AKT · Gastroenterology/Colon & rectum

Ulcerative colitis

Continuous mucosal inflammation from the rectum proximally (smoking protects)

Overview

A chronic relapsing inflammatory bowel disease — CONTINUOUS mucosal inflammation starting at the rectum and extending proximally (proctitis → left-sided → pancolitis), limited to the colon. Bloody diarrhoea with mucus, urgency and tenesmus. Smoking PROTECTS (the opposite of Crohn). Managed with aminosalicylates first-line, escalating to steroids/biologics; acute severe colitis and toxic megacolon are emergencies; long-standing disease needs cancer surveillance.

Recognise

BLOODY diarrhoea with mucus, urgency, tenesmus, lower abdominal pain; relapsing-remitting
CONTINUOUS inflammation from the rectum, MUCOSAL only, limited to the colon; lead-pipe colon (loss of haustra) on chronic imaging
Extra-intestinal: primary sclerosing cholangitis (UC-specific association), arthritis, erythema nodosum, pyoderma gangrenosum, uveitis; smoking PROTECTS

Red flags

ACUTE SEVERE colitis (Truelove-Witts: ≥6 bloody stools/day + systemic upset) → admit for IV steroids; rescue ciclosporin/infliximab; watch for toxic megacolon/perforation
Long-standing colitis → colorectal cancer surveillance colonoscopy (from ~10 years)

Differentials & how to tell them apart

Crohn diseaseskip lesions, transmural, perianal, NON-bloody, smoking worsens; UC is continuous/mucosal/bloody, smoking protects

Infective colitis (incl. C. difficile)acute, stool culture/toxin positive — exclude before/with a flare

Ischaemic colitisolder, watershed, vascular

Colorectal cancerolder, mass, weight loss — and a complication of long-standing UC

Ulcerative colitis — continuous granular, friable, ulcerated mucosa (endoscopy)
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Investigations

Faecal CALPROTECTIN, FBC/CRP; COLONOSCOPY + biopsy (continuous inflammation from rectum, crypt abscesses, mucosal only); AXR in acute severe disease (exclude toxic megacolon); LFTs (PSC).

Management

Aminosalicylate (mesalazine) first-line to induce/maintain; escalate to steroids/biologics

1Mild-moderate: aminosalicylate (mesalazine — topical for proctitis, add oral for extensive disease) to induce and maintain remission; corticosteroids if 5-ASA insufficient.Gate: ACUTE SEVERE colitis (≥6 bloody stools/day + systemic upset, Truelove-Witts) → ADMIT for IV corticosteroids, with rescue ciclosporin/infliximab and colectomy if not improving by day 3–5; watch for TOXIC MEGACOLON (do not over-investigate with colonoscopy in severe disease)
2Maintenance with 5-ASA ± thiopurine/biologic; colectomy is curative for refractory disease/dysplasia; CRC surveillance colonoscopy from ~10 years; manage PSC.

Aminosalicylate (mesalazine — topical then oral) — FIRST-LINE to induce and maintain remission in mild-moderate disease

Corticosteroids (topical/oral/IV) — to induce remission if 5-ASA insufficient; not for maintenance

Thiopurine (azathioprine) / biologics / JAK inhibitor — maintenance if steroid-dependent/refractory; severe disease

IV ciclosporin / infliximab — rescue therapy in acute severe colitis not responding to IV steroids

Key points

Continuous-from-rectum + mucosal + BLOODY diarrhoea + smoking PROTECTS = UC. Mesalazine first-line. Acute severe colitis = IV steroids + rescue therapy; toxic megacolon is the dreaded complication. PSC is the UC-specific association; cancer surveillance from 10 years.

Monitor & prognosis

Calprotectin/symptoms; acute severe disease in hospital; CRC surveillance; LFTs (PSC).

Relapsing; colectomy curative; cancer risk with extent/duration.

Source: NICE NG130; CKS Ulcerative colitis