| Characteristic | Ulcerative colitis | Crohn disease |
| Disease distribution | | - Commonly affects terminal ileum
- May involve any part of the gastrointestinal tract (ie, mouth to rectum)
|
| Skip lesions (ie, spatially intermittent bowel inflammation) | | |
| 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 | | |
| Stricture | | |
| Fistula | | - Common
- Examples include perianal, enterocutanous, or rectovaginal fistula
|
| Perianal disease | | - Common
- Examples include perianal fistula or deep anal fissure
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