Neural tube defects: issues in prenatal diagnosis and counselling.

Neural tube defects are a heterogeneous group of malformations resulting from failure of neural tube closure during early embryogenesis. They range widely in severity from the lethal condition of anencephaly, to severely disabling meningomyeloceles, to completely surgically correctable meningoceles. Occurring in 1.4 to 1.6 per 1000 live births, neural tube defects rank second only to cardiac abnormalities as a cause of major congenital malformations in the United States. Technical developments over the past decade have enabled better detection of these conditions prenatally. Understanding of the etiology, neonatal treatment, and potential prevention of neural tube defects is increasing. Further, the ethical issues of treatment and screening are being widely discussed in both news magazines and the Congressional Record. Thus, it is timely to review this important area of prenatal counselling, diagnosis, and management.