Inflammatory Bowel Disease

“A group of inflammatory disorders of the colon and small intestine, principally Ulcerative Colitis (UC) and Crohn’s Disease (CD)”

Risk Factors

• Infective agents (e.g Mycobacteria, rotavirus, measles virus, chlamydia)
• IBD in 1st-degree relative
• Good hygiene
• Smoking (­ risk of CD; ¯ risk in UC)
• Immunosuppression

Aetiology

Not entirely understood but relies on the interaction between environmental triggers (nutrition and hygiene), genetic susceptibility, immune response and gut microflora

Pathophysiology

Altered gut microflora/overzealous immune response/genetic defect →­ bacterial colonisation → bacteria adhere to and compromise mucosal barrier → mucosal invasion → inflammation of GI mucosa

	Crohn’s Disease	Ulcerative Colitis
Distribution	Whole GI Tract	Colon only
Continuity	Skip lesions	Continous (procitis spreads backwards)
Inflammation	Transmural	Superficial
Pathology	Cobblestoning	Goblet cell loss, crypt abcesses
Granulomas	Yes	No
Smoking	Worsens disease	Protective

Clinical Presentation

• Crohn’s Disease – Diarrhoea (80%), abdo pain, weight loss. 2^o symptoms: malaise, fever, lethargy, N/V
• Ulcerative Colitis – Diarrhoea with blood/mucous, mouth ulceration, relapsing/remitting condition

Investigations

• FBC – anaemia common, ­ ESR, CRP, WCC (UC: pANCA +, CD: usually pANCA -ve)
• Stool culture – faecal calprotectin, rule out infective colitis
• Colonoscopy – superficial lesion, deep ulceration, “skip lesions”
• Abdo XR in acute exacerbations; Abdo USS determine extent of pathology

Management

• Crohn’s Disease:
  • Medical:
    • Aminosalicylates (e.g mesalazine)
    • Abx in adults with infective component (e.g metronidazole)
    • Corticosteroids (e.g prednisolone)
    • Immunomodulators (e.g azathioprine, methotrexate, 6-MP) or Biologics (Anti-TNFα: infliximab, adlimumab, certolizumab)
    • Oxygen controlled via Venturi mask
    • Ventilation
  • Surgical:
    • in ~80% CD patients
    • Minimal bowel resections only. Recurrence risk of 15%/year.

• Ulerative Colitis:
  • Medical:
    • 1st Line – Aminosalicylates for disease remission (+rectal steroids if rectal involvement)
    • UC attack/total colitis – IV hydrocortisone (+ azathioprine in recurrent disease).
  • Surgery/Rescue therapy – IV hydrocortisone + a) IV cyclosporine or b) Anti-TNFα then switch to oral prednisolone + aminosalicylate for remission

Complications

• UC Attacks
• GI Obstruction
• Toxic Megacolon
• Adhesions
• Bowel Perforation
• Non-GI complications (rheumatoid diseases, skin change, HPB complications common: sclerosing cholangitis, cholelithiasis, Fatty Liver disease)