Ulcerative Colitis (UC)

Ulcerative Colitis (UC)

·        = Chronic inflammation of colonic mucosa (only).  Unknown aetiology

Epidemiology

·        More common than Crohn‟s.

·        1 in 1500 in US.  Rare in developing countries

·        Peak incidence in 25 – 30 year olds

·        Smoking is protective

·        Risk in 1^st degree relatives increases 15-fold

·        F > M, W > B

Symptoms & Signs

·        Diarrhoea if disease extends above rectosigmoid junction

·        Mucus and blood per rectum

·        Urgency to defaecate

·        Abdominal pain, tenderness

·        Relapsing-remitting in 65% patients

·        If severe attack: fever, tachycardia, hypoalbuminaemia

·        May have: erythema nodosum, arthropathy, aphthous ulcers in mouth and liver complications

Investigations

·        Stool culture: exclude infectious 

·        Bloods: ­ESR and acute phase proteins

·        Possible deficiencies: Fe, Hb, albumin, electrolyte abnormalities

·        Sigmoidoscopy: red, raw, granular mucosa

·        Colonoscopy & biopsy.  Spreads from rectum to some point in colon.

Pathology

·        Macroscopic appearance: 

o   Begins in rectum and extends in continuity to left colon. 40 – 50% limited to rectosigmoid colon. 10% have pan-colitis, may also develop „backwash‟ ileitis.

o  Mild: Erythema only. Severe: Mucosal haemorrhages and broad-based ulcerations (not deep though). Normal appearance during relapses

o  Pseudopolyps: islands of remaining, regenerating mucosa

·        Microscopic appearance:

o  Mucosal inflammation only: mucosal ulcers

o  Neutrophils, plasma cells, histiocytes in lamina propria 

o  Crypt abscesses (neutrophils in crypt) suggestive of UC rather than Crohn‟s. May extend into laminar propria to produce ulcers

o  Chronically, mucosa becomes thin and atrophic

o  Distortion of crypt architecture, branching

o  Overtime ® dysplasia ® flat carcinomas (cf raised in colorectal cancer)

Differential diagnosis

·        Microscopic (lymphocytic colitis), Collangenous colitis or Crohn‟s colitis

·        Irradiation proctitis

·        Infection, IBS, or Cancer

·        CMV or herpes simplex in immunosuppressed patients

Complications

·        Anaemia due to chronic blood loss 

·         Toxic megacolon: diameter of transverse colon > 5.5 cm. Acute dilation of colon due to loss of muscle tone ® ­gas ® distension ® vascular occlusion ® necrosis. May rupture ® peritonitis. Emergency

·        ­Risk of colon carcinoma.  Key risk facts: 

o   How long have they had it (main one): 1% at 10 years, 30% at 30 years.  Require regular screening

o  How much bowel is affected: greatest in pancolitis.  Minimal with only rectal involvement

o  How well controlled is the inflammation

o  Aggressive flat lesions, infiltrates quickly into lymphatics in submucosa

·        Perforation

·        Fibromuscular strictures (check to exclude malignancy)

Treatment

·        Sulphasalazine +/- steroids (or azathioprine).  Need regular FBCs