Crohn’s Disease of the Ileoanal Pouch: A High Rate of Potential Overdiagnoses

Abstract

Abstract Background Approximately 1 in 10 patients with an ileal pouch–anal anastomosis is diagnosed with Crohn’s disease of the pouch (CDP). However, this diagnosis may be established inappropriately, as alternative underlying causes necessitating an alternative treatment approach, such as long-term surgical sequelae, may mimic CDP. In this study, we aimed to identify patients diagnosed with and treated for CDP with a (concurrent) alternative diagnosis. Methods Ulcerative colitis and inflammatory bowel disease unclassified patients who underwent ileal pouch–anal anastomosis surgery in a tertiary center between 1990 and 2017 were retrospectively reviewed. Patients with a postoperative diagnosis of CDP for which medical treatment was initiated were identified. Presence of pouchitis, prepouch ileitis, stricture, and fistulas was assessed and histopathological reports were evaluated. Thereafter, cross-sectional images of the pouch in CDP patients were re-evaluated to identify potential long-term surgical sequelae (ie, chronic presacral sinus or perianastomotic fistulas). Results After a median postoperative follow-up of 6.2 (interquartile range, 2.3-13.5) years, 47 (10%) of 481 patients were diagnosed with CDP. CDP patients had pouchitis (n = 38 [81%]), prepouch ileitis (n = 34 [74%]), strictures (n = 17 [36%]), fistulas (n = 15 [32%]), or a combination. Multiple granulomas were found in 1 pouch resection specimen. Re-evaluation of 40 (85%) patients who underwent magnetic resonance imaging revealed presence of long-term surgical sequelae in 17 (43%) patients. Six (15%) patients demonstrated isolated nonanastomotic fistulas. Conclusion Re-evaluation of cross-sectional imaging of the pouch revealed that potential alternative causes were found in nearly half of CDP patients. Cross-sectional imaging is therefore recommended early in the diagnostic pathway to exclude an alternative diagnosis.