The use of misoprostol for pre-operative cervical dilatation prior to vacuum aspiration: a randomized trial

Misoprostol is effective for cervical priming prior to vacuum aspiration for first trimester termination of pregnancy. Previous studies showed that the oral route was more acceptable to patients but there were higher incidences of side-effects when compared with the vaginal route. This study is to determine the optimal dosage and route of administration of misoprostol for pre-operative cervical dilatation. A double-blind, randomized trial was undertaken for 225 nulliparous women with 8-12 weeks amenorrhoea. They were randomly assigned to groups given 0 (placebo), 200 or 400 microg oral or vaginal misoprostol 3 h prior to vacuum aspiration. In misoprostol-treated groups the baseline cervical dilatation was significantly increased when compared with the placebo group; the effect was dose-related in the oral but not in the vaginal group. The cumulative force and blood loss was significantly decreased in the misoprostol-treated groups. The incidences of side-effects were more frequent in misoprostol groups but were not related to the route and dosage of medication. The duration of procedure, incidences of post-operative complications, the duration of post-operative bleeding and the interval to the first period were similar in the five treatment groups. We conclude that a 3 h pre-treatment interval is effective for both oral and vaginal routes. When given orally, 400 microg is more effective than 200 microg. The efficacy was otherwise similar when compared with the vaginal route. We recommend 400 microg oral misoprostol 3 h prior to vacuum aspiration for cervical dilatation.