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 features

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