Chronic inflammatory disorder confined to colon and rectum
Aetiology
- Same as Crohn’s - genetic predisposition, faulty immune response, dysbiosis
- Smoking protects against UC (vs aggregates Crohn's)
Pathophysiology
- Starts in rectum, moves proximally and continuously
- Only colon affected
- Inflammation is restricted to the mucosa, and results in the formation of horizontal undermining ulcers
- Mechanism same as Crohn’s
Clinical presentation
Symptoms
- Diarrhoea and bleeding
- Increased bowel frequency and urgency
- Tenesmus
- Incontinence
- Night rising
- Lower abdominal pain, especially left iliac fossa - colicky
- Proctitis can cause constipation
Extra-intestinal manifestations
- Skin - pyoderma gangrenosum, erythema nodusum
- Joints - arthritis, ank spondylitis
- Eyes - uveitis
- Oxalate renal stones
Investigations
Bloods
- ↑ CRP
- ↓ albumin
- Faecal calprotein test
AXR
- Stool absent in inflamed colon
- Mucosal oedema (‘thumb-printing’)
- In an acute flare AXR or CT can be used to assess for toxic megacolon/bowel perforation
Colonoscopy + biopsy
- Definitive investigation
Findings
- Confluent superficial inflammation extending proximally from anal margin to a ‘transition zone’
- Mucosal ulceration and thin wall
- Pseudo polyps
- Histology:
- Absence of goblet cells
- Crypt distortion and abscess
- Mucosal layer only affected
- Infiltration of monocytes/neutrophils and plasma cells
Management
Drug therapy
- 5ASA (sulphasalazine or mesalazine) - maintenance
- Corticosteroids
- Immunosuppression
- Anti-TNF
Surgery
- Complete proctocolectomy and permanent ileostomy
- Restorative proctocolectomy and pouch (younger patients)
- Subtotal colectomy with ileostomy (emergency)
Complications
- Increased risk of colorectal cancer - colonoscopy 10 years post diagnosis
- Malabsorption, malnutrition
- PSC - 80% have associated IBD (more likely to be UC)
- Toxic megacolon
- Increased risk of osteoporosis
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