, while taking its proper place. If a favorable outcome is not observed, doctors begin to develop a detailed action plan, which implies individual indicators for a particular patient.

Biparental fetal head size

BDP is an extremely important index, also registered in the results of the first screening. Without going into the details of medical terminology, we can say that this indicator involves measuring the head along the minor axis - the distance from one temporal bone to another. The biparental size of the fetus is of particular value, primarily because of the direct relationship to the brain located in the cranium.

Since this organ is the main element of the central nervous system, as well as the central processor of the body system, its condition is monitored with special attention by an ultrasound specialist.

If there are no suspicious signs in the final screening data, then the brain develops in the normal mode. A lower index indicates a lack of any parts of the brain or a delay in its development.

Blood chemistry

After the results of ultrasound diagnostics are obtained, on the basis of which the actual gestational age is determined, the pregnant woman will have to go through the final stage of the perinatal examination - blood biochemistry. Screening involves conducting 2 tests, each of which helps to identify elements of protein origin - PAPP-A and hCG.


2-3 days before the blood biochemistry of the expectant mother, it is recommended to reduce the amount of consumption of fast food, spices, nuts, fatty foods, chocolate and confectionery

PAPP-A is a special hormone (plasma protein A) responsible for the gradual and safe development of the child in the womb. Usually, indicators of its content are found out only from 12–13 weeks, however, as an exception, the blood sampling procedure is carried out a little earlier.

Chorionic gonadotropin is also a hormone that, unlike protein A, begins to be produced immediately after conception. It is noteworthy that its amount actively reaches its maximum value at 11-12 weeks, then the level of hCG content gradually drops, fixing at a stable rate.

As soon as the patient passes the perinatal screening in full, doctors will begin to compare the identified indices with the norm, drawing up a full-fledged final conclusion.

What pathologies can be detected at the 1st screening?

With the help of a comprehensive study in the first trimester, you can find a fairly impressive list of pathologies that cause complications of various severity, starting with the deformation of an organ and ending with the death of a baby. The most commonly diagnosed ailments include:

  • hydrocephalus;
  • glioma;
  • Down syndrome;
  • cerebral hernia;
  • astrocytoma;
  • Shershevsky-Turner syndrome;
  • omphalocele;
  • aneurysm;
  • Patau syndrome;
  • bradycardia;
  • meningocele;
  • intrauterine infection;
  • Edwards syndrome;
  • hypoxia;
  • tachycardia;
  • Smith-Opitz syndrome;
  • developmental delay;
  • anemia;
  • hemimelia (underdevelopment of the limbs);
  • Cornelia de Lange syndrome;
  • heart disease.

The above congenital diseases have the right to diagnose only a doctor, since the decoding of ultrasound performed by the patient on his own may be done incorrectly. The formation of a diagnosis based on the indicators of the first screening implies a comprehensive qualitative analysis of all the data obtained, taking into account each aspect and the "pitfall". That is why expectant mothers are advised to trust their health and the life of the baby only to a professional in their field. The constructive unity of the patient with the attending physician increases the likelihood of having a healthy child.

During pregnancy, a woman's doctor prescribes many different tests and procedures, including prenatal screening (PS).

In general, prenatal screening is a set of studies aimed at identifying fetal diseases. Thanks to screening, the baby can be tested for a number of serious diseases while still in the womb, which will not only prepare the mother for his future condition, but also help prevent a number of problems.

What is prenatal screening

Produced studies are easy to conduct and safe for mom and baby, so they are assigned to all pregnant women.

The prenatal screening program includes:

  • Ultrasound (ultrasound),
  • biochemical screening (blood test for markers).

Prenatal screening does not provide a specific diagnosis.

It only makes it possible to determine the likelihood of a particular pathology and identify women with specific risks.

To make a diagnosis, additional studies are required, such as consultation with specialists and invasive diagnostics.

Disease Risk Check

Screening can detect markers of diseases such as:

  • Down Syndrome,
  • Edwards Syndrome,
  • turner syndrome,
  • Smith Lemli Opitz Syndrome,
  • patau syndrome,
  • Cornelia de Lange syndrome
  • neural tube defect
  • triploidy.

Basic risks

Every pregnant woman is at risk of chromosomal abnormalities. In this regard, biochemical screening can be carried out at will and is recommended for any pregnant woman, but is mandatory if there are certain indications. Among them:

  • age over 35 years old,
  • multiple pregnancy,
  • spontaneous miscarriages,
  • the birth of a child with a congenital pathology,
  • hereditary diseases,
  • the threat of miscarriage in the early stages,
  • viral infections in the early stages,
  • taking medication early
  • mother's alcohol or drug addiction,
  • increased levels of harmfulness at work and at home,
  • conception from a close relative.

