Evacuation interval after vaginal misoprostol for preabortion cervical priming: A randomized trial

Objective: To determine the optimal interval for evacuation after preaborti on cervical priming with vaginal misoprostol. Methods: One hundred eighty healthy nulliparas requesting legal termination of pregnancy between 6 and 11 weeks' gestation were assigned randomly to r eceive 400, 600, or 800 mu g of intravaginal misoprostol. Vacuum aspiration was done after 3 hours in the 400-mu g group and after 2 hours in the 600- and 800-mu g groups. The degree of cervical dilatation before operation wa s measured with a Hegar dilator. Preoperative and intraoperative blood loss and associated side effects were also assessed. Results: Eleven (18.3%) and 15 (25.0%) women in the 600- and 800-mu g group s, respectively, had cervical dilatation of at least 8 mm after an interval of 2 hours; 55 (91.7%) women who received 400 mu g for a 3-hour interval h ad similar cervical dilatation. Using 400 mu g as a baseline, the odds rati o (OR) was 0.02; 95% confidence interval (CI) was 0.01, 0.06 for 600 mu g a nd OR 0.03; 95% CI 0.01, 0.09 for 800 mu g for achieving successful preabor tion cervical dilatation of at least 8 mm. The mean cervical dilatation of 6.7 mm and 6.8 mm for the higher doses was also significantly less than tha t of 8.1 for the 400-mu g dose (P < .001). The mean preoperative and intrao perative blood loss was only statistically different when the 400- and 800- mu g groups were compared (P = .03). There were also significantly more sid e effects, namely abdominal pain and fever above 38.0C, in the 600- and 800 -mu g groups (P < .001), compared with the 400-mu g group. When the 600- an d 800-mu g groups were compared, there were still significantly more women complaining of abdominal pain (P < .001). None of the women in the study re quired analgesics for pain or antipyretics for fever. Conclusion: The minimal evacuation interval should be at least 3 hours for successful preabortion cervical priming. (C) 1999 by The American College o f Obstetricians and Gynecologists.