Integrity of the anal sphincters after pouch-anal anastomosis: Evaluation with three-dimensional endoanal ultrasonography

PURPOSE: The aim of the present study was to assess the integrity of the anal sphincters after handsewn pouch-anal anastomosis performed with the help of a Scott retractor. For this purpose the anal sphincters were visualized with three-dimensional endoanal ultrasonography. METHODS: Patients undergoing a colonic pouch-anal anastomosis or an ileal pouch-anal anastomosis were included. Before and six months after the procedure, the length and volume of both sphincters were assessed with three-dimensional endoanal ultrasonography, and anal manometry was performed. Continence scores were determined using the Fecal Incontinence Severity Index (FISI). RESULTS: Fifteen patients with a colonic pouch and 13 patients with an ileal pouch were examined. Six months after the procedure, three-dimensional endoanal ultrasonography showed significant alterations of the internal anal sphincter in eight patients with a colonic pouch-anal anastomosis (53 percent) and in eight patients with an ileal pouch-anal anastomosis (62 percent). These alterations were characterized by asymmetry or thinning. No defects were seen in the colonic pouch group, but, in two patients with an ileal pouch, a small defect in the internal anal sphincter was found. A decrease in internal anal sphincter volume was seen only in patients with a colonic pouch-anal anastomosis (P = 0.009). In both groups the length of the internal anal sphincter and the length, thickness, and volume of the external anal sphincter remained the same. After the procedure a reduction of maximum anal resting pressure was found in both groups (colonic pouch: P < 0.001, ileal pouch: P = 0.001). Maximum anal squeeze pressure was reduced in only patients with an ileal pouch-anal anastomosis (P = 0.006). The observed alterations of the internal anal sphincter and the manometric findings showed no correlation with the postoperative Fecal Incontinence Severity Index scores. CONCLUSION: Handsewn pouch-anal anastomosis, performed with the help of a Scott retractor, only rarely leads to internal anal sphincter defects, but three-dimensional endoanal ultrasonography shows alterations of the internal anal sphincter in 57 percent of the patients. No correlation was observed between these alterations and the functional outcome.