Effect of an Intrapartum Pelvic Dilator Device on Levator Ani Muscle Avulsion During Primiparous Vaginal Delivery: A Pilot Randomized Controlled Trial

Introduction and Hypothesis: The objective was to evaluate the safety and effectiveness of an intrapartum electromechanical pelvic floor dilator designed to reduce the risk of levator ani muscle (LAM) avulsion during vaginal delivery. Methods: A multicenter, randomized controlled trial enrolled nulliparous participants planning vaginal delivery. During the first stage of labor, participants were randomized to receive the intravaginal device or standard-of-care labor management. The primary effectiveness endpoint was the presence of full LAM avulsion on transperineal pelvic-floor ultrasound at 3 months. Three urogynecologists performed blinded interpretation of ultrasound images. The primary safety endpoint was adverse events (AEs) through 3 months. Results: A total of 214 women were randomized to Device (n = 113) or Control (n = 101) arms. Of 113 Device assignees, 82 had a device placed, of whom 68 delivered vaginally. Of 101 Control participants, 85 delivered vaginally. At 3 months, 110 participants, 46 Device subjects who received full device treatment, and 64 Controls underwent ultrasound for the per-protocol analysis. No full LAM avulsions (0.0%) occurred in the Device group versus 7 out of 64 (10.9%) in the Control group (p = 0.040; two-tailed Fisher’s test). A single maternal serious AE (laceration) was device related; no neonate serious AEs were device related. Conclusions: The pelvic floor dilator device significantly reduced the incidence of complete LAM avulsion in nulliparous individuals undergoing first vaginal childbirth. The dilator demonstrated an acceptable safety profile and was well received by recipients. Use of the intrapartum electromechanical pelvic floor dilator in laboring nulliparous individuals may reduce the rate of LAM avulsion, an injury associated with serious sequelae including pelvic organ prolapse.