Is there an association between bariatric surgery and Crohn's disease?

Bariatric surgery is an established treatment for selected obese patients resulting in significant long-term weight reduction. The association of morbid obesity, bariatric surgery and Crohn's disease is not well understood. Up to date, only few cases have been described in the English literature. The aim of this study was to determine the frequency of new onset Crohn's disease in patients after bariatric surgery. In a retrospective chart review all patients undergoing bariatric bypass surgery in a defined time period were evaluated. We report clinical and endoscopic findings of these patients, together with histopathological characterization of biopsies from the lower GI tract. From January 2009 to October 2016, 490 gastric bypass procedures were performed in our institution. During regulary clinical follow-up, 21 patients (4.3%) underwent colonoscopy because of unexplained chronic diarrhoea (8/21 pts.), abdominal pain (11/21 pts.), abdominal bloating (5/21 pts.) or anemia (6/21 pts.). In 27.3% (6/21 pts. – age range 19 – 46, BMI from 32 to 40 m2/kg), endoscopy revealed small ulcerations in the terminal ileum suspicious of Crohn's disease. All patients had elevated calprotectin levels. Histology confirmed clinical findings: focal chronic active enteritis (terminal ileitis) with aphthous ulceration was seen in all biopsy specimens. Subsequently all patients were diagnosed with Crohn's disease. 5/6 pts. received therapy and were eventually free of symptom. Our study shows a potential association between bariatric surgery and development of postoperative Crohn's disease. We speculate that the anatomic changes caused by bariatric surgery trigger alteration of the intestinal microbiome in predisposed patients. This may result in chronic inflammation of the bowel mucosa causing changes seen in Crohn's disease. Our findings should increase the awareness of the clinicians regarding patients undergoing bariatric surgery and the possibility of developing Crohn's disease with subsequent impact on clinical management, such as follow-up and surveillance strategies.

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