Background: The recommended time interval between mifepristone and misoprostol in medical second trimester termination of pregnancy (TOP) has been 36-48 h. However, a more flexible interval would be of value. The aim of this investigation was to compare one- and two-day intervals in second trimester medical TOP. The main outcome measures were induction-to-abortion time and the rate of surgical evacuation.
Methods: This open randomized trial included 227 women undergoing TOP between gestational weeks 13-24. Mifepristone (200 mg) was followed by misoprostol (400 mcg) after one (17-28 h) or two (41- 45 h) days.
Results: In intention-to-treat analysis, the median induction-to-abortion interval was 1h longer in the one-day group (8.5 versus 7.2 h, P = 0.038), but in per-protocol analysis, the rate of surgical evacuation was higher in the 2-day group [30/115 (25%) versus 40/112 (37%); 95% confidence interval 0.3-24.1, P = 0.044]. A subgroup analysis showed that the median induction-to-abortion interval was 3h longer in the one-day group, amongst women without previous vaginal deliveries (10.1 versus 7.6, P = 0.013) and when gestation exceeded 16 weeks (10.8 versus 7.2, P = 0.024).
Conclusions: Both one- and two-day dosing intervals seem to be suitable for second trimester medical TOP, but women with no previous deliveries and those whose gestation exceeds 16 weeks may benefit from the longer interval. However, evaluated on the basis of surgical evacuation, the one-day interval could be supported as an option for second trimester medical TOP. Effective use of both one- and two-day dosing intervals is important when optimizing clinical service.
Trial registration: ISRCTN09944151.