Prenatal diagnosis of genetic disorders.

One of the most significant advances in medicine is the development of prenatal diagnosis. In many circumstances it is now possible for the physician to learn definitively whether or not a fetus has a given genetic disorder. If the fetus is found to be affected, the couple may elect termination of the pregnancy. The most widely used technique for prenatal diagnosis is midtrimester amniocentesis, which permits chromosomal or enzymatic studies of amniotic liquor and cultured amniotic fluid cells. Recent advances in DNA analysis of amniotic fluid cells have opened new vistas for the antenatal detection of hemoglobinopathies, and potentially, for other genetic disorders. Advances in ultrasonography have not only made amniocentesis safe and more reliable, but have also offered new opportunities for the detection of certain defects. Finally, in addition to allowing direct fetal visualization, fetoscopy has permitted access to fetal tissues (e.g., blood, skin), thereby making feasible the diagnosis of disorders not otherwise detectable.