Biochemical screening - what kind of analysis is this?

The future mother during all period of bearing of the kid should pass a lot of various diagnostic researches with the purpose of the control over a state of health of the woman and its fruit. Some tests are mandatory, while others are recommendatory. That is biochemical screening. What this is, what is done and what pathologies can be detected with its help, we consider in the article.

What is biochemical screening during pregnancy?

This method of diagnostic research has become widespread in medical practice quite recently. Initially, it was carried out exclusively according to the doctor's indications for the purpose of early diagnosis of certain genetic pathologies. But thanks to the availability and effectiveness of this method began to be used in preventive studies. Now, a pregnant woman without special medical evidence can pass this test at will.

So, biochemical screening - what is it? This is an analysis of venous blood for the purpose of determining chromosomal pathologies. But the results of screening can not be a definitive diagnosis, with 100% accuracy using this method it is impossible to confirm the presence of a chromosomal disease. Only the probability of such pathology is determined in each specific case.

In order to properly interpret the results of biological analysis, just before taking blood, the pregnant woman is sent for ultrasound examination. So, on ultrasound the doctor makes measurements of the fetus, assesses its condition. Deviations from established norms, together with high indicators of biochemical blood test results, may indicate the presence of a genetic pathology in the fetus. If a high level of probability is found for the fetus of a chromosomal disease, specialists can recommend going through additional diagnostic procedures. For example, in this case, doctors can prescribe an intrauterine study of the material in order to establish a definitive diagnosis.

Thus, only the probability of having a chromosomal pathology determines biochemical screening. What is this analysis, how to conduct it, we find out later in the article.

Indications for screening

As stated above, the study is conducted for both preventive and clinical purposes. Mandatory screening is in such cases:

• If the married couple are close relatives;
• A pregnant woman suffered an infection shortly before pregnancy and immediately in the specified period;
• In the anamnesis there was a frozen pregnancy, stillbirth, miscarriage, premature birth or the birth of children with genetic abnormalities;
• In the family there are relatives with chromosomal diseases;
• The age of the future mother exceeds 35 years;
• The pregnant woman took medications prohibited during the period of the child's birth, or was exposed to radiological as well as radiation radiation;
• Shortly before conception, the future father or mother underwent radiation therapy or radiological examination;
• The results of an ultrasound study of a pregnant woman are questionable, and perinatal biochemical screening is recommended (which is dangerous for a pregnant woman such a study, the doctor will tell in detail).

What determines the analysis?

Biochemical screening is performed two or three times throughout the pregnancy. And depending on the term, it diagnoses various chromosomal abnormalities in the fetus:

• Edwards syndrome;
• The Patau syndrome;
• Down syndrome;
• Lange syndrome;
• Presence of neural tube defect.

The first three diseases have such a common name, like trisomy. To determine early on such anomalies of chromosome connections helps doctors to biochemical screening. What are these pathologies, what are dangerous? In the presence of trisomy during the biochemical analysis of the pregnant woman's blood, laboratory workers detect 22 pairs of normal chromosomes and one "triple" pair. Depending on where the pathology was formed, the diseases are differentiated.

First trimester screening

In medical practice, often resort to such an analysis as a biochemical screening of the first trimester. What is it, what is needed and when is it conducted? For the first time a pregnant woman is faced with the concept of screening at a period of 11-14 weeks. Such an examination includes ultrasound, in which the doctor measures the collar space of the fetus, clarifies the gestational age and the PDR.

After the ultrasound, the woman is referred by a doctor to a blood test. At this stage, the human chorionic gonadotropin and the PAPR protein are determined. Based on the results obtained, specialists may suspect violations in the development of the fetus, including detecting a chromosomal pathology, such as Down's syndrome.

Another name for "double test" is biochemical screening for the first trimester. What it is? The study at the 11-14th week of pregnancy acquired this name due to the fact that a blood test is performed for two specific substances: hCG and PAPR protein.

Norms for first trimester screening

The indicators of hCG and RAPP are influenced by external factors, such as the weight of the pregnant woman, the terrain and climate of the territory of residence, the length of pregnancy, and others. In order to adapt the norms, such units of measurement as MoM were developed for most women. The norms of biochemical screening are calculated in such units. In order to calculate them, the obtained results of a pregnant woman's blood test are divided by the norm values established for a specific locality, term and weight category of women. Thus, if the result is 0.5-2.5 MoM, the hormone is within the normal range. But above 2.5 MoM indicates a high risk of chromosomal pathologies.

