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

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.

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.

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.

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.