Predictors of Success With Sacral Nerve Stimulation for Faecal Incontinence—Results From a Single Centre Over 15 Years

BACKGROUND: Sacral nerve stimulation (SNS) is an accepted first-line surgical treatment for faecal incontinence (FI) with variable success. This study aims to analyse the parameters that may predict initial and sustained success with SNS in patients with FI. METHODS: A retrospective audit was conducted on 56 patients with FI managed with SNS implantation by a single Australian colorectal surgeon. A successful outcome was defined as a 50% or greater reduction in the number of FI episodes per week at the end of the two-week trial period (temporary stimulation) or at their last follow-up visit (permanent implantation). Patient characteristics, pre-implantation anal manometry, endoanal ultrasound and electrophysiological testing were compared on univariate analysis between success and failure groups. RESULTS: Temporary stimulation was successful in 53.6% of patients. Thirty patients proceeded to permanent SNS with 21 (70%) patients having ongoing success over a median follow-up of 50.2 months. BMI > 25 and reduced maximal tolerable volume on pre-implantation anal manometry studies predicted success of temporary SNS (p = 0.013 and p = 0.02, respectively). Whereas a history of vaginal or bladder prolapse surgery predicted failure of temporary SNS (p = 0.012). CONCLUSION: This study identified baseline BMI > 25 and relative hypersensitivity of rectal distension predicted success of temporary SNS. A history of previous surgery for vaginal or bladder prolapse was associated with failure. We failed to identify any clinical or pre-assessment parameter that predicted long-term success with permanent stimulation.