Second trimester screening

Biochemical screening for the 2nd trimester is scheduled: what is it and why is it necessary to undergo such examination? The second screening may be scheduled for a period of 16-18 weeks. During such a comprehensive examination, ultrasound diagnostics will be performed, if necessary in a 3D format, during which the doctor will measure the fetus, assess its heart rate and position in the uterus.

A blood test will be performed to determine three or five hormones, such as: hCG, RAPP, estriol, placental lactogen and inhibin. Such an analysis is called a triple test.

If necessary, the future mother can be sent to a consultation with a geneticist who will evaluate the results of screening for the second trimester and give recommendations.

Third trimester screening

Screening in the third trimester is most often performed according to the doctor's indications at the 32-34th week. During an ultrasound examination during this period, the doctor evaluates the development of the child's internal organs, his presentation, the presence or absence of a cord with the umbilical cord, the condition of amniotic water and the placenta. Blood is analyzed by triple test.

Features of the third trimester screening are additional diagnostic studies in the form of Doppler and CT. With the help of the first procedure, blood flow is assessed and fetal hypoxia is determined. And the second one defines violations in the work of the heart. These procedures are conducted in the same way as ultrasound, being absolutely safe and painless for a pregnant woman and her child.

Preparation for screening

The doctor recommended to undergo biochemical screening? How to take the test to get the correct results? Proper preparation for screening is an important component that determines the reliability of the results obtained. So, for example, if the recommendations on nutrition in the process of chemical reactions are not observed, the laboratory technicians will receive only a fat mass, from which it will be difficult to determine anything. Therefore, one day before perinatal screening at any time of pregnancy, you should not use such products:

• Spicy food;
• Smoked products;
• Fatty and fried;
• chocolate;
• Black strong tea and coffee;
• Citrus fruits.

Rent blood on an empty stomach.

Conducting the analysis

Screening usually takes place in two stages. The first involves ultrasound examination. Only after receiving the results of ultrasound, you can go to a blood test. Usually the results of biochemical screening can be obtained only after a sufficiently long time - from one and a half to three weeks. In private clinics, it is possible to conduct the analysis in accelerated terms - up to a week.

Is screening for pregnant women mandatory? Screening is a recommended examination of a pregnant woman. On the one hand, thanks to this simple and safe study, one can detect serious pathologies of the baby's development in the early stages. But at the same time, the diseases defined in this way are not amenable to treatment. In addition, the results only indicate the degree of risk of developing disorders and are not a diagnosis. When a deviation is detected, the future mother becomes confronted with a complex choice of further development of pregnancy. Therefore, the final decision on the passage of such a survey can only be taken directly by future parents.

Explanation

The interpretation of biochemical screening presupposes the availability of professional knowledge. Only the attending physician can interpret the results. It is important to take into account and compare various factors, compare norms, assess predisposition to genetic diseases.

The analysis of the blood is deciphered in this way:

• 1:10 000 is a low risk of developing pathologies;
• 1: 1000 - the average;
• 1: 380 - high, which requires additional studies.

Ratios indicate how many pregnancies a case of pathology may be. That is, for example, at a low risk, the probability of developing a chromosomal disorder is 1 per 10,000.

Patient Reviews

Pregnant women are looking forward to seeing their baby on ultrasound. But at the same time, such a survey brings many experiences. Often, the screening factors are influenced by external factors, and during the re-examination the deviations do not find their confirmation. But during this time the future mother is experiencing serious fears associated with the unknown and the identified danger, which has a very negative impact on her condition and the development of crumbs.

That is why patients' reviews about the innovative diagnostic method are ambiguous. Some are confidently going to the examination with the purpose of early detection of violations of the child's development, others refuse on moral and spiritual views.

Cost of Screening

Another factor that contributes to the failure of future mothers from perinatal screening is its cost. Only in the case of referral and examination in a state polyclinic or hospital, the analysis may be an insurance event.

If the screening is done at will for preventive purposes or in a private clinic, you will have to pay from 5000 to 9000 rubles, depending on the clinic and the equipment used in it.

In this article, we examined what it is important to undergo biochemical screening, what it is, how it is conducted, what evidence it has. The decision about whether or not to undergo such a study should be taken by a pregnant woman in conjunction with a doctor. And most importantly, tune in to a positive result and a reasonable evaluation of the responses of the analysis.