Amniocentesis carried out for neural tube indications in South Wales 1973-1981: outcome of pregnancies and findings in the malformed abortuses.

The 2872 second trimester amniocentesis followed by amniotic alphafetoprotein (AFP) estimations carried out in South Wales between 1973 and 1981 on women known to be at increased risk for neural tube defect (NTD) and those who had a raised serum AFP level in an NTD screening programme led to the identification of 78 pregnancies of a fetus with anencephalus, 61 with 'open' spina bifida, 8 with gastroschisis, 3 with exomphalos, 2 with encephalocele and 6 with chromosome abnormality. Pregnancies of fetuses having 4 potentially identifiable NTDs were missed because of an equivocal AFP level and there were two false positive results leading to the termination of one normal fetus. It is emphasized that both the latter problems of one normal fetus. It is emphasized that both the latter problems would not have occurred had gel-electrophoresis for isoenzymes of acetyl cholinesterase been available. Follow-up of pregnancies showed that 7 children with 'closed' NTD and 3 with congenital hydrocephalus were born. The anencephalic and the 'open' spina bifida had a more florid lesion than is usual at term. Nearly all the spina bifida were associated with hydrocephalus, often severe and with an obvious Arnold-Chiari malformation. All but 13 had leg or back deformation or malformations in other systems, mostly in the renal tract.