Amniocentesis
January 20, 2009
Amniocentesis is a tool that helps to know more about the development of a foetus. The amniotic sac is a fluid filled structure inside the pregnant woman’s uterus. This is where the baby lives. The foetal cells, proteins and foetal urine, move freely in this area. Amniocentesis involves taking a small portion of the amniotic fluid, which surrounds the foetus. This way along with the fluid, these cells also come, which can be examined.
This sample is then examined to check for genetic defects, infections or for foetal maturity.
Who can go for an amniocentesis?
Anything that causes the doctor to suspect the normal development of the foetus will call for an amniocentesis. It can be age, prior history, an abnormal foetus seen during the ultrasound or an abnormal triple screen.
What does the procedure involve?
A pocket of fluid is localised. First, the doctor prepares the abdomen of the patient so that sterility is maintained. Then, using a long, thin-bore needle, approximately 30 cc of amniotic fluid is removed. The doctor may or may not use local anaesthesia. This is done under ultrasound guidance.
However, there is no need to worry because during pregnancy there is about 150-300 cc of amniotic fluid and it is regenerated. Hence, the baby does not endure any discomfort. The fluid is then put in tubes, which are placed in centrifuges. These separate out the foetal cells so that they can be examined.
Level of alpha-fetoprotein, which is a protein of the foetal liver, is measured. If it is high, then it indicates that the foetus has spina bifida, a defect in the brain and spinal cord development. However, too low level indicates the possibility of Down’s syndrome. If such is the case, then further tests are conducted to look for birth defects and chromosomal abnormalities.
What is the significance of the test?
This test can also be carried out to know any genetic and chromosomal abnormalities in the foetus. Disorders like Tay-Sachs disease, cystic fibrosis, sickle cell anaemia and other inherited disorders can be recognised using this technique.
Rh incompatibility can also be identified using this technique.
Are there any risks involved?
There is a small chance that the foetus may incur an infection or injury. There is also a small chance of miscarriage. However, this test is performed only if the doctor suspects any problem. Hence, the benefits of the test are far more than the risks involved.





























