4th Year MBBS
GIT
Inflammatory Bowel Disease: Ulcerative Colitis and Crohn Disease
A rapid-revision synthesis connecting pathogenesis, morphology, clinical presentation, diagnosis, pharmacotherapy, complications and surgery in one relationship-based framework. :contentReference[oaicite:0]{index=0}
1. THE TOPIC IN ONE CONNECTED FLOW
Inflammatory bowel disease develops when genetic susceptibility, environmental influences, intestinal microbes and an abnormal mucosal immune response combine to produce persistent intestinal inflammation. The depth and distribution of this inflammation then determine whether the patient develops the typical pattern of ulcerative colitis or Crohn disease, as well as the characteristic complications and treatment needs.
Genetics + environment + microbiota
Abnormal mucosal immune response
Persistent cytokine-driven tissue injury
UC: continuous, rectum-to-colon, mainly mucosal
Crohn: skip lesions, any GI site, transmural
Diarrhea, pain, bleeding, weight loss
Stool exclusion + inflammation markers + colonoscopy/biopsy ± imaging
Anti-inflammatory / immune therapy ± surgery → control disease and prevent complications
2. KEY CLINICAL CONNECTIONS
UC: Mucosal Injury → Bleeding
Continuous superficial colonic inflammation → friable mucosa and ulceration → bloody diarrhea, urgency and tenesmus.
Severe inflammation → impaired colonic neuromuscular function → marked dilatation → toxic megacolon.
Crohn: Transmural Injury → Structural Complications
Full-thickness inflammation → deep fissures and fibrosis → stricture and obstruction.
Penetrating inflammation → tract formation → fistula or abscess.
Drug Target → Clinical Benefit
Aminosalicylates → reduce mucosal inflammatory activity → useful especially in UC.
Anti-TNF / anti-integrin therapy → block inflammatory signalling or lymphocyte trafficking → control more active disease; infection risk remains important.