Ischaemic Colitis

Ischaemic colitis results from transient or sustained reduction in colonic blood flow. Most disease is nonocclusive and affects watershed regions, particularly the splenic flexure and rectosigmoid junction.

Severity ranges from reversible mucosal injury to transmural gangrene.

Isolated right sided disease is clinically important because it is associated with more severe outcomes and may indicate proximal mesenteric arterial disease.

Typical presentation is sudden cramping abdominal pain followed within hours by passage of bright red or maroon blood.

Left sided disease commonly produces left lower abdominal tenderness.

Severe pain without rectal bleeding, hypotension, persistent tachycardia, peritonism or organ dysfunction should increase concern for severe or transmural ischaemia.

CT abdomen with IV contrast: first investigation in significant disease; define distribution and look for advanced ischaemic injury.

Limited colonoscopy within approximately 48 hours: confirms mucosal ischaemia when the diagnosis remains uncertain and there is no peritonitis or evidence of gangrene.

If isolated right colon disease or acute mesenteric ischaemia is suspected, perform CT angiography.

Mild disease is treated with bowel rest, IV fluid correction, optimisation of cardiac output and withdrawal of precipitating vasoconstrictive drugs where possible.

Avoid hypotension because repeated low flow insults can convert reversible injury into infarction.

Moderate or severe disease should receive broad enteric antimicrobial coverage, for example:

Ceftriaxone 2 g IV every 24 hours plus metronidazole 500 mg IV every 12 hours.

Urgent surgery is required for:

• Peritoneal signs
• Gangrene
• Perforation
• Persistent clinical deterioration
• Uncontrolled sepsis
• Massive bleeding
• Extensive right sided or pancolonic necrosis.

Resect nonviable colon. Avoid primary anastomosis when perfusion of remaining bowel is uncertain or the patient is physiologically unstable.

A healed ischaemic segment can later form a fixed symptomatic stricture. Persistent obstructive symptoms require elective segmental resection.