Inflammatory bowel disease

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Quick Overview

Inflammatory bowel disease (IBD) comprises Crohn's disease (CD) and ulcerative colitis (UC), chronic relapsing-remitting inflammatory conditions affecting the GI tract. NICE NG129 provides evidence-based guidance on inducing/maintaining remission, biologics use, and monitoring complications. Key focus: distinguishing CD vs UC, escalating therapy appropriately, and surveillance for strictures, fistulae, and malignancy risk.

Core Facts & Concepts

Key Distinctions:

FeatureCrohn's DiseaseUlcerative Colitis
LocationMouth to anus (skip lesions)Colon only (continuous)
DepthTransmuralMucosa/submucosa only
SmokingWorsens diseaseProtective (paradoxically)
Fistulae/stricturesCommonRare
Malignancy riskModerateHigher (↑ with extent/duration)

Figure 1: Colonoscopy showing deep linear ulcers and cobblestone mucosa in Crohn's disease

Disease Activity Indices:

  • UC: Truelove-Witts severity (mild <4 stools/day, severe ≥6 + systemic toxicity)
  • CD: Harvey-Bradshaw Index (clinical score without endoscopy)

📊 Critical Numbers:

  • Malignancy surveillance colonoscopy: Start at 10 years post-diagnosis for extensive colitis
  • Toxic megacolon: Colon diameter >6cm on AXR
  • Thiopurine metabolites: Target 6-TGN 235-450 pmol/8×10⁸ RBC

Figure 2: Abdominal X-ray showing dilated transverse colon greater than 6cm in toxic megacolon

Problem-Solving Approach

Inducing Remission (NICE NG129):

  1. Mild-moderate UC: Topical (rectal) aminosalicylate (5-ASA) ± oral 5-ASA
  2. Moderate-severe UC: IV corticosteroids (hydrocortisone 100mg QDS)
    • If no response in 72 hours → consider rescue therapy (infliximab or ciclosporin) or colectomy
  3. Mild-moderate CD: Consider exclusive enteral nutrition (first-line in children) or oral prednisolone
  4. Moderate-severe CD: Corticosteroids ± add azathioprine for maintenance

Maintaining Remission:

  • UC: Oral/rectal 5-ASA (not steroids long-term)
  • CD: Azathioprine/mercaptopurine or methotrexate (steroids NOT for maintenance)

🚩 Red Flags for Biologics (Anti-TNF):

  • Disease refractory to conventional therapy
  • ≥2 acute severe UC flares in 12 months
  • Steroid-dependent disease
  • Perianal fistulising CD

⚠️ Warning: Screen for latent TB (CXR + IGRA) before starting anti-TNF therapy

Analysis Framework

Surgical Indications:

IndicationCrohn's DiseaseUlcerative Colitis
EmergencyPerforation, obstruction, toxic megacolonToxic megacolon, perforation, haemorrhage
ElectiveStrictures, fistulae, abscessFailed medical therapy, dysplasia/cancer
Surgery typeResection (recurrence common)Colectomy (curative)

Monitoring Complications:

  • Strictures: MR enterography for small bowel (CD)
  • Fistulae: MRI pelvis ± examination under anaesthesia
  • Malignancy: Colonoscopy q1-2 years after 10 years (extensive disease)
  • Nutritional: Check vitamin B12 (terminal ileum CD), vitamin D, iron

Visual Aid

Nutritional Support in CD:

  • Exclusive enteral nutrition: Polymeric formula for 6-8 weeks (induces remission, especially paediatric)
  • Parenteral nutrition if intestinal failure/short bowel post-resection

Key Points Summary

UC affects colon only (continuous); CD affects any GI site (skip lesions, transmural)

Acute severe UC: IV hydrocortisone → if no response at 72h consider infliximab/ciclosporin/colectomy

Maintenance: 5-ASA for UC; thiopurines/methotrexate for CD (NEVER long-term steroids)

Biologics (anti-TNF): For steroid-dependent, refractory disease, or fistulising CD; screen for TB first

Surveillance colonoscopy: Start at 10 years post-diagnosis for extensive colitis; q1-2 years thereafter

Toxic megacolon: Colon >6cm on AXR; medical emergency requiring urgent surgical review

Exclusive enteral nutrition: First-line for inducing remission in paediatric CD

Practice Questions: Inflammatory bowel disease

Test your understanding with these related questions

A 44-year-old woman presents with recurrent episodes of severe right upper quadrant pain after eating fatty foods. The pain radiates to her right shoulder and lasts several hours. What is the most likely diagnosis?

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Flashcards: Inflammatory bowel disease

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A plain abdominal X ray for Hirschsprungs Disease will demonstrate _____

TAP TO REVEAL ANSWER

A plain abdominal X ray for Hirschsprungs Disease will demonstrate _____

dilated loops of bowel with fluid levels

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