Follow up of women after Obstetric Anal Sphincter Injuries (OASI)- what is the role of anorectal studies? An observational study.

Abstract

Objective To evaluate the benefit of performing anorectal studies on all women following primary Obstetric Anal Sphincter Injury (OASI) repair over performing them on symptomatic women only. Design Retrospective observational study. Setting Tertiary maternity unit in the U.K. Population or sample All women followed up in the perineal clinic over 13 years were included. Methods Women who attended perineal clinic between 2007 and 2020 underwent symptom assessment and anorectal studies at 6 weeks and 6 months post-partum. Anorectal studies including endo anal ultrasound (EAUS) and anal manometry (AM) were performed. The anorectal studies of symptomatic women who were the case group, were compared with asymptomatic women who were the control group. Main outcome Results 1,348 women were seen in the perineal clinic over 13 years. 454 (33.7%) women were symptomatic. 894 (66.3%) women were asymptomatic. 313 (35%) asymptomatic women had two abnormal anorectal studies, 274 (31%) had abnormal AM alone and 86 (9.6%) had abnormal EAUS alone. 221 (24.7%) asymptomatic women had normal anorectal studies. Conclusion Almost 70% of women were asymptomatic 6 months following primary OASI repair. Most had at least one abnormal anorectal study result. Selectively performing anorectal tests on symptomatic women would not identify asymptomatic women at risk of future faecal incontinence (FI) following further vaginal birth. Without anorectal study results, women would not receive accurate counselling about the risks of vaginal birth. Anorectal studies should be offered to all women following OASI where resources allow.