Amniocentesis is done to detect any chromosome abnormalities in the fetus. It is a diagnostic test and is usually performed during the pregnancy. It is a very useful test as it can detect any possible chromosome abnormality that can lead to the many serious congenital diseases like Down's syndrome. In this procedure a sample of the amniotic fluid surrounding the fetus is removed and analyzed.

 

This test is performed only after crossing week 14 of the pregnancy. A preliminary result may be available within 48 hours and the final result will be known in two to three weeks. Amniocentesis carries a slight risk of miscarriage. Every 1 in 100 - 200 amniocentesis procedures will lead to a miscarriage, usually within three weeks of the procedure. Before going for the procedure a women should be given enough space to ask about any query she is having regarding the procedure and the risks involved, also she should be told in detail regarding the procedure so that she can compare between the risks involved in the procedure and the benefit of  the early detection of some chromosomal abnormality. Very few things in life are guaranteed 100 per cent reliable. Amniocentesis comes very close, with a certainty of 99.9 per cent in identifying chromosome abnormalities. There is no treatment for chromosome abnormalities. If a diagnosis is made before birth, and depending on the nature of the abnormality that has been detected, the woman will generally be offered a termination of pregnancy. The decision whether or not to continue with the pregnancy always rests with the parents and some parents may decide to continue. Therefore it is to be considered before the procedure that the impact test can make on the decision of the parents.

Criterion for Amniocentesis

Following women are considered for the test - 

• Women who are at high risk is calculated by the levels of pregnancy hormones in the blood combining with mother's age. Using these parameters the risk of the fetus getting Down's syndrome can be calculated.
• History of chromosomal abnormality in previous pregnancy
• Amniocentesis can be advised if ultrasonography detects any abnormality or if any abnormality is suspected.
• Amniocentesis is also done on request of the woman.
• Amniocentesis is advisable for the investigation and management plan of the rhesus disease

Procedure of Amniocentesis

Under the guidance of Ultrasound, a fine needle is inserted through the mother's abdomen into the fluid surrounding the fetus. About 20ml of the amniotic fluid is aspirated and sent to a laboratory for analysis. The procedure generally takes 5 to 10 minutes and the mother will feel only slight discomfort. The fetus will remain unaffected due to the procedure.

After the procedure, the mother should rest for the day. She may feel slight cramping. Bleeding and leaking of fluid from the vagina is not normal and she should contact the hospital if this happens.