Crohn Disease vs Ulcerative Colitis
Crohn Disease and Ulcerative Colitis are easy to mix up on the boards. Here's a side-by-side comparison — presentation, workup, imaging, and first-line treatment — drawn from our full outlines.
Crohn Disease vs Ulcerative Colitis at a glance
- Crohn Disease: Chronic transmural inflammation that can involve any segment of the GI tract; skip lesions and fistulizing disease.
- Ulcerative Colitis: Chronic mucosal inflammation beginning at the rectum and extending proximally in a continuous pattern.
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Side-by-side comparison
| Feature | Crohn Disease | Ulcerative Colitis |
|---|---|---|
| At a glance | Chronic transmural inflammation that can involve any segment of the GI tract; skip lesions and fistulizing disease. | Chronic mucosal inflammation beginning at the rectum and extending proximally in a continuous pattern. |
| Classic presentation | Young adult with months of crampy RLQ pain, intermittent diarrhea, weight loss, and perianal fistula or abscess.; Chronic diarrhea (often non-bloody but can be bloody if colonic); Crampy abdominal pain, especially RLQ (ileocecal disease); Weight loss, fatigue, low-grade fever; Perianal disease: fistulas, fissures, abscesses, skin tags;… | Young adult with weeks of bloody diarrhea, tenesmus, and urgency; LLQ tenderness; flexible sigmoidoscopy reveals continuous mucosal inflammation starting at the rectum.; Bloody diarrhea (HALLMARK); Tenesmus and urgency; Lower abdominal cramping, especially LLQ; Passage of mucus and pus; Fatigue, weight loss, fever in moderate/severe… |
| Workup / key labs | Composite of clinical, endoscopic, radiologic, and histologic features. Hallmarks: discontinuous inflammation, skip lesions, transmural disease, terminal ileal involvement, non-caseating granulomas (when present), fistulizing or stricturing behavior.; CBC (microcytic anemia from iron deficiency or anemia of chronic disease); CRP, ESR… | Composite of clinical (bloody diarrhea, urgency), endoscopic (continuous mucosal erythema, friability, ulceration starting at rectum), and histologic (crypt distortion, basal plasmacytosis, crypt abscesses; NO granulomas) findings, after exclusion of infection. Severity by Truelove and Witts criteria or Mayo Score.; CBC (anemia,… |
| Imaging | Ileocolonoscopy with biopsy of terminal ileum and each colonic segment — establishes diagnosis; aphthous → linear/serpiginous ulcers, cobblestoning, skip lesions, ileal involvement; CT or MR enterography — small bowel disease, fistulas, abscess, stricture; MRE preferred in young patients to limit radiation; Pelvic MRI for perianal… | Flexible sigmoidoscopy at initial presentation (often sufficient for diagnosis in mild disease and avoids perforation risk in severe disease); Full colonoscopy with biopsies once stabilized to assess extent (proctitis, left-sided colitis, extensive/pancolitis); Abdominal radiograph if severe disease — assess colonic dilation (toxic… |
| First-line treatment | Smoking cessation — single most impactful intervention; Nutritional optimization; supplement iron, B12, vitamin D; Induction: corticosteroids (prednisone, budesonide ileal-release for ileocecal disease) for acute flares — NOT for maintenance; Biologic anti-TNF — infliximab, adalimumab, certolizumab — induction and maintenance; combine… | Disease extent and severity determine therapy; Mild-moderate proctitis or distal disease: topical 5-ASA — mesalamine suppository or enema; can add oral 5-ASA; Mild-moderate extensive disease: oral 5-ASA — mesalamine, sulfasalazine, balsalazide — induction and maintenance; Moderate-severe disease: oral corticosteroids for induction;… |
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