Mifepristone followed by misoprostol or oxytocin for second-trimester abortion: a randomized controlled trial

Abstract

Objective: To compare two methods for induction of second-trimester abortion after priming the cervix with mifepristone.

Methods: This was a randomized prospective trial carried out between January 2009 and February 2012. The participants were healthy women between 14 and 24 weeks of gestation with missed miscarriage or need for termination of pregnancy. All participants received oral 200 mg mifepristone and, after 36 hours, after randomization, were given either a high-concentration oxytocin drip (maximal dose of 150 milli-international units/min) for up to 36 hours or 800 micrograms misoprostol vaginally followed by 400 micrograms oral misoprostol every 3 hours with a maximum of four oral doses. If expulsion of the fetus was not achieved, another 200 mg mifepristone was administered and another course of misoprostol was delivered as described previously. The primary outcome measure was success expulsion of the fetus in 36 hours since starting on uterotonic agent. Secondary outcomes included time until expulsion of the fetus and rate of adverse outcomes.

Results: Success rates in the mifepristone-misoprostol and mifepristone-oxytocin arms were 100% (70/70 patients) and 95.8% (69/72), respectively (relative risk 1.043, 95% confidence interval 0.99-1.10, P=.13). Time until fetal expulsion was shorter in the mifepristone-misoprostol arm (7.0 ± 4.9 hours compared with 11.3 ± 7.4 hours, P<.001). However, the rate of adverse effects in the misoprostol group was higher than in the oxytocin group. Factors associated with a shorter time until expulsion were missed miscarriage compared with therapeutic abortion, increased ultrasonographic gestational age, and increased parity.

Conclusion: The two regimens studied had comparable efficacy for induction of second-trimester abortion; however, the mifepristone-oxytocin regimen has a longer time until expulsion but with fewer side effects.

Clinical trial registration: ClinicalTrials.gov, www.clinicaltrials.gov, NCT00784797.

Level of evidence: : I.