Diversion-associated bowel diseases

Abbreviations

Introduction

Diversion colitis, proctitis, and pouchitis result from defunctionalized, surgically bypassed bowel segment. Diversion-associated bowel disease (DABD) occurs in fecal-stream bypassed segments of the bowel, following stoma surgery for congenital, inflammatory, or neoplastic disorders. The degree of inflammation of the bypassed segment of lower gastrointestinal track is largely determined by the extent of dependency of epithelia of the bowel on short-chain fatty acids (SCFAs), the fermented produces of gut luminal bacteria and dietary fibers. For example, the risk for diversion-associated mucosal injury of the ileum is different from that of the colon. Long-term fecal diversion often results in intrinsic luminal strictures in the bypassed bowel segment, with anastomosis, distal rectum, or anal canal carrying the highest risk. In addition, patients with a long history of inflammatory bowel disease (IBD) carry a risk for the development of colitis-associated neoplasia (CAN), and the diverted bowel is not an exception. The best treatment option for DABD is the closure of stoma and reestablishment of the natural route of defecation. However, closure of the stoma in patients is not possible or feasible, for personal and medical reasons. In addition, the excision of the diverted segment of bowel is often associated with complications, particularly persistent perineal sinus . Therefore some patients may have to have long-term or permanent fecal diversion, which pose the risk for various forms of diversion-associated disorders ( Table 13.1 ). Endoscopy plays a key role in the diagnosis, disease monitoring, surveillance, and treatment of diversion bowel disease.