Amniocentesis
During the early days of pregnancy, amniocentesis is carried out on pregnant woman to find out if the developing fetus is free from certain abnormalities. This procedure involves certain invasive methods like inserting a hollow needle into the uterus of the woman through her abdominal wall to withdraw a sample of amniotic fluid that surrounds the fetus. Using ultrasound, the location of the fetus floating in the amniotic fluid is determined. The abdominal skin surrounding the area is cleaned. The procedure may be conducted either by injecting a local anesthetic in that area, or by just applying a tropical anesthetic around the area through which the needle is to be inserted. About 1 cc per week of gestation of the fetus is taken out from the amniotic fluid.
This procedure is used as a tool which can detect chromosomal disorders like Downs Syndrome and many rare metabolic disorders which are normally inherited. Some structural defects like spina bifida and anencephaly can be detected using this test. This procedure is normally carried out for women over the age of thirty five. It is recommended for women who had undergone a triple screen blood test during pregnancy and for those who have a family history of birth defects or some inherited metabolic disorders. This procedure may be conducted even in later stages of pregnancy to detect suspected problems like Rh incompatibility or infection. This test is also used to determine lung maturity of the infant in the last trimester.
A cell culture is done with the fetal cells taken out during the procedure and the analysis of the DNA is conducted to detect chromosomal abnormalities. It may take up to a month for the results to arrive. This is rated as a highly accurate procedure.
After the withdrawal of the amniotic fluid which takes only a few minutes, the pregnant woman is advised to be in bed for several hours, though the entire procedure will last for about 45 minutes. Doctors check the heart beat of fetus to ensure that it is normal. It is wise to call the health care provider, if the woman experiences fever, bleeding or leakage of amniotic fluid for a long time. Though the chances of infection or injury to the fetus are not ruled out, they are quite rare. There is also a slight chance of miscarriage, but the percentage is negligible. During later stages of pregnancy, a Doppler ultrasound is safer than amniocentesis because it is non-invasive. Anemia in the fetus can easily be detected using ultrasound by measuring the velocity of the blood flow in the middle cerebral artery.
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