The most common disease that mimics the symptoms of ulcerative colitis is Crohn's disease, as both are inflammatory bowel diseases that can affect the colon with similar symptoms. It is important to differentiate these diseases, since the course of the diseases and treatments may be different. In some cases, however, it may not be possible to tell the difference, in which case the disease is classified as indeterminate colitis.
| Crohn's Disease | Ulcerative Colitis | |
|---|---|---|
| Involves terminal ileum? | Commonly | Seldom |
| Involves colon? | Usually | Always |
| Involves rectum? | Seldom | Usually |
| Peri-anal involvement? | Commonly | Seldom |
| Bile duct involvement? | Not associated | Higher rate of Primary sclerosing cholangitis |
| Distribution of Disease | Patchy areas of inflammation | Continuous area of inflammation |
| Endoscopy | Linear and serpiginous (snake-like) ulcers | Continuous ulcer |
| Depth of inflammation | May be transmural, deep into tissues | Shallow, mucosal |
| Fistulae, abnormal passageways between organs | Commonly | Seldom |
| Biopsy | Can have granulomata | |
| Surgical cure? | Often returns following removal of affected part | Usually cured by removal of colon |
| Smoking | Higher risk for smokers | Lower risk for smokers |
| Autoimmune disease? | Generally regarded as an autoimmune disease | No consensus |
| Cancer risk? | Lower than ulcerative colitis | Higher than Crohn's |
