Preparing For Genetic Amniocentesis

Doctors typically encourage a formal counseling session - not just a short discussion in the doctor's office - before parents decide about genetic amniocentesis. In the counseling session, parents can weigh the benefits against the modest risk from the procedure. They can also discuss specific gene or chemical tests that family and maternal histories may warrant. Parents may consult a genetic counselor, who is trained to identify potential risk factors and suggest specific tests.

Genetic amniocentesis is normally performed between the 15th and 17th week of pregnancy because the amount of fluid bathing the fetus doubles in volume between 14 and 16 weeks of gestation.

A woman does not have to prepare for amniocentesis in any special way, such as by keeping her bladder full or fasting beforehand. However, she should avoid strenuous activity for the rest of the day following the procedure.

Most test results will be available within about 3 weeks. Much of that time is devoted to growing the small amount of cells found in the amniotic fluid. Since the rate of cell growth varies, sometimes results take longer. The doctor will be called immediately if the tests reveal an abnormality.