Crohn's Disease of the Pouch: A True Diagnosis or an Oversubscribed Diagnosis of Exclusion?

Background: After IPAA, 8% of patients with ulcerative colitis are later diagnosed with Crohn's disease of the pouch, associated with an increased rate of pouch failure. No study has reported on how often the clinical diagnosis is correlated with histologic findings of Crohn's disease in the excised pouch. Objective: The purpose of this study was to determine whether the clinical diagnosis is consistent with pathologic confirmation at pouch excision. Settings: The study was conducted at a tertiary IBD referral center. Patients: Patients with chronic ulcerative colitis who underwent pouch excision for presumed Crohn's disease of the pouch were included. Main Outcome Measures: Preoperative evaluation and pathologic variables at the time of pouch excision were measured. Results: A total of 35 patients underwent pouch excision for Crohn's disease of the pouch based on a combination of clinical, radiographic, and endoscopic findings. Seven (20%) had surgical pathology consistent with Crohn's disease at pouch excision. There were no differences in those 7 patients and the remaining 28 in terms of diagnosis at colectomy, primary pouch symptoms, prepouch inflammation, ulceration, or granulomas at endoscopy. In the nonpathology-confirmed Crohn's disease, 40% (n = 11) had an anastomotic leak at time of IPAA versus 0% in the Crohn's disease group, and 86% (n = 24) had symptoms of pouch dysfunction within 5 months of ileostomy reversal versus 13 months in the Crohn's disease group. Of 28 without pathology-confirmed Crohn's disease, 100% (n = 28) were treated with antibiotics, 68% (n = 19) with steroids, 59% (n = 16) with immunomodulators, and 57% (n = 15) with biologic therapy for Crohn's disease of the pouch. Limitations: The study was limited by its single-center scope and lack of an established definition for Crohn's disease of the pouch. Conclusions: Pathologic confirmation of Crohn's disease was given to only one fifth of patients who underwent pouch excision for Crohn's disease of the pouch. Given the histologic variability in Crohn's disease, it may be unreasonable to expect histologic confirmation in every case; still, the diagnosis of Crohn's disease of the pouch may be overly ascribed, resulting in unnecessary immunosuppressive medications and exclusion from consideration for pouch reconstructive surgery.