Pre-pouch ileitis: a disease of the ileum in ulcerative colitis after restorative proctocolectomy

Ileal inflammation in ulcerative colitis can occur as backwash ileitis or prestomal ileitis. After restorative proctocolectomy (RPC), ileal inflammation may be present in the pouch (pouchitis) but inflammation proximal to the pouch in the neo-terminal ileum, so called pre-pouch ileitis (PI), has also been observed. As pouchitis is increasingly common and PI can mimic it, our aim was to characterize this condition.

A review of prospectively collected data on 571 inflammatory bowel disease patients undergoing follow-up after RPC in a single centre over 22 years was performed. The histology of biopsy material was reviewed and staining for colonic mucosal phenotypic changes was undertaken. It was not routine practice to prospectively assess all patients for pre-pouch ileitis when the database was constructed.

Of 19 patients with inflammation of the pre-pouch neo-terminal ileum (NTI) identified three had Crohn's disease and one a NSAID stricture. The remaining 15 had a characteristic diffuse inflammation extending from the NTI-pouch junction proximally: pre-pouch ileitis. The inflammation extended proximally for up to 50 cm. Fistula formation was seen in only one. Seven (47%) of 15 had pouchitis but only two had suffered backwash ileitis pre-operatively. Seven responded to medical therapy and four to surgery. The histological appearances including staining for colonic phenotypic change were similar in PI and pouchitis.

Pre-pouch ileitis is uncommon. As the patients' previous diagnosis of UC was confirmed and there was no radiological or histological evidence of Crohn's disease, PI appears to have a distinct pathogenesis from Crohn's disease.