Posterior Tibial Nerve Stimulation for the Treatment of Fecal Incontinence Following Obstetric Anal Sphincter Injury

Objectives Obstetric anal sphincter injuries (OASI) are a major risk factor for fecal incontinence (FI). Neuromodulation is often used as second‐line therapy for FI, but evidence for its efficacy is conflicting. We aimed to evaluate the efficacy and predictive factors of posterior tibial nerve stimulation for obstetric anal sphincter injury‐induced FI. Materials and Methods Consecutive females with FI related to past OASI who had not responded to first‐line therapy and had received 8–12 weeks of posterior tibial nerve stimulation were included. Subjects aged more than 50 and/or having other causes of FI were excluded. Patients underwent anorectal physiology and endoanal ultrasound pretherapy. Symptom burden was evaluated pretherapy and posttherapy using Rockwood and Wexner scales. A Wexner score reduced to below 10 or halved was used to define responders. Results A total of 37 females (mean age 38 years, median parity 2) were included. About 17 (46%) had ultrasonographically visualized anal sphincter defects and 41% had a history of third or second‐degree perineal tears. About 14 subjects (38%) were deemed responders. Compared with nonresponders, responders had lower baseline rectal distension thresholds and tended to have disrupted (59%) than intact sphincters (20%, p < 0.01). Responders demonstrated improvement in Rockwood score for depression and embarrassment, visual analogue score for bowel symptoms and stool consistency (median baseline Bristol score 5, to 3 posttherapy; p < 0.01). Conclusions Of a well‐defined cohort of females with FI secondary to OASI, 38% responded to posterior tibial nerve stimulation. Much of this improvement may relate to improvement in stool consistency.