Screening during pregnancy: what is it?

Pregnancy is a very exciting period for any woman. It is at this time that she should take a lot of tests and undergo various examinations, most of which the expectant mother hears for the first time. One such study is screening. Not everyone knows what this procedure is, how it is done and why, therefore, naturally, it inspires fear. Let's try to answer all these questions in detail.

What is screening and to whom is it assigned?

Screening is a group of diagnostic methods that,due to its availability, informativeness, safety, they are used on a large scale with various categories of people to detect certain signs. During pregnancy, prenatal screening is performed, which stands for prenatal screening.

Pregnancy screening is a diagnostic method used by a woman who is carrying a child and can detect severe developmental abnormalities in the fetus, as well as determining whether or not there are indirect manifestations of developmental anomalies and genetic defects. As a rule, this study is paid by appointment.

Screening is carried out in the first trimester (the allowable period of passage is 11-13 weeks), in the second and third trimester - depending on the evidence.

Who shows the procedure? In 2000, the Ministry of Health of the Russian Federation issued an order according to which screening was recommended for all pregnant women. The future mother, of course, can give up the rejection of the procedure, but this step will become rather rash and will only speak about the lack of knowledge or disregard for their own health and future baby.

The procedure is necessarily carried out by women who are in the so-called risk group, namely:

• age of 35 years and above;
• the threat of miscarriage in the first trimester;
• a history of one or more miscarriages or miscarriages in the past;
• contact with harmful substances due to the nature of the work;
• infectious diseases in the first trimester;
• chromosomal abnormalities or defects in the formation of the fetus found in the past pregnancy;
• reception in the first weeks of pregnancy of drugs that can not be used in carrying a child;
• abuse of one or both parents of alcohol, narcotic drugs;
• the presence of hereditary diseases in relatives of one of the parents;
• The mother and father of the baby are closely related.

Read more about screening at different stages of pregnancy.

Screening research is carried out in the first, second and third trimester of pregnancy. The first is performed at 11-13 weeks, if you carry out the procedure earlier or later, the results will be incorrect.

The procedure is carried out in several stages.The first is an ultrasound, during which determine such a value as the thickness of the collar space. Thanks to the data obtained, it is possible to calculate the risk of the presence of Down syndrome.

Additionally, examine the state of the chorion. This is carried out for pregnant women over 35 years old, as well as those who have had a spontaneous abortion in the past, or whose relatives had genetic diseases. This research is not done in a free clinic, so in order to conduct it, you need to contact a paid medical center.

It should be borne in mind that even with insignificant differences of values ​​from the norm, one cannot absolutely say that a child will be born with disabilities. To confirm or refute the information obtained in the course of screening, a large number of analyzes are also performed.

The next step of the study (second screening) is to determine the detailed anatomical structure of the fetus. In the same way, the general formation, the volume of amniotic fluid and its probable deviations from the normal level are checked. Screening for the second trimester is done in a period of 16 to 20 weeks.During this period, an ultrasound examination may determine the sex of the child, measure the length of the limbs. In addition to ultrasound, a blood test is required.

The last screening study (screening of the third trimester) is conducted from 32 to 34 weeks. During the procedure, the overall formation of the child is assessed, CTG, Doppler, and ultrasound are done.

Deviations that can be detected by ultrasound

The results of the ultrasound at the first screening can be judged on such deviations as:

1. Down syndrome. The most common genetic pathology. Detected in one of seven hundred cases. Conducting a screening study during pregnancy has significantly reduced the birth of children with similar diseases.
2. Omphalocele is a heterogeneous disease in which there is a violation of the process of intrauterine reduction of the physiological umbilical hernia.
3. Patau syndrome is a chromosomal pathology characterized by the presence of an extra chromosome 13 in the cells. The average prevalence is one case per ten thousand. Most of the children who were born with this syndrome, die in the first months due to the fact that the internal organs are seriously affected.On ultrasound, such a deviation can be detected by an increase in the heartbeat of the child, impaired brain formation, and delayed formation of tubular bones.
4. Edwards syndrome is a genetic disease characterized by duplication (trisomy) of chromosome 18 and manifested by a number of characteristic developmental abnormalities in the fetus during pregnancy, in most cases leading to the death of the child or to the fact that he becomes disabled. That is, instead of 46 chromosomes, 47 are formed in the fetus, because of such an extra chromosome, the pathology is differently called trisomy 18. The disease is more often observed in children whose mom's age is over 35 years old. Ultrasound can fix the heartbeat of the fetus, deviating from the norm in a smaller direction. In addition, there may be such deviations as the absence of nasal bones, the presence of only one umbilical artery, and not as expected - two.
5. Cornelia De Lange syndrome is a rare hereditary disease that, according to medical data, occurs with a frequency of 1 in 30,000 children. The fetus manifests many anomalies of development, and subsequently - mental retardation.
6. Smith-Lemli-Opitz syndrome is an autosomal recessive disorder associated with impaired metabolism. Accompanied by various deviations in the development of the child, mental retardation and other manifestations.
7. Triploidy. This is the most common genetic anomaly. With this syndrome, the fetus has not two, but three chromosome sets. There are many defects in development.

