Methods of prenatal diagnosis

Ultrasound examination

At present, for the additional examination of a pregnant woman, the most widespread distribution has been a simple and accessible ultrasound method - ultrasound. His undoubted advantages are safety, absence of any additional training, almost complete absence of contraindications. To a woman with a normal pregnancy, ultrasound is performed three times:

1) at the 11-13 weeks gestation period;

2) for a period of 20 weeks;

3) for a period of 32 weeks.

This examination is conducted to identify the defects of intrauterine development. It is especially important to conduct this study in the early stages, when the laying of the main organs and systems takes place. If a serious pathology is detected, it will be possible to have an early abortion.

If there are additional indications, ultrasound can be performed at an earlier time, up to 12 weeks of pregnancy. In certain situations, the need for a more frequent examination increases:

1) if a woman has a disease( diabetes mellitus, hereditary diseases, neurological disorders, alcoholism, etc.) that multiply the risk of a child with intrauterine malformations;

2) the presence of a weakened obstetric-gynecological history, the birth of a child with

with intrauterine malformations from a previous pregnancy;

3) in cases where pregnancy occurs with various complications, both in the first and second half;

4) if there is a delay in intrauterine development of the fetus;

5) in the presence of congenital malformations in the spouses, as well as with relatives of 1-3 generations on both sides;

6) when exposed to the body of a woman of harmful factors( viral diseases, radiation, taking certain medications, etc.) in the early stages of pregnancy;

7) the presence of elevated serum levels of alpha-fetoprotein at the 17th week of pregnancy.

Ultrasound examination allows revealing the pathology of various organs and systems: mochevidelitelnoy, digestive, cardiovascular, nervous systems, musculoskeletal system.

Possible detectable pathology: 1) from the nervous system: microcephaly( small brain) or complete absence of the brain, spinal hernia, abnormal development of the bones of the skull, splitting of the vertebral bodies;

2) from the gastrointestinal tract: defects in the anterior abdominal wall or its complete absence, infection of the lumen of the duodenum, infection or complete absence of the esophagus;

3) from the side of the urinary system: a violation of the normal structure and number of kidneys and ureters, adhesion of the kidneys, polycystosis( poly - many, cyst - bubble with fluid) of the kidneys;

4) from the side of the cardiovascular system: combined and isolated malformations are possible: absence of large vessels, a two-chambered heart;

5) from the musculoskeletal system: abnormal development, partial or complete absence of limbs.

Despite the safety of the method, it is still not recommended to perform ultrasound once again, since the effect of the echo signal used in this examination on the fetus is only being studied.

Analysis of the blood of a pregnant woman for the content of the alpha-fetoprotein

Alpha-fetoprotein is a protein necessary for the normal development of the fetus.

The determination of its quantity is of diagnostic significance: an increase in the concentration of this protein indicates a possible pathology of the dissection from the side of the nervous system, the anterior abdominal wall. Reduction can be observed in the presence of Down's syndrome in the fetus, so women who are at risk of having a child with such a pathology, it is necessary to determine the content of this protein in the blood.

There are no medical contraindications for the determination of alpha-fetoprotein to the blood of a pregnant woman. With a lower concentration of this protein, it is desirable to carry out a cyto-genetic( "cyto" -cell) study of fetal cells, and at a higher concentration, to determine the content of the amniotic( amniotic fluid).You should also perform ultrasound examination of the fetus.

Amniocentesis

Amniocentesis is a diagnostic procedure in which a fetal bladder puncture is performed to produce amniotic fluid. Obtained amniotic fluid, as well as the cells of the fetal membrane contained in it, undergo biochemical and cytogenetic studies.

Procedure is performed after preliminary ultrasound examination. This is necessary for:

1) clarification of the gestational age;

2) the exact location of the placenta;

3) elimination of malformations of the fetus and uterus;

4) warnings of polyhydramnios. Amniocentesis in Russia is used already more than

for 30 years and represents one of the most important methods of prenatal diagnosis. It is best to perform it at the gestational age of 16-18 weeks, since it is during this period in the amniotic fluid that a large number of cells are needed for the study. In addition, if there are certain indications, it will be possible to repeat the procedure after a certain time.

With this study, you can determine the sex of the fetus and identify some hereditary pathology, for example, metabolism.

Chorionic villus analysis

Chorionic villus analysis( chorion biopsy, placenta biopsy) is a diagnostic method by which chorionic villi and placenta are taken for examination. This method of diagnosis is very important, as it allows to diagnose a large number of hereditary diseases at an early pregnancy. The most optimal time for this procedure is the period from the 8th to the 16th week of fetal development.

The procedure is performed under the supervision of ultrasound.

Chorionic villus and placenta villus analysis can be performed in two ways:

1) through the front abdominal wall;

2) through the cervix.

The following complications occur during the examination:

1) minor bleeding;

2) entry into the uterus of the infection, as a result of which the inflammatory process develops, this complication is very rare;

3) reduction of the uterine musculature, which is observed in 2% of cases;

4) spontaneous abortion, this complication develops in 1.5% of cases.

Chorion biopsy is recommended to be performed no earlier than the 8th week of pregnancy.

Cord blood analysis

Cord blood analysis is performed under the supervision of ultrasound. The most optimal period for performing this procedure is the gestation period from 18 to 22 weeks. The blood obtained from the cord is subjected to various studies: cytogenetic, biochemical, molecular genetic. The results of the examination are ready in 72 hours. This is the advantage of this method of analysis in comparison with the study of cells of the amniotic fluid, for which this period is many times longer.

Cord blood analysis allows to diagnose numerous diseases:

1) immunodeficiency conditions of the fetus;

2) hereditary blood diseases: thrombotic cytopathy, impaired activity of the blood coagulation system, hemoglobinopathy, etc.;

3) chromosomal diseases;

4) blood condition in the presence of Rh-conflict;

5) presence of intrauterine infection.