Induction of midtrimester abortion with intra-amniotic urea and intravenous oxytocin

Midtrimester abortions were induced in 295 patients with a combination of intra-amniotic urea and intravenous oxytocin. The mean injection-abortion interval was 26.4 hours. Abortion occurred spontaneously within 50 hours of amnioinfusion in 257 patients. The macerating effect of the hypertonic urea on fetal tissues allowed easy termination of the remaining 38 pregnancies by suction curettage at 50 hours after injection. Decreased urinary output occurred during the oxytocin infusions, but water intoxication was prevented by close monitoring of urinary output and serum electrolytes, and by the use of a concentrated solution of oxytocin in normal saline, allowing the administration of small volumes.