Before screening begins, the baseline risk is determined, which depends on the duration of pregnancy and the age of the expectant mother. It is also called original.

Research results (individual risk) are presented as a ratio of two numbers. For example, 1:1415. This ratio means that one out of 1415 pregnant women with similar baseline indicators has a child with the abnormality for which she was tested.

Factors affecting the result

As mentioned earlier, there are some factors that can affect screening results and should be taken into account during the procedure. These include:

  • race (in the Negroid, AFP and hCG are higher than in the European),
  • body weight (with too much weight of a woman, the indicators are increased and vice versa),
  • IVF application,
  • multiple pregnancy (indicators will be overestimated, it is not advisable to carry out, since one of the fetuses may have diseases, and the second will be healthy),
  • the possibility of miscarriage (recommended to postpone),
  • diabetes,
  • colds and other similar diseases,
  • bad habits
  • human factor (for example, the doctor indicated the wrong term in the direction).

Effectiveness of prenatal screening

The effectiveness of screening directly depends on the health of the pregnant woman and the factors that have just been discussed.

Any minor illness and even ordinary stress can lead to a change in the composition of the blood, so doctors recommend taking tests only in good health and a relaxed state.

Equally important is the quality of the tests carried out, as well as their methodical nature, that is, strict adherence to the above scheme in compliance with the terms of pregnancy.

When undergoing screening, it should be remembered that these methods can only detect some genetic diseases.

Having successfully passed the test with normal results, a woman cannot be 100% sure that her baby will not have other congenital diseases.

At the same time, positive results also do not guarantee that the child will be born with pathologies. A woman must weigh all the pros and cons herself, making a decision about the future fate of her fetus.

False negative result

The situation is reversed with false-negative results, when the mother of the unborn child received good results after passing the tests, but the baby was born with pathologies. Such cases once again prove the exemplary nature of research.

False positive result

The situation when a child had a high probability of chromosomal defects, but was born without them, means that the result was false positive. This scenario may cause additional examinations of the child after birth. For a mother, such a turn becomes a real happiness.

Prenatal screening 1st trimester

For a period of 10-13 weeks, the doctor should prescribe the first screening for a pregnant woman. It includes 2 safe procedures: ultrasound and blood donation for a special test.

First screening ultrasound

The first ultrasound allows you to identify gross defects that have arisen during the development of the fetus. Among them, anencephaly, cervical hygroma, omphalocele and other specific anomalies may occur. During the examination, the doctor checks the viability of the embryos, their number, and also sets a more accurate gestational age.

Collar space thickness (TVP) becomes the main indicator of genetic diseases. To determine it, the width of the layer of subcutaneous fluid on the back of the child's neck is measured. Normally, this indicator does not exceed 2.7 mm. If the value of TVP is higher, then the risks increase significantly.

In addition to TVP, the doctor examines the nasal bone, which is present and clearly visualized in a fetus without chromosomal abnormalities, and examines for congenital malformations. Those data that are outside the norm are called disease markers. The more of them were found, the higher the likelihood of genetic abnormalities.

However, the appearance of only one of them is not the reason for the diagnosis.

"Double Test"

Biochemical screening in the first trimester is limited by rigid time frames. If you donate blood a little earlier or later, then its accuracy will drop sharply, so you need to know exactly the gestational age.

Counting the menstrual cycle does not always give the correct result, especially if it was irregular or if the pregnancy occurred immediately after childbirth. Given this factor, a double test is prescribed by a doctor after an ultrasound scan, where exactly the number of weeks of pregnancy will be determined.

The "double test" is an analysis to determine the level of specific placental proteins in the blood. Specifically, the content of two proteins is detected (hence the name of the test):

  • β - hCG - free beta subunit of human chorionic gonadotropin,
  • PAPP-A - protein of pregnancy (Pregnancy-associated Plasma Protein-A).

Blood is taken from a pregnant woman from a vein, in the morning on an empty stomach. The normal value of hCG depends on the equipment on which the blood test was performed. They are always indicated in the results of the analysis so that they can be adequately evaluated. The average value of the hCG level among women with the same period is indicated by the median. And the ratio of the hCG level to the median is designated MoM (multiple of median). Permissible fluctuations of this indicator are 0.5-2.

