Pre-operative cervical preparation before first trimester vacuum aspiration: a randomized controlled comparison between gemeprost and mifepristone (RU 486).

OBJECTIVE--To compare the effectiveness of 200 mg mifepristone with 1 mg gemeprost vaginal pessary in achieving cervical dilatation and softening ('priming') before late first trimester pregnancy vacuum aspiration. DESIGN--A randomized, operator blind, placebo controlled trial. SETTING--UK teaching hospital. SUBJECTS--90 primigravid women with 63-91 days amenorrhoea and ultrasonically confirmed single living fetus of correct size for gestational age. INTERVENTIONS--The women were allocated to receive 200 mg mifepristone orally or an identical oral placebo 36 h before operation or 1 mg gemeprost vaginal pessary 3-4 h preoperatively. MAIN OUTCOME MEASURES--Onset of new symptoms following drug administration, a proven objective measure of the force required to dilate the cervix, and estimated intraoperative blood loss. RESULTS--There were no significant differences in the baseline cervical dilatation, the force required to dilate the cervix or the volume of intraoperative blood loss between the active treatment groups. Both drugs were significantly more effective than placebo. Significantly fewer women in the mifepristone group had adverse side effects than in the gemeprost group. CONCLUSIONS--Mifepristone is a highly effective cervical priming agent, and has the advantages of being an oral preparation associated with few side effects.