Amniocentesis is an invasive procedure consisting of a puncture of the amniotic membrane in order to obtain amniotic fluid for subsequent laboratory examination, amnioreduction or the introduction of drugs into the amniotic cavity. Amniocentesis can be performed in the first, second and third trimesters of pregnancy (optimally - in 16-20 weeks of pregnancy). This procedure is necessary for the early diagnosis of chromosomal and genetic diseases in the fetus.
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Classification of Amniocentesis
By time :
- early amniocentesis: performed in the first trimester of pregnancy (from 8 to 14 weeks);
- late amniocentesis: performed after the 15th week of pregnancy.
By access technique :
- using a puncture adapter;
- free-hand method.
Indications for amniocentesis
- Prenatal diagnosis of congenital and hereditary diseases. Laboratory diagnosis of congenital and hereditary diseases is based on the cytogenetic and molecular analysis of amniocytes.
- Amnioreduction (with polyhydramnios).
- Intraamnial administration of drugs for abortion in the second trimester.
- Assessment of the fetus in the second and third trimesters of pregnancy (severity of hemolytic disease, maturity of lung surfactants, diagnosis of intrauterine infections).
- Fetotherapy.
- Fetosurgery.
Contraindication to amniocentesis
An acute process or exacerbation of chronic inflammation of any localization.
Fever in a pregnant woman;
Myomatous nodes of large sizes.
The threat of miscarriage and detachment of the placenta;
Amniocentesis Technique
Under ultrasound control, the puncture site is selected. The puncture is preferably performed extracentrally, in the largest pocket free of umbilical cord loops. If the needle must be inserted transplacentally, choose the thinnest section of the placenta that does not have expanded intervillous spaces. Amniocentesis is performed using needles having a diameter of 18-22G. Technically, amniocentesis is performed using the βfree handβ method or using a puncture adapter placed on a convex abdominal sensor. Its use allows you to control the trajectory of movement and the depth of immersion of the puncture needle using the track on the monitor screen. After making sure that the needle after the puncture is located in the cavity of the fetal bladder, mandrin is removed from it, a syringe is attached and the required amount of amniotic fluid is aspirated. After that, the mandrin is again placed in the lumen of the needle and removed from the uterine cavity. After the procedure, the fetus is assessed (the presence and frequency of its heartbeat). When performing amniocentesis in the third trimester of pregnancy, it is recommended that monitoring be performed on the fetus. According to the indications, maintenance therapy, intraoperative antibiotic prophylaxis and / or therapy are carried out.
Complications of amniocentesis
- Premature discharge of amniotic fluid.
- Short-term leakage of a small amount of OM is possible during the first days after surgery (in 1-2% of cases).
- Detachment of the membranes.
- Infection (the most unfavorable in relation to infection is the second trimester of pregnancy due to the low level of antibacterial activity of amniotic fluid).
- Wounding the vessels of the umbilical cord or the fetus itself;
- The development of alloimmune cytopenia in the fetus.