Inflammatory Bowel Disease
Inflammatory Bowel Disease (IBD) refers to chronic, relapsing inflammation of the gastrointestinal tract, mainly encompassing
Ulcerative Colitis (UC) and Crohnโs Disease (CD).
It results from a dysregulated immune response in genetically predisposed individuals, triggered by environmental factors ๐.
โ๏ธ Pathophysiology
- ๐งฌ Immune dysregulation: Excessive T-cell activation โ cytokine release (TNF-ฮฑ, IL-12, IL-23) โ chronic inflammation.
- ๐ฑ Environmental triggers: Smoking ๐ฌ worsens Crohnโs but protects against UC.
- ๐จโ๐ฉโ๐ง Genetics: Strong family history; mutations (e.g. NOD2 in Crohnโs).
- ๐ฉ Microbiome imbalance: Altered gut flora contributes to inflammation.
๐ Comparison: Crohnโs vs Ulcerative Colitis
| Feature |
๐ฟ Crohnโs Disease |
๐น Ulcerative Colitis |
| Distribution |
Mouth โ anus (โskip lesionsโ). Terminal ileum common. |
Colon + rectum only. Continuous from rectum proximally. |
| Depth |
Transmural (full thickness) ๐ฅ |
Mucosal only ๐ธ |
| Symptoms |
Diarrhoea (ยฑ bloody), abdominal pain, weight loss, fistulas, strictures. |
Bloody diarrhoea, urgency, tenesmus, abdo cramping. |
| Extra-intestinal |
Arthritis ๐ฆด, erythema nodosum ๐ธ, pyoderma gangrenosum, uveitis ๐๏ธ, gallstones, kidney stones. |
PSC ๐งช, arthritis, erythema nodosum, pyoderma gangrenosum, uveitis. |
| Complications |
Fistulas, strictures, malabsorption, abscesses. |
Toxic megacolon, colorectal cancer risk. |
| Surgery |
Not curative (recurrence common). |
Colectomy = curative โ
|
๐ฉบ Clinical Features
- ๐ฉ GI: Chronic diarrhoea, abdominal pain, rectal bleeding, weight loss.
- ๐ Systemic: Fatigue, fever, anaemia.
- โ ๏ธ Red flags: Severe bloody diarrhoea, toxic megacolon, sepsis.
- ๐๏ธ๐ฆด Extra-intestinal: Joints, eyes, skin, liver (PSC).
๐ฌ Investigations
- ๐ฉธ Bloods: FBC (anaemia, โ platelets), CRP/ESR (inflammation), LFTs (esp. ALP if PSC).
- ๐ฉ Stool: Faecal calprotectin โ, exclude infections (C. diff, cultures).
- ๐น Endoscopy: Colonoscopy with biopsy (diagnosis + histology: granulomas in Crohnโs, crypt abscesses in UC).
- ๐ผ๏ธ Imaging: MRI/CT enterography (Crohnโs small bowel involvement), AXR for toxic megacolon.
๐ ๏ธ Management
- Induction of remission:
- ๐ Corticosteroids (prednisolone, budesonide).
- ๐ Biologics for severe/refractory disease (anti-TNF e.g. infliximab, adalimumab; vedolizumab).
- Maintenance of remission:
- ๐น UC: Aminosalicylates (mesalamine, sulfasalazine).
- ๐ฟ Crohnโs: Immunomodulators (azathioprine, 6-MP, methotrexate).
- Continue biologics if needed.
- Surgery:
- UC: colectomy is curative.
- Crohnโs: surgery for complications (strictures, fistulas).
- Supportive: Nutrition ๐ฅ, smoking cessation ๐ญ, vaccination ๐, osteoporosis prevention, psychological support ๐ง .
โ ๏ธ Complications
- ๐ Relapsing-remitting flares โ chronic disability.
- ๐งช Colorectal cancer risk (screening colonoscopy after 8โ10 yrs disease).
- ๐ก๏ธ Acute severe UC โ toxic megacolon, perforation.
- ๐ Crohnโs โ strictures, fistulas, abscesses.
๐ Teaching Pearls
๐ก Key Exam Clues:
โ Crohnโs = transmural, skip lesions, perianal disease, fistulas.
โ UC = continuous from rectum, mucosal only, bloody diarrhoea.
โ Smoking ๐ฌ worsens Crohnโs, protects UC.
โ Surgery cures UC, not Crohnโs.
โ Always exclude infection (esp. C. diff) before starting steroids or biologics.
