BACKGROUND: The United States Food and Drug Administration (FDA) has approved the use of mifepristone (RU 486) in a protocol for early medical abortion.1 In that protocol, 600 μg of mifepristone is followed by 400 μg of oral misoprostol 48 hours later. Previous studies have shown that low-dose mifepristone (200 μg) followed 2 days later by 800 μg vaginal misoprostol has fewer side effects and is more effective than the approved protocol. Restricting administration of vaginal misoprostol to a narrow time window 2 days after the mifepristone dose may be inconvenient or unsafe.
POPULATION STUDIED: Healthy pregnant women aged 18 years and older who desired abortions were recruited from 16 sites including hospitals, abortion clinics, family practice offices, and gynecology offices. A total of 2295 women were recruited, and all underwent a transvaginal ultrasound to rule out ectopic pregnancy and to confirm fetal size consistent with a gestation of 56 days or less.
STUDY DESIGN AND VALIDITY: This is an unblinded randomized controlled trial with 3 arms. Subjects were assigned by concealed computer-generated randomization to self-administered 800 μg misoprostol vaginally either 1 (n=745), 2 (n=778), or 3 (n=772) days after a 200-μg dose of mifepristone.
OUTCOMES MEASURED: Complete medical abortion without surgical intervention was the primary outcome.
RESULTS: There was no statistically significant difference in the percentage of women who had complete medical abortions across the 3 groups. The percentages of complete medical abortions for the day 1 and day 2 groups were both 98% (95% confidence interval [CI], 97%-99%), and for the day 3 group it was 96% (95% CI, 95%-97%).
Low-dose mifepristone (200 μg) followed 1 to 3 days later by 800 μg of self-administered vaginal misoprostol is a safe and effective procedure for early medical abortion. Rigid adherence to the oral administration of misoprostol in a medical office 48 hours after mifepristone is not necessary either from a safety or efficacy perspective. Administration of misoprostol 1 or 2 days after mifepristone is preferable, since patients in the day 3 group found the wait less acceptable. Information is available on the Internet about FDA special requirements and approved protocols involving mifepristone.1