Amniocentesis

Amniocentesis, procedure of sampling the amniotic fluid surrounding a fetus by puncturing the abdomen of the pregnant woman with a very fine, hollow needle. Cells and other substances shed into the amniotic fluid by the fetus are used for detecting the presence in the fetal genes of such disorders as Down's syndrome, Tay-Sachs disease, and spinal malformations. Amniocentesis also can be used to determine the sex of an unborn child with 98% accuracy.

See also: Genetic counseling.