Colo-Gastric Fistula as an Uncommon Complication of Crohn`s Disease: A Case Series

BACKGROUND: Colo-gastric fistulas are a rare complication of Crohn's disease with 10 year disease duration and known ileal disease or ileocolic anastamosis. Fistula most often form through spread of serosal inflammation from mid- to distal-transverse colon to the greater curvature of stomach due to anatomic proximity. Fistula are frequently noted on imaging done for increased IBD symptoms, however barium enema is the test of choice for diagnosis with 85-95% sensitivity. Here we detail two cases of colo-gastric fistula with unusual features. CASE 1: A 52-year-old male was referred to IBD clinic for evaluation after severe inflammation and pseudopolyps were noted on screening colonoscopy. He had history of perirectal abscess requiring surgical repair ten years previously and intermittent crampy abdominal pain with 4-5 loose stools daily for several years. CT enterography was notable for inflammation in both small bowel and colon including the terminal ileum. He was initially managed with short course prednisone and induction of ADA, with addition of AZT after return of symptoms off steroids. EGD was done for progressive symptoms notable for 10mm fistula along greater curvature of the stomach in communication with transverse colon. He underwent right hemicolectomy with primary repair of colo-gastric and incidental duodenopancreatic fistula noted at time of surgery. JP drain was placed in anticipation of biliary leak due to duodenopancreatic fistula; fluid amylase initially elevated but downtrended with appropriate drainage. He was continued on ADA and AZT post-operatively with remission achieved. CASE 2: A 53-year-old female with 30 year history of Crohn's Disease complicated by chronic perianal fistula presented with acute onset pain, nausea and vomiting. She had been off maintenance therapy for five years prior to starting ustekinumab four weeks prior to presentation. CT revealed fistula between mid-transverse colon and greater curvature of the stomach. She was started on IFX induction, prednisone, and AZT with referral to IBD clinic for further evaluation. EGD was notable for very small fistula tract. She underwent second IFX induction dose prior surgery with right hemicolectomy and primary fistula repair. She was continued on IFX and AZT post-operatively with remission achieved. DISCUSSION: Fistula should be addressed once discovered as colonic content exposure to the gastric mucosa can induce bacterial overgrowth and malabsorption. Management is primarily surgical although there have been cases of closure with use of 6-MP for colo-gastric fistula and IFX for duodenopancreatic fistula without surgical intervention. Most common surgical management is ileocolonic resection with primary fistula repair, although sometimes requires permanent diversion or staged repair. Long-term management involves control of IBD inflammation with both IFX and ADA showing significant benefit in fistulizing Crohn's with effects enhanced by AZT. Outcomes have only been studied up to six years post-operatively but are overall good without recurrence if underlying disease controlled.