Pathogenesis of Crohn’s Disease- and Ulcerative Colitis-Related Strictures

List of Abbreviations

Introduction

Stricture formation is a significant complication of inflammatory bowel disease (IBD) often requiring endoscopic or surgical intervention. Up to 30% of Crohn's disease (CD) patients and 5% of ulcerative colitis (UC) patients develop stricturing disease. Strictures are thought to be formed through a combination of inflammatory and fibrotic processes. Although strictures can arise anywhere in the gastrointestinal tract, the most commonly affected locations are the terminal ileum and ileocecal valve because of the fact that the majority of strictures are found in CD patients. Although less common, colonic strictures in UC are typically asymptomatic, benign, and related to degree of inflammation and fibrosis; however, given their location, malignancy must be evaluated for, and factors related to increased likelihood of malignancy include longstanding disease (over 20 years), location proximal to the splenic flexure, and symptomatic bowel obstruction. Because the wealth of information on stricture formation in IBD derives from CD models and studies, the remainder of this chapter will mainly focus on strictures in the context of CD pathophysiology.