Does the Epi-No® birth trainer prevent vaginal birth-related pelvic floor trauma? : a multicentre prospective randomised controlled trial

Objective Vaginal childbirth may result in levator ani injury secondary to overdistension during the second stage of labour. Other injuries include perineal and anal sphincter tears. Antepartum use of a birth trainer may prevent such injuries by altering the biomechanical properties of the pelvic floor. This study evaluates the effects of Epi-No ® use on intrapartum pelvic floor trauma. Design Multicentre prospective randomised controlled trial. Setting Two tertiary obstetric units in Australia. Population Nulliparous women carrying an uncomplicated singleton term pregnancy. Methods Participants were assessed clinically and with 4D translabial ultrasound in the late third trimester, and again at 3-6 months postpartum. Women randomised to the intervention group were asked to use the Epi-No ® device from 37 weeks of gestation until delivery. Main outcome measures Levator ani, anal sphincter, and perineal trauma diagnosed clinically and/or with translabial ultrasound imaging. Results Of 660 women randomised, 504 (76.4%) returned for assessment at a mean of 5 months postpartum. There was no significant difference in the incidence of levator avulsion [12 versus 15%; relative risk (RR) 0.82, 95% confidence interval (95% CI) 0.51-1.32; absolute risk reduction (ARR) 0.03, 95% CI -0.04 to 0.09; P = 0.39], irreversible hiatal overdistension (13 versus 15%; RR 0.86, 95% CI 0.52-1.42; ARR 0.02, 95% CI -0.05 to 0.09; P = 0.51), clinical anal sphincter trauma (7 versus 6%; RR 1.12, 95% CI 0.49-2.60; ARR -0.01, 95% CI -0.05 to 0.06; P = 0.77), and perineal tears (51 versus 53%; RR 0.96, 95% CI 0.78-1.17; ARR 0.02, 95% CI -0.08 to 0.13; P = 0.65). A marginally higher rate of significant defects of the external anal sphincter on ultrasound was observed in the intervention group (21 versus 14%; RR 1.44, 95% CI 0.97-2.20; ARR -0.06, 95% CI -0.13 to 0.05; P = 0.07). Conclusion Antenatal use of the Epi-No ® device is unlikely to be clinically beneficial in the prevention of intrapartum levator ani damage, or anal sphincter and perineal trauma. Tweetable abstract No evidence of a protective effect of the Epi-No ® device on intrapartum pelvic floor rauma.