Amniocentesis for prenatal diagnosis

Reema got married very late. And by the time she was ready for a child, she was 35 years old. Since she was aware of problems that could arise from a late pregnancy, she consulted her gynaecologist about tests she could go through that would assure her that her baby is normal and healthy.

One of the tests, Amniocentesis (also referred to as amniotic fluid test or AFT) gave her a lot of information about the fetus.

A little of her amniotic fluid was removed from her uterus and analysed for possible foetal abnormalities. It was done between the 12th and 16th week of pregnancy and was completely painless.

This test is performed only if it is absolutely necessary; if other tests point towards abnormalities in the child. Since there is always a tiny risk of miscarriage after this test. An area of skin on the front of the abdominal wall is treated with a local anaesthetic and a needle is gently introduced into the cavity of the uterus to withdraw a small quantity of fluid. It is done after an ultrasound scan to avoid injury to the baby and to minimise complications.

A large number of congenital abnormalities can be detected, including Down’s Syndrome (chromosomal disorder) and spina bifida. Spina bifida is a congenital anomaly where the vertebral bones of the spine do not fuse so that the meninges (the covering on the brain and spinal cord) bulge at some points in the spinal column. It may contain nerve roots, or the spinal cord itself may be exposed. This condition could lead to meningeal infection due to the absence of the various coverings that normally protect the spinal cord.

The incidence of spina bifida is now fortunately reducing due to careful monitoring by special tests like Amniocentesis and better knowledge of the importance of folic acid before conception and in early pregnancy. Spina bifida can be detected by ultrasound and the baby can be sent for special surgery without delay. However, the overall prognosis is poor for babies with severe defects. Problems may include complete paralysis of the legs, incontinence of urine and faeces and mental retardation.

The sex of the baby can also be determined by examining the cells in the amniotic fluid. Unfortunately this test is being misused to detect the sex of the baby and to abort female fetuses, and is illegal.

In some instances of polyhydramnios (a condition where the amount of amniotic fluid is more than normal), amniocentesis is performed to remove some fluid in order to relieve pressure within the uterus.