Pathophysiology and Diagnosis of Ulcerative Colitis and Crohn Disease

Inflammatory bowel disease (IBD) encompasses both ulcerative colitis and Crohn disease, and is characterized by recurrent bouts of inflammation of the gastrointestinal tract. IBD affects approximately 4 million people worldwide, and rates are gradually increasing. This review covers the etiology, epidemiology, definition and pathophysiology, extraintestinal manifestations, and other disease-related complications of IBD. Figures show the distribution of ulcerative colitis and Crohn disease by location, several colonoscopic photographs of patients with ulcerative colitis as well as those with Crohn disease, computed tomography images of patients with Crohn disease, small bowel follow-through and fluoroscopic spot images of a patient with chronic structuring Crohn disease, and a computed tomographic scan showing extraenteric manifestations of Crohn disease. Tables list the differential diagnosis of ulcerative colitis, types of infectious colitis, complications of IBD, diagnostic criteria of toxic colitis, physical signs of Crohn disease, differences between Crohn disease and ulcerative colitis, and common extraintestinal manifestations of IBD. This review contains 11 highly rendered figures, 7 tables, and 63 references.