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Definition, epidemiology, and risk factors in inflammatory bowel disease

Authors
Mark A Peppercorn, MD
Adam S Cheifetz, MD
Section Editor
Paul Rutgeerts, MD, PhD, FRCP
Deputy Editor
Shilpa Grover, MD, MPH

INTRODUCTION

Inflammatory bowel disease (IBD) is comprised of two major disorders: ulcerative colitis (UC) and Crohn disease (CD). These disorders have both distinct and overlapping pathologic and clinical characteristics.

The definition, epidemiology, and role of environmental factors in Crohn disease and ulcerative colitis in adults will be reviewed here. Similar issues in children and adolescents, the role of genetic factors, clinical manifestations, diagnosis, and treatment of IBD are discussed separately. (See "Genetic factors in inflammatory bowel disease" and "Clinical manifestations, diagnosis and prognosis of Crohn disease in adults" and "Overview of the medical management of mild to moderate Crohn disease in adults" and "Overview of the medical management of severe or refractory Crohn disease in adults" and "Clinical manifestations, diagnosis, and prognosis of ulcerative colitis in adults" and "Management of severe ulcerative colitis in adults" and "Approach to adults with steroid-refractory and steroid-dependent ulcerative colitis".)

DEFINITIONS

Inflammatory bowel disease (IBD) is comprised of two major disorders: ulcerative colitis and Crohn disease. Ulcerative colitis and Crohn disease have distinct pathologic and clinical characteristics but their pathogenesis remains poorly understood.

Ulcerative colitis — Ulcerative colitis is a chronic inflammatory condition characterized by relapsing and remitting episodes of inflammation limited to the mucosal layer of the colon. It almost invariably involves the rectum and typically extends in a proximal and continuous fashion to involve other portions of the colon. Different terms have been used to describe the degree of involvement [1,2].

Ulcerative proctitis refers to disease limited to the rectum

                     

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