Medically Fit For Exams
Medically Fit For Exams

Crohn's Disease


  • A subset of inflammatory bowel disease (IBD)
  • A disease characterised by inflammation throughout the GI tract, from mouth to anus


Risk factors

  • Family history
  • Smoking


Differential diagnoses

  • Ulcerative colitis
  • Colorectal cancer
  • Coeliac disease
  • Peptic ulcer
  • GORD
  • Appendicitis
  • IBS
  • Food allergy/intolerance



  • 5-7 per 100,000
  • Affects slightly more women than men



  • Genetic
  • Autoimmune response to GI tract
    • Potentially is a dysregulated response to normal gut flora
  • Mainly Th1 and Th17 mediated


Clinical features

  • Diarrhoea, which may be bloody
  • Abdominal pain, right iliac fossa, can mimic appendicitis (colicky if obstruction)
  • Bloating
  • Weight loss
  • Anal and perianal lesions
  • Anal/enteric fistulae
  • Hypotension and tachycardia
  • Palpable mass in right iliac fossa (terminal ilium ulcer)
  • Steatorrhoea (small bowel involvement)
  • Clubbing
  • Lethargy



  • Affects entire length of GI tract, typically in patchy, discontinuous pattern
  • Transmural – affects full thickness of bowel wall
  • Oedema in mucosa and sub-mucosa
  • Typically affects terminal ilium
  • Many macrophages in bowel wall – activates Th1 differentiation – is a cycle
  • Goblet cells present (are reduced in UC)
  • Haemorrhagic ulcers – may start small, but become large and deep
  • Fibrous strictures may cause partial blockage
    • Dilation of normal bowel proximal to this
  • Mesenteric lymph node enlargement
  • Non-caseating granulomas in bowel wall and mesenteric lymph nodes (about 60% of cases)



  • Colonoscopy
  • Endoscopy
  • PR



  • Many will have bowel resections, but this is not curative, as disease may go on to affect other parts of the GI tract
  • May have stoma
  • Immunomodulators
    • Prednisolone
  • 5-aminosalicylic acid



  • Is incurable, but doesn’t significantly shorten life expectancy
Crohn's disease.docx
Microsoft Word document [14.6 KB]

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