Cervical Dilators Used Concurrently With Misoprostol to Shorten Labor in Second-Trimester Termination of Pregnancy: A Randomized Controlled Trial

Objective: To evaluate the use of cervical dilators concurrently with misoprostol to shorten labor in second-trimester medical termination of pregnancy.

Methods: This multicenter randomized controlled trial compared the efficacy of cervical dilators inserted concurrently with misoprostol with that of misoprostol, alone, to shorten labor for women undergoing termination of pregnancy between 15 0/7 and 27 6/7 weeks of gestation. The primary outcome was the proportion of women with a duration of labor exceeding 12 hours. Secondary outcomes included median duration of labor, time to amniotomy, side effects, complications, NPRS (Numeric Pain Rating Scale) score, and women's distress as measured by the IES-R (Impact of Event Scale-Revised). These outcomes also were studied separately in the nulliparous subgroup. To demonstrate a reduction of 50% of the proportion of women with a duration of labor exceeding 12 hours in the dilator group, with a power of 80% and a 2-sided 0.05 significance level, a sample of 268 women (134 in each group) was required.

Results: Between December 2017 and September 2019, this study enrolled and analyzed 347 women: 174 in the dilator group and 173 in the control group, including 87 and 93 nulliparous patients, respectively. Sociodemographic and obstetric characteristics were similar between groups. The proportion of women with labor exceeding 12 hours was not different between groups (49/174 [28.2%] in the dilator group vs 53/173 [30.6%] in the control group [ P =.61] for the whole population, and 37/87 [42.5%] vs 42/93 [45.2%] [ P =.72], respectively, among nulliparous patients). Median duration of labor was 8.5 hours in the dilator group compared with 9.2 hours in the control group ( P =.65) for the whole population, and 10.5 hours compared with 11.8 hours, respectively, among nulliparous patients ( P =.33). Median time to amniotomy was 3.6 hours in the dilator group compared with 5.0 hours in the control group ( P =.08) for the whole population, and 3.5 hours compared with 6.7 hours, respectively, among nulliparous patients ( P =.003). Side effects, complications, NPRS score, and IES-R score were similar between groups.

Conclusion: Cervical dilators inserted concurrently with misoprostol did not reduce the proportion of women whose labor exceeded 12 hours compared with misoprostol alone.

Clinical trial registration: ClinicalTrials.gov , NCT03194230.