Risk factors and outcome of repair of obstetric anal sphincter injuries as followed up in a dedicated perineal clinic.

INTRODUCTION AND HYPOTHESIS: Faecal incontinence can be a devastating outcome with social, psychological and physical repercussions, and it occurs in 10-61% following obstetric anal sphincter injury (OASIS). The aim of our study was to determine the contributing factors in the development of severity of OASIS and to correlate anal sphincter tone with the extent of anal sphincter injury. METHODS: A prospective cohort study was performed of all patients attending the postnatal perineal clinic at 4-12 months postpartum, from January 2016 until October 2017. Women were categorised into minor tears (3a and 3b) and major tears (3c and 4th degree). RESULTS: The mean age was 33.9 years (4.2); the mean parity was 1.6 (range 1-5). A total of 75 women (17%) were reviewed following a major tear (4th degree, n = 28, 3c, n = 47) and 362 (83%) were reviewed following a minor tear (3a n = 188, 3b, n = 174). Following analysis of numerous obstetric variables, it was shown that women who had an instrumental delivery were more likely to have a major tear compared with those who had a spontaneous vaginal delivery (p = 0.05). A significant difference was found in the distributions of symptom score between groups (p < 0.001). Women with combined defects were most likely to have reduced anal tone (p < 0.001) compared with any other group. CONCLUSIONS: The perineal clinic provides a valuable resource for investigation and treatment of OASIS, providing a targeted pathway for management. We suggest that endoanal ultrasound and digital rectal examination are complimentary investigations which correlate well with each other.