What is a blood test for screening?

A blood test is a mandatory component of screening during pregnancy. It is necessary for assessing the state of the placenta, determining the level of hCG - a hormone, a low value of which indicates problems with the placenta, and high - that there is not one fetus in the uterus, but two or more, or a chromosomal disorder occurred in the child.

In addition, a test is performed for the presence of protein A. Its low level signals the risk of a disorder in a series of chromosomes, and a high level allows judging of pathologies such as Edwards syndrome and Down syndrome.

It also determines the amount of the hormone-estriol produced by the placenta during pregnancy, its shortage indicates violations in the formation of the fetus.A study of the blood of a pregnant woman will allow you to determine the amount of AFP protein, when exceeding the norm, you can judge the congenital abnormalities of the fetus, while decreasing - about Down syndrome. A significant increase in protein in most cases causes fetal death of the child.

But even the negative results of the study do not allow one hundred percent to assert that the child will have abnormalities, since the determination of the formation of the fetus is carried out comprehensively, and the values ​​of individual tests are only the result of taking certain medications or hormone-containing drugs. For this reason, if the screening showed high risks of abnormalities in the fetus, it is necessary to go to the reception to the genetics. The specialist will be able to determine whether there is a risk for the baby.

Such a step as blood donation should be taken only after an ultrasound examination has been performed. This is very important because each value is influenced by the duration of the pregnancy. Role plays every day. Daily there is a change in the values ​​of the norm. And ultrasound helps to determine the period with maximum accuracy.At the time when blood will be donated for tests, it is necessary that the data obtained during the ultrasound examination be ready, they must include the fetal CTE and the calculated duration of pregnancy. In addition, an ultrasound examination may reveal that the pregnancy is frozen, which means that it will be pointless to be examined further.

How to prepare for blood donation for screening

As a biomaterial for screening, only venous blood is used. The procedure is carried out necessarily on an empty stomach in the morning. It is not recommended to use clean water before giving blood. This can be done only if the analysis is submitted very late. It is highly undesirable to violate this condition, because of this, the results may be unreliable. It is preferable to eat immediately after the procedure.

A couple of days before the study, it is necessary to abandon the use of allergen-based products, even if previously no allergic reactions were observed. These products include chocolate, nuts, citrus fruits, whole milk. You should also remove from the diet fatty, smoked, spicy, salty foods.If you do not adhere to these rules, the risk of obtaining incorrect data will increase significantly.

The indicators that are considered in the blood test:

1. HCG The hormone chorionic gonadotropin is produced by the shell of the fetus. According to the level of this hormone, it is possible to determine if there is a pregnancy within a couple of weeks after conception. During the entire first trimester of pregnancy, the value gradually increases. The peak of its growth is noted closer to the twelfth week. Then there is a gradual decrease.
2. PAPP-A. This protein is produced by the placenta during pregnancy. Responsible for the immune response during this period, as well as the proper formation and operation of the placenta.
3. MoM coefficient. When the results of the study are received, the doctor will analyze them, taking into account the IOM coefficient. This value indicates abnormalities. The normal level is from 0.5 to 2.5, if in the womb, not one, but several children - 3.5.

The values ​​of the coefficient and norms may vary in some medical institutions. It happens that the amount of protein is calculated in different units.Therefore, you should not try to decipher the results of the analysis yourself; only a competent specialist should do this.

Then, the values ​​obtained during the study are entered into a special program, and the rest of the information regarding the patient's condition and health is entered here - age, weight, presence of bad habits, chronic diseases, single pregnancy or multiple pregnancy, natural or not (IVF). Based on the results calculated by the program, the risk of the presence of possible genetic malformations is determined. About increased risk can be judged if the figures are less than 1: 380.

In some cases, indicators may differ; this must be taken into account when evaluating results. So, the indicators will be different if:

• Woman suffers from obesity.
• Pregnancy is multiple.
• The future mother is diagnosed with diabetes.
• Pregnancy occurred with in vitro fertilization (IVF).

Screening study for multiple pregnancies

At the end of the first trimester, using ultrasound, you can determine how many fetuses are in the uterus of the mother. If there are several, the pregnancy is called a multiple pregnancy.For her in the future is carried out more thorough control. This means that diagnosing the state of the body of a pregnant woman and children is more frequent.

First of all, this applies to ultrasound, since such a study allows a specialist to better examine the organs of the pregnant woman and to exercise full control over the formation of fetuses. If there are any deviations in development, the doctor will find them in time.

It is necessary or to undergo screening during pregnancy: pros and cons

It is imperative to conduct a screening study if a pregnant woman is over 35 years old, and 45 years old for the father of a child, and also when someone has a hereditary disease in a mom or dad. In addition, it is necessary to undergo the procedure if in the past a woman suffered one or more miscarriages, and also if she had a child with congenital or chromosomal pathologies before. The doctor will insist that the expectant mother do this procedure if, before the conception occurred, she or the father of the child were exposed to radiation.

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