Introduction: The Anal Transition Zone (ATZ) after stapled Ileal Pouch Anal Anastomosis (IPAA) for Ulcerative Colitis (UC) is considered at risk for dysplasia and persistent or recurrent disease activity, yet the long-term effects of the histologic ATZ changes on defecatory function are not well described.
Methods: We performed this prospective observational study to document the inflammatory and preneoplastic changes of the ATZ after stapled IPAA in a cohort of UC patients with no history of preoperative dysplasia. In our series, UC patients with biopsy proven preoperative dysplasia underwent a complete mucosectomy with handsewn IPAA. Study patients were scheduled to undergo yearly biopsy of the ATZ and were asked to record their functional status on a questionnaire/dairy for one week at 3, 6, 9, 12, 18, 24 months and yearly thereafter after the IPAA. Histologic changes were correlated with simultaneous assessment of defecatory function.
Results: Between 1992 and 2005, 169 consecutive UC patients (59% male, mean age 33.7 + 19.1 years; range 13-66 yrs) underwent a stapled IPAA (median follow-up 37.8 months, range 3-132). During the study period 223 successful biopsy of the ATZ were performed. There was no evidence of dysplasia in any of the biopsies performed. Nine biopsies showed evidence of acute inflammation (4%), 195 chronic inflammation (87.4%) and 19 (8.5%) were read as normal. In the chronic inflammation group, the average number of bowel movements was 6 + 1.9/day (range 2-10) versus 5 + 1.4/day (range 4-6) in patients with normal biopsies and 8 + 1.4/day (range 7-9) in patients with acute inflammation. Other indicators of stooling function, such as: consistency of bowel movements, dependence on anti-diarrheal medication, ability to always postpone a bowel movement did not differ between groups. In the chronic inflammation group, 94.7% of patients reported perfect continence, 88.6% were able to defer a bowel movement as needed and only 8.5% were using protective pads.
Conclusions: We conclude that preservation of the ATZ in UC patients with no history of preoperative dysplasia is safe and it is associated with excellent long-term functional results. The risk of acute inflammation and new onset dysplasia is minimal. Chronic inflammatory changes although very common, have limited clinical impact on defecatory function.