Procedural outcomes comparing transcervical balloon with osmotic dilators prior to procedural abortion: a non-inferiority randomized trial

Objectives We aimed to compare the transcervical balloon and osmotic dilators for cervical preparation in second-trimester procedural abortions. Methods We performed an unblinded, randomized, non-inferiority trial of people undergoing a second-trimester abortion by dilation and evacuation between 18+0 and 23+6 weeks’ gestation. We randomized participants to receive either osmotic dilators or a balloon for overnight cervical preparation. All participants received mifepristone and misoprostol. All procedures were performed under deep sedation. We powered the study on the primary outcome of mean difference in procedure duration; the non-inferiority limit was defined as five minutes. Secondary outcomes included post-dilator cervical dilation, need for mechanical dilation, physician satisfaction, and ease of procedure. Results We recruited 32 participants over 13 months at a single academic center. Although transcervical balloon was similar to osmotic dilators in procedure time (22.6+8.9 minutes vs. 22.4+12.8 minutes), non-inferiority was not met (mean difference, 0.2 minutes; 95% confidence interval [CI], -7.8 to 8.2). Adequate cervical dilation (>2cm) was more likely achieved with osmotic dilators (100% vs. 62.5%, p=0.02). Additional mechanical dilation was less frequently needed with osmotic dilators (0% vs. 66.7%, p<0.001). Complications were minor and did not differ between the two groups (p=0.60). Conclusions While significantly more people with a balloon required mechanical dilation, the difference in operative time was clinically negligible. The transcervical balloon may be a safe alternative to osmotic dilators for cervical preparation for second-trimester procedures that is more affordable and accessible. We aimed to compare the transcervical balloon and osmotic dilators for cervical preparation in second-trimester procedural abortions. We performed an unblinded, randomized, non-inferiority trial of people undergoing a second-trimester abortion by dilation and evacuation between 18+0 and 23+6 weeks’ gestation. We randomized participants to receive either osmotic dilators or a balloon for overnight cervical preparation. All participants received mifepristone and misoprostol. All procedures were performed under deep sedation. We powered the study on the primary outcome of mean difference in procedure duration; the non-inferiority limit was defined as five minutes. Secondary outcomes included post-dilator cervical dilation, need for mechanical dilation, physician satisfaction, and ease of procedure. We recruited 32 participants over 13 months at a single academic center. Although transcervical balloon was similar to osmotic dilators in procedure time (22.6+8.9 minutes vs. 22.4+12.8 minutes), non-inferiority was not met (mean difference, 0.2 minutes; 95% confidence interval [CI], -7.8 to 8.2). Adequate cervical dilation (>2cm) was more likely achieved with osmotic dilators (100% vs. 62.5%, p=0.02). Additional mechanical dilation was less frequently needed with osmotic dilators (0% vs. 66.7%, p<0.001). Complications were minor and did not differ between the two groups (p=0.60). While significantly more people with a balloon required mechanical dilation, the difference in operative time was clinically negligible. The transcervical balloon may be a safe alternative to osmotic dilators for cervical preparation for second-trimester procedures that is more affordable and accessible.