For more information on what is MoM, read

If the level of these proteins deviates from the norm, there is a high risk of chromosomal and some non-chromosomal defects in the fetus. If the deviations are serious, then the pregnant woman is sent to genetics. In other cases (with small deviations), doctors recommend not to panic, but to wait for the second screening, which will clarify the situation.

Read more about the norm and deviations from the norm of the level of hCG, read

An analysis of the protein level of pregnant women is also carried out with an indication of the normal values ​​​​and the actual value of the expectant mother.

An increase in the concentration of PAPP-A is not as dangerous as a decrease. The level of this protein can be elevated due to multiple pregnancies, a low placenta, or even severe toxicosis. A decrease indicates congenital pathologies in the fetus or diseases in the mother. Deviations from the norm require a doctor's consultation, as each case is individual.

Read more about normal and abnormal levels of PAPP-A, read

Prenatal screening II trimester

Unlike the first trimester, screening for the second period of pregnancy begins with a blood test, after which an ultrasound is performed.

"Triple Test"

At a period of 16-18 weeks, blood is taken from a pregnant woman again from a vein and it is analyzed, but in this case the indicators will be different than during the first screening. The "triple test" makes it more likely to identify malformations of the neural tube of the fetus. Less accurate results are obtained by a test for detecting Down syndrome and Edwards syndrome (70%).

The second biochemical screening determines the concentration of the following blood components of a pregnant woman:

  • AFP - alpha-fetoprotein(fetal protein that is excreted by the kidneys and enters the mother's blood),
  • E3 - free estriol (synthesized in the placenta).

If there are any abnormalities in the development of the fetus or in its chromosomal correspondence, the levels of these proteins will differ from the norm.

In some cases, the “triple test” can be supplemented by the detection of another indicator of inhibin A (the hormone that the placenta produces), then it will be called the “quadruple test”. Determination of the concentration of inhibin may be required when it is necessary to clarify the results of the first screening, if they revealed large deviations from the norm. However, this test is not available in all clinics.

Read more about the norm and deviations from the norm of the level of AFP, read

Read more about the norm and deviations from the norm of the level of free estriol - E3, chiatite

Read more about the normal and abnormal levels of inhibin A, read

As in the case of the first screening, the obtained levels are compared with normal values, which allows to identify the deviation. The risk calculation is carried out in a specially designed computer program, the results of which are analyzed by the doctor.

The results obtained are correlated with the indicators of the first screening, and a conclusion is made only from the complex of all indicators.

Second screening ultrasound

The second mandatory ultrasound is prescribed by the doctor at 20-24 weeks. This screening allows to detect with sufficient accuracy the anatomical abnormalities of the fetus, such as malformations of the spinal cord and brain, heart, gastrointestinal a path, defects of development of extremities, facial crevices and other deviations.

If these abnormalities are detected, doctors are unable to carry out surgical treatment after childbirth, therefore they are an indication for interrupting gestation or put the mother in front of the fact that her child will be different from other children.

In addition, markers of chromosomal pathologies are evaluated at this stage, among which there may be growth retardation, shortening of tubular bones, pyelectasis, cysts in the brain, and much more.

Prenatal screening III trimester

The period closest to childbirth is accompanied by the passage of the third mandatory screening. At a period of 30-32 weeks, a woman needs to undergo another ultrasound.

With an ultrasound examination, the doctor will be able to assess those anatomical features that could not be seen before. These include narrowing of the urinary tract, some heart defects, hydrocephalus. If they are detected, they are subject to surgical correction after childbirth.

In addition to ultrasound with an examination of the structural features of the child, a pregnant woman is also prescribed dopplerometry, during which the doctor examines the blood flow in the baby's vessels, the woman's uterus and the umbilical cord that connects them. When violations with blood flow are detected, a treatment course is prescribed, which the doctor usually recommends taking in the maternity hospital in the wards for being before childbirth, that is, “lie down on preservation”.

How to calculate risks

In our country, the calculation of risks is mainly carried out using one of the following computer systems:

  • DELFIA-Life Cycle

The system allows you to calculate the probability of such pathologies as trisomy on chromosome 21 (Down syndrome), on chromosome 18 (Edwards syndrome), on chromosome 13 (Patau syndrome), on the X chromosome (Syndrome Shereshevsky-Turner), triploidy, defects of the central nervous system. The program takes into account the individual data of the pregnant woman and the factors influencing the detection of deviations. Individual indicators include the results of ultrasound in the first trimester.

