RANDOMIZED TRIAL TO DETERMINE OPTIMAL DOSE OF VAGINAL MISOPROSTOL FORPREABORTION CERVICAL PRIMING

Objective: To determine the optimal dosage of vaginal misoprostol for cervical priming before vacuum aspiration abortion. Methods: One hundr ed twenty women were assigned randomly to receive 200, 400, 600, or 80 0 mu g of misoprostol given vaginally. Vacuum aspiration was performed 3-4 hours after the insertion of misoprostol tablets. The degree of c ervical dilation before operation was measured with a Hegar dilator. P reoperative and intraoperative blood loss and associated side effects also were assessed. Results: Twenty-nine (96.7%) women in the 400-mu g group and all in the 600-mu g and 800-mu g groups achieved cervical d ilation of at least 8 mm. The success rate for the 200-mu g group was only 23.3%, significantly less efficacious than the 400-mu g dose (odd s ratio 95.3; 95% confidence interval 10.9, 830.9; P < .001). There wa s no significant difference among the 400-, 600-, and 800-mu g groups (P = .364) with respect to achieving cervical dilation at least 8 mm. However, 800 mu g was associated with significantly more side effects than 600 mu g (preoperative and intraoperative blood loss, P < .001; a bdominal pain, P = .005; products of conception at os, P <.001; fever higher than 38.0C, P = .002). When 400 mu g and 600 mu g were compared , we found that the higher dose also was associated with significantly more side effects. The 600-mu g group was used twice in the compariso n, but all P values remained significant even after the Bonferroni adj ustment for multiple comparisons. Conclusion: Vaginal application of 4 00 mu g of misoprostol is the optimal dose for vacuum aspiration preab ortion cervical dilation in first-trimester nulliparas. (Obstet Gyneco l 1998;92:795-8. (C) 1998 by The American College of Obstetricians and Gynecologists.)