Sacral neuromodulation for faecal incontinence following obstetric sphincter injury - outcome of percutaneous nerve evaluation.

Aim The purpose of this study was to assess the efficacy of percutaneous nerve evaluation (PNE) in women with faecal incontinence (FI) following obstetric anal sphincter injury and relate the outcomes to baseline factors with special emphasis on the extent of sphincter defect. Method This was a prospective study at a tertiary colorectal referral unit at the University Hospital of North Norway conducted from 2012-2014. Sixty-three women underwent a three–week PNE using a tined lead and the Verify® external neurostimulator. The primary outcome was efficacy defined as the percent of reduction in weekly FI episodes, and patients with 50% or more reduction were defined as responders. Baseline factors affecting the primary outcome were explored. Sphincter defects were classified with a validated 3D endoanal ultrasound defect score. Results Fifty-six (89%) of the 63 women were responders with a reduction in weekly FI episodes of 94.5%, from median (interquartile range) 4.8 (2.0-11.0) to 0.5 (0-2.0, p<0.001). Twenty-nine (52%) reported no weekly FI episodes, and urgency episodes disappeared in 18 (32%). In the multivariable linear regression model, efficacy was related to concomitant urinary incontinence (p=0.04), body mass index (BMI) (p=0.03) and pain during PNE (p=0.046) but not to the extent of sphincter defect (p= 0.1). Responders had a higher St. Mark's score than non-responders (p=0.046). Conclusions The vast majority of women had successful PNE tests. Responders had higher baseline St. Mark's scores than non-responders. Efficacy was related to concomitant urinary incontinence, BMI and pain, not to the extent of sphincter defect. This article is protected by copyright. All rights reserved.