  • PRISCA - Prenatal Risk Assessment

The program identifies the risks of trimosomy on chromosome 21 (Down syndrome), on chromosome 18 (Edwards syndrome) and neural tube defects. The patient's baseline and factors that may affect the final result are also taken into account.

  • "Isis"

Complex "Isida" also performs the calculation of similar PRISCA risks. This takes into account almost all factors that can give a false positive result: ethnic group, the presence of chromosome disorders in a child born earlier, and others. The advantage of the product is compatibility with automatic ELISA analyzer Alisei, from where he takes part of the data.

The difference between one system and another lies in the range of risks assessed. The effectiveness of each of the methods is almost the same. In addition to these programs, there are other less common developments.

If the results are positive

If as a result of the analyzes a risk level of more than 1:380 was obtained, then it is considered high and may require a more detailed examination.

The main thing to avoid in such a situation is panic.

Only a calm attitude will help to avoid breakdowns and give real results in further research.

Further research may include the following items:

  • genetic counseling,
  • repeated ultrasound (recommended by another specialist and with more modern equipment),
  • invasive examination (analysis of amniotic fluid, chorionic villus sampling, cordocentesis).

Repeating the "double" or "triple test" is not recommended.

Re-study

Repeated ultrasound can be prescribed in the case when the biochemical screening indicators were normal, and some external deviations were revealed on the ultrasound. The reason for this phenomenon may be the use of outdated equipment and the human factor. A re-examination will help confirm or refute the presence of such deviations.

genetics consultation

A geneticist is not a gynecologist. He is well versed in chromosomal disorders and can, by a simple conversation with a pregnant woman, find out if she is prone to genetic diseases. To do this, the doctor interrogates the patient for the presence of any serious diseases among relatives, carefully examines the tests and markers found.

Not all markers are indicators of genetic abnormalities.

There are basic and indirect indicators by which the risk is determined.

For example, if salt deposits are found in a child’s heart, then this is not a sign of pathology. In the future, they will simply turn into chords or disappear. But this marker is a confirmation of the high risk of Down's syndrome if it is found along with the pathology of the nasal bone and abnormal thickness of the collar space.

In any case, a consultation with a geneticist will allow you to get a qualified answer to the situation with the analyzes.

Invasive research

If the risk of a genetic disease turned out to be high, then it is possible to resort to less sparing studies. Invasive methods include 3 types of research:

chorion biopsy,

Amniocentesis,

Cordocentesis.

  • The safest is amniocentesis(analysis of amniotic fluid).

It can be carried out at 16-20 weeks of pregnancy. During the procedure, the doctor makes a puncture of the amniotic membrane and takes a small amount of amniotic fluid for laboratory testing. Actions are carried out under ultrasound control, bypassing the placenta. A free pocket is used to insert the needle. If there is no free space, then the thinnest section of the placenta is used. After the procedure, complications are possible in the form of a leak or premature withdrawal of water, detachment of the membranes and the development of alloimmune cytopenia in the fetus.

  • Parallel to amniocentesis for a period not earlier than 18 weeks can be performed cordocentesis.

Cordocentesis is the collection and examination of blood from the umbilical cord of the fetus. The analysis requires at least 5 ml of blood. In addition to genetic diseases, it allows you to determine the severity of the Rh conflict, if any, and, if necessary, perform a blood transfusion.

  • Chorionic biopsy consists in the analysis of chorionic villi, which are obtained by sampling chorionic tissue through the wall of the uterus.

Chorionic biopsy is performed for a period of 10-12 weeks. At least 5 mg of tissue will be required for analysis for genetic diseases. If at the first attempt the doctor failed to get enough of it, then a second sampling can be made. The third attempt can adversely affect the course of pregnancy, significantly increasing the risk of miscarriage.

An invasive study is a full-fledged operation, therefore it is prescribed only in cases of high risks of congenital pathologies, since it can cause miscarriage, infection of the fetus, the development of Rhesus conflict and other complications.

Conclusion

The passage of prenatal screening procedures is recommended for all pregnant women without exception, but doctors do not have the right to impose their opinion, therefore, the woman herself makes the decision to take tests and ultrasound examination. For women who fall into a special risk group for any reason, screening is mandatory.

Based on the screening results, doctors cannot make a diagnosis. They can only identify certain risks in a pregnant woman.

And a positive result of the presence of markers is not always accurate, and in those women in whom they were found, a healthy baby may well be born. Conversely, Down syndrome and other chromosomal abnormalities may not show up during screening. But although these studies are exemplary, they allow a woman to mentally prepare for possible health problems in her child.