Preservation of the anal transition zone in ulcerative colitis. Long-term effects on defecatory function.

Introduction: The anal transition zone (ATZ) after ileal pouch anal anastomosis (IPAA) for ulcerative colitis is considered at risk for dysplasia and persistent or recurrent disease activity. The long-term fate of the ATZ and the effects of histologic changes on defecatory function are not well-known.

Methods: To evaluate the inflammatory and preneoplastic changes of the ATZ in patients without preoperative dysplasia, yearly biopsies of the ATZ were obtained and functional results recorded on a questionnaire/diary. Histologic changes were correlated with simultaneous assessment of defecatory function.

Results: Between 1992 and 2006, 225 patients underwent a stapled IPAA. A total of 238 successful biopsies of the ATZ were performed. There was no dysplasia found. Acute inflammation was noted in 4.6%, chronic inflammation in 84.9%, and normal mucosa in 10.5% of cases. Patients with chronic inflammation reported an average of 6.2+/-1.7 bowel movements/day and 93.2% of them were able to delay a bowel movement for at least 30 min. The presence of chronic ATZ inflammation did not seem to have a negative impact on function, with 96.1% of patients reporting perfect continence, and only 5.3% using protective pads.

Conclusions: Preservation of the ATZ in selected patients is safe and offers excellent long-term functional results. New onset dysplasia was not noted. Chronic inflammation had limited clinical impact. Presence of ATZ inflammation in a total of 89.5% of patients warrants life-long surveillance with biopsies.