A 30-year-old man with fulminant ulcerative colitis develops abdominal distension, fever of 39 degrees C, tachycardia and a raised CRP. Abdominal radiograph shows a dilated colon. What minimum colonic diameter establishes the diagnosis of toxic megacolon?

• A Greater than 4 cm
• B Greater than 12 cm
• C Greater than 9 cm
• D Greater than 6 cm ✓

Explanation

Toxic megacolon is defined as systemic toxicity (fever, tachycardia, leucocytosis, electrolyte disturbance) with radiological colonic dilatation