Can Enteric Fistulae in Patients with Crohn's Disease Occur in Isolation: Findings from 500 Consecutive Operative Cases.

BACKGROUND OR PURPOSE: Enteric Crohn's disease (CD) is characterized by transmural inflammation resulting in inflammatory, stricturing, or penetrating phenotypes. However, data regarding the relationship between stricturing and penetrating behavior is lacking. The incidence of penetrating CD in the absence of a stricture is unclear. The aim of this study is to assess if enteric fistulae in adult patients undergoing abdominal surgery for symptomatic CD occur in isolation. METHODS: Resection or repair of enteric CD fistulae performed in a quaternary care referral center (2009-2017) was analyzed. Fistulae associated with pelvic or continent pouch, rectal stump, or ano-vagina were excluded. Fistulae were stratified based on origin, tract, target, and relationship to stricture. Strictures were stratified as inflammatory or fibrostenotic. RESULTS: Five hundred consecutive operative reports were reviewed. A total of 490 fistulae were evaluated. Two hundred ninety-nine fistulae were in patients undergoing index surgery. Incidence of CD fistulae not associated with stricture was 14.9% in total, but only 8% in the index surgery cohort. The majority of fistulae originated from the ileum (95%). CD fistulae originating from the stomach or duodenum were not identified in the index cohort. Fistulae within an inflammatory stricture were likely to include an intra-abdominal abscess (p < 0.001). Fistulae associated with a fibrostenotic stricture were more likely to originate proximal to the stricture (p < 0.001). The incidence of fistula-associated adenocarcinoma was 0.6%. CONCLUSIONS: Symptomatic CD fistulae in the absence of stricture are uncommon. Caution should be exercised when making a diagnosis of CD in the presence of enteric fistulae, but an absence of stricture, particularly in patients with prior abdominal surgery.