INFLAMMATORY BOWEL DISEASES: DIFFERENTIAL DIAGNOSIS OF CROHN'S DISEASE AND ULCERATIVE COLITIS
Keywords:
Inflammatory bowel disease, Crohn's disease, ulcerative colitis, differential diagnosis, ileocolonoscopy, transmural inflammation, skip lesions, IBD-unclassified, ASCA, p-ANCA.Abstract
Background: Crohn's disease and ulcerative colitis are the two principal forms of inflammatory bowel disease (IBD), sharing overlapping symptoms of chronic diarrhea, abdominal pain, and rectal bleeding but differing fundamentally in anatomical distribution, depth of inflammation, and complication profile, such that correct differentiation is essential to guide treatment and prognosis.
Methods: This narrative review synthesizes current evidence on the clinical, endoscopic, histological, and serological differentiation of Crohn's disease and ulcerative colitis, drawing on major gastroenterology reference guidelines and recent comparative reviews of both conditions.
Results: Crohn's disease can affect any segment of the gastrointestinal tract from mouth to anus in a discontinuous, "skip lesion" pattern with transmural inflammation that predisposes to fistula, stricture, and abscess formation, whereas ulcerative colitis is confined to the colon and rectum, producing continuous, mucosa-limited inflammation beginning at the rectum. Ileocolonoscopy with segmental biopsy remains the diagnostic cornerstone for both conditions, with cross-sectional small-bowel imaging added when Crohn's disease is suspected; despite a thorough work-up, approximately 10 to 15% of patients with isolated colitis cannot be definitively classified and are labelled as having IBD-unclassified. Histological and serological findings, including granulomas and ASCA positivity in Crohn's disease versus crypt abscesses and p-ANCA positivity in ulcerative colitis, provide supportive but not individually definitive evidence.
Conclusion: Because Crohn's disease and ulcerative colitis require different surgical thresholds, carry different complication risks, and respond somewhat differently to certain therapies, systematic application of endoscopic, histological, and, where needed, radiological criteria remains essential for accurate differentiation, an approach that is both feasible and important to apply consistently in resource-limited settings such as Uzbekistan, where ileocolonoscopy with biopsy is the most widely available and highest-yield diagnostic tool.
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