Minimizing the risk of amniocentesis for prenatal diagnosis.

Although the risk of amniocentesis in the second trimester of pregnancy is small, untoward sequelae can be further reduced. One hundred twenty amniocenteses were attempted during a two-year period. In eight instances, the patient had to return for a second tap because of bacterial contamination, inadequate number of fetal cells, or inability to obtain amniotic fluid. These eight patients all underwent repated amniocentesis and successful karyotyping. There were no major complications and one minor complication. Two spontaneous abortions were not apparently related to the procedure. In both these cases, fluid could not be obtained because one patient had a blighted ovum with a small sac and the other had large uterine fibromyomas.