Differentiating ulcerative colitis from Crohn disease

Characteristic	Ulcerative colitis	Crohn disease
Disease distribution	Colon and rectum	Commonly affects terminal ileum May involve any part of the gastrointestinal tract (ie, mouth to rectum)
Skip lesions (ie, spatially intermittent bowel inflammation)	Rare	Common
Vascularity of the mucosa	Friable mucosa with loss of vascularity	Normal vasculature adjacent to inflamed mucosa
Ulceration	Mainly mucosal Transmural only in severe colitis	Aphthous ulcers: Small discrete mucosal ulcers Transmural ulcers: Deeper ulcers that involve the colon wall
Cobblestone appearance	Not seen	Common
Stricture	Rare	Common
Fistula	Rare	Common Examples include perianal, enterocutanous, or rectovaginal fistula
Perianal disease	Rare	Common Examples include perianal fistula or deep anal fissure

Refer to UpToDate content on endoscopic diagnosis of inflammatory bowel disease for additional details.

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