Risks of fetomaternal hemorrhage resulting from amniocentesis with and without ultrasound placental localization.

The incidence of multiple abdominal punctures, blood-stained aspirates, and fetomaternal transfusion was compared in patients undergoin amniocentesis at various stages of pregnancy with and without prior placental localization by ultrasound. A lower incidence of complications was found in those on whom ultrasound examination had been performed.