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Toxic megacolon is an acute, life-threatening dilation of the colon (>6 cm in transverse colon) associated with systemic toxicity due to severe inflammation involving the entire thickness of the colonic wall.

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It is a surgical emergency if unresponsive to medical therapy.

Etiopathology

Common Causes

• Inflammatory bowel disease
  • Ulcerative colitis (more common than Crohn’s)
• Infective colitis
  • Clostridioides difficile pseudomembranous colitis
  • Cytomegalovirus (CMV) colitis (immunocompromised)
• Ischemic colitis
• Other
  • Radiation colitis
  • Hirschsprung’s disease (in children, chronic form)

Pathogenesis

• Severe inflammation → loss of neuromuscular tone + mucosal ulceration → colonic dilation
• Transmural inflammation predisposes to perforation and sepsis.

Clinical Features

• Severe abdominal distension, pain
• Fever, tachycardia
• Profound diarrhea (may reduce with ileus onset)
• Signs of sepsis
• Possible peritonitis (perforation)

Diagnostic Criteria