Pouch adenomas in Familial Adenomatous Polyposis after restorative proctocolectomy

Australian Clinical Practice Guidelines suggest six to twelve-monthly endoscopic pouch surveillance in patients after restorative proctocolectomy for Familial Adenomatous Polyposis (FAP). There are several reports of adenomas and carcinomas forming within the ileum, ileal pouch mucosa or residual rectal mucosa. A retrospective clinical study was performed to audit pouch endoscopic surveillance at a large Sydney tertiary referral Hospital. The aim was to evaluate adenoma development after restorative proctocolectomy for FAP and the adherence rate to published clinical guidelines.

Thirty-nine patients who had restorative proctocolectomy for FAP from 1985 to 2011 were identified. Demographic data, details of surgery, original histopathology and details of follow-up pouch endoscopy and pathology findings were obtained.

Of the thirty-nine patients, twenty-seven patients were included in this study. Adenomas were found in twelve of 27 (44%) patients. Mean time to first polyp formation was 88 months and median time was 72 months (range 18-249 months). All polyps were either tubular or tubulovillous in histology. One polyp had high grade dysplasia. The remainder had mild or moderate dysplasia. Polyps were excised either endo-anally or during pouchoscopy. None of the five patients who had a hand-sewn ileal pouch-anal anastomosis (IPAA) developed polyps on follow-up, compared with 12 of the 22 (55%) with a double stapled anastomosis (fishers exact test; p=0.047 (two-tailed)). Of those who developed pouch adenomas, eight (67%) developed further pouch adenomas on follow-up.

This study supports guidelines recommending lifelong pouch surveillance after restorative proctocolectomy for FAP. Those who develop pouch adenomas may be at greater risk of developing further adenomas. Residual rectal mucosa at the pouch-anal anastomosis should be carefully examined.