Misoprostol monotherapy versus adjunctive mechanical cervical ripening with Foley catheter or Dilapan-S for second-trimester termination of pregnancy: A randomized controlled trial
Neda Torabifar, Fatemeh Yousefi, Shahla Faal Siahkal, Sara Kord, Salimeh MoradinasabBACKGROUND:
In regions where mifepristone access is legally or logistically constrained, second-trimester pregnancy termination predominantly relies on misoprostol-only regimens. However, these protocols are often associated with a prolonged induction-to-abortion interval (IAI). This study evaluated whether integrating mechanical cervical ripening agents—specifically Foley catheters or Dilapan-S rods—could enhance the clinical efficiency of misoprostol-induced terminations in mifepristone-restricted settings.
MATERIALS AND METHODS:
In this single-center, open-label randomized controlled trial (February–October 2023), 90 women with singleton pregnancies between 13 + 0 and 20 + 6 weeks’ gestation were randomly assigned (1:1:1 ratio) to one of three groups: (1) vaginal misoprostol monotherapy (400 µg every 3 h); (2) misoprostol plus a 24F Foley catheter (balloon inflated to 40 mL); or (3) misoprostol following a 4-h cervical preparation with a Dilapan-S osmotic dilator. Sample size was calculated to detect a 30% reduction in median IAI (α = 0.05, β = 0.20), requiring 75 participants; 90 were enrolled to account for 20% attrition. Randomization employed computer-generated blocks with allocation concealment via SNOSE (sequentially numbered, opaque, sealed envelopes). Primary outcomes were IAI and total procedure time. Secondary outcomes included 24-h success rate, cumulative misoprostol dose, adverse events, and patient-reported acceptability. Statistical analyses used Kruskal–Wallis, Chi-square, and Kaplan–Meier log-rank tests, with significance defined as
RESULTS:
Median IAI did not differ significantly among groups (misoprostol: 600 min, Foley: 714 min, Dilapan-S: 698 min;
CONCLUSION:
Adjunctive use of Foley catheters or Dilapan-S does not accelerate the induction-to-abortion process in second-trimester terminations compared with misoprostol monotherapy in mifepristone-restricted settings. Given the significantly longer total procedure time of Dilapan-S and its 15-fold higher cost without clinical benefit, vaginal misoprostol monotherapy remains the most pragmatic and cost-effective strategy. Larger multicenter trials are warranted to detect potentially subtle differences in clinical efficacy.
TRIAL REGISTRATION:
Iranian Registry of Clinical Trials (IRCT20210516051312N2).