Recovery of the internal anal sphincter and continence after restorative proctocolectomy

Abstract

The internal anal sphincter (IAS) was assessed prospectively using electromyography and manometry in 66 patients (48 men) undergoing restorative proctocolectomy to determine its role in the gradual return of continence. Twenty-nine patients received a J pouch and 37 a W reservoir. Some 38 pouches (J, ten; W, 28) were hand-sewn (mucosal proctectomy with endoanal anastomosis) and 28 (J, 19; W, nine) stapled (end-to-end pouch-anal anastomosis 1 cm above the dentate line). Twelve patients underwent a one-stage procedure (all J pouches), while the remainder had a covering loop ileostomy. Each patient was reassessed immediately after restorative proctocolectomy and again at 7 days, 1 month, 4 months, 9 months and 18 months after pouch formation. Internal sphincter electromyographic activity was greatly reduced after pouch-anal anastomosis (median preoperative frequency 0.51 Hz versus immediate postoperative frequency 0.21 Hz, P < 0.003) and gradually recovered from 4 months after surgery. At 18 months, measurements of IAS function had not fully recovered to preoperative values (median frequency 0.31 Hz; P < 0.03). Resting anal pressures (median preoperative value 99 cmH2O) decreased by over 50 per cent after surgery (median immediate postoperative resting pressure 44 cmH2O) and recovered gradually but incompletely (median pressure at 18 months 63 cmH2O). Eleven patients reported leakage in the follow-up period. The median (range) resting pressure in these patients (54 (40-71) cmH2O) was not significantly different at 9 months from that of those who were continent either before or after operation (59 (46-68) cmH2O). Prolonged recordings in patients with faecal leakage revealed evidence of high-pressure pouch waves that overwhelmed anal sphincter pressures and coincided with leakage. These episodes were most common during sleep, when anal sphincter activity was reduced.