Inflammatory Bowel Disease
Inflammatory Bowel Disease (IBD) refers to chronic, relapsing inflammation of the gastrointestinal tract, mainly encompassing
Ulcerative Colitis (UC) and Crohn’s Disease (CD).
It results from a dysregulated immune response in genetically predisposed individuals, triggered by environmental factors 🌍.
⚙️ Pathophysiology
- 🧬 Immune dysregulation: Excessive T-cell activation → cytokine release (TNF-α, IL-12, IL-23) → chronic inflammation.
- 🌱 Environmental triggers: Smoking 🚬 worsens Crohn’s but protects against UC.
- 👨👩👧 Genetics: Strong family history; mutations (e.g. NOD2 in Crohn’s).
- 💩 Microbiome imbalance: Altered gut flora contributes to inflammation.
📊 Comparison: Crohn’s vs Ulcerative Colitis
| Feature |
🌿 Crohn’s Disease |
🌹 Ulcerative Colitis |
| Distribution |
Mouth → anus (“skip lesions”). Terminal ileum common. |
Colon + rectum only. Continuous from rectum proximally. |
| Depth |
Transmural (full thickness) 🔥 |
Mucosal only 🌸 |
| Symptoms |
Diarrhoea (± bloody), abdominal pain, weight loss, fistulas, strictures. |
Bloody diarrhoea, urgency, tenesmus, abdo cramping. |
| Extra-intestinal |
Arthritis 🦴, erythema nodosum 🌸, pyoderma gangrenosum, uveitis 👁️, gallstones, kidney stones. |
PSC 🧪, arthritis, erythema nodosum, pyoderma gangrenosum, uveitis. |
| Complications |
Fistulas, strictures, malabsorption, abscesses. |
Toxic megacolon, colorectal cancer risk. |
| Surgery |
Not curative (recurrence common). |
Colectomy = curative ✅ |
🩺 Clinical Features
- 💩 GI: Chronic diarrhoea, abdominal pain, rectal bleeding, weight loss.
- 🌍 Systemic: Fatigue, fever, anaemia.
- ⚠️ Red flags: Severe bloody diarrhoea, toxic megacolon, sepsis.
- 👁️🦴 Extra-intestinal: Joints, eyes, skin, liver (PSC).
🔬 Investigations
- 🩸 Bloods: FBC (anaemia, ↑ platelets), CRP/ESR (inflammation), LFTs (esp. ALP if PSC).
- 💩 Stool: Faecal calprotectin ↑, exclude infections (C. diff, cultures).
- 📹 Endoscopy: Colonoscopy with biopsy (diagnosis + histology: granulomas in Crohn’s, crypt abscesses in UC).
- 🖼️ Imaging: MRI/CT enterography (Crohn’s small bowel involvement), AXR for toxic megacolon.
🛠️ Management
- Induction of remission:
- 💊 Corticosteroids (prednisolone, budesonide).
- 💉 Biologics for severe/refractory disease (anti-TNF e.g. infliximab, adalimumab; vedolizumab).
- Maintenance of remission:
- 🌹 UC: Aminosalicylates (mesalamine, sulfasalazine).
- 🌿 Crohn’s: Immunomodulators (azathioprine, 6-MP, methotrexate).
- Continue biologics if needed.
- Surgery:
- UC: colectomy is curative.
- Crohn’s: surgery for complications (strictures, fistulas).
- Supportive: Nutrition 🥗, smoking cessation 🚭, vaccination 💉, osteoporosis prevention, psychological support 🧠.
⚠️ Complications
- 🔄 Relapsing-remitting flares → chronic disability.
- 🧪 Colorectal cancer risk (screening colonoscopy after 8–10 yrs disease).
- 🌡️ Acute severe UC → toxic megacolon, perforation.
- 🚑 Crohn’s → strictures, fistulas, abscesses.
📚 Teaching Pearls
💡 Key Exam Clues:
– Crohn’s = transmural, skip lesions, perianal disease, fistulas.
– UC = continuous from rectum, mucosal only, bloody diarrhoea.
– Smoking 🚬 worsens Crohn’s, protects UC.
– Surgery cures UC, not Crohn’s.
– Always exclude infection (esp. C. diff) before starting steroids or biologics.
