Crohn's disease vs ulcerative colitis: pathology, features and management comparison
RezzyAh, the classic inflammatory bowel disease (IBD) showdown! This is a massive topic for the UKMLA AKT, and honestly, it's one of those areas where they love to test the subtle (and not-so-subtle) differences between the two.
Think of Crohn's as the "grumpy traveler"—it can show up anywhere from the mouth to the anus and likes to skip around. Ulcerative Colitis (UC), on the other hand, is the "neat freak"—it starts at the rectum and moves continuously up the colon, never leaving a gap.
I've put together a comparison table to help you visualize these differences side-by-side.
| Feature | Crohn's Disease | Ulcerative Colitis |
|---|---|---|
| Location | Anywhere (Mouth to Anus); Terminal ileum most common | Colon only; Starts at rectum and moves proximally |
| Distribution | Skip lesions (patchy) | Continuous involvement |
| Depth | Transmural (full thickness) | Mucosal (superficial) |
| Pathology | Non-caseating granulomas, Cobblestoning | Crypt abscesses, Pseudopolyps |
| Smoking | Increases risk / worsens disease | Protective (oddly enough!) |
| Complications | Fistulas, Strictures, Malabsorption | Toxic megacolon, Primary Sclerosing Cholangitis (PSC) |
| Radiology | "String sign" (Kantor's), Rose-thorn ulcers | "Lead pipe" colon (loss of haustra) |
When it comes to management, the NICE guidelines (which the AKT follows closely) split things into inducing remission (treating the flare) and maintaining remission (keeping them well).
1. Inducing Remission
- Crohn’s: First-line is usually Glucocorticoids (oral prednisolone or IV hydrocortisone). If they have frequent flares, you might add an immunosuppressant like Azathioprine.
- UC: For mild-to-moderate disease, Aminosalicylates (5-ASA) like Mesalazine are the gold standard (topical or oral). For severe flares, you jump straight to IV steroids.
2. Maintaining Remission
- Crohn’s: Azathioprine or Mercaptopurine are common. Biologics (like Infliximab) are used if those fail.
- UC: 5-ASAs are used here too! They are great for keeping UC at bay.
3. Surgery
- UC: Surgery (Proctocolectomy) is considered curative because the disease is limited to the colon.
- Crohn’s: Surgery is not curative because the disease can just pop up elsewhere. We only operate for complications like fistulas or obstructions.
To help you remember the "look" of these conditions, let me find some pathology and radiology images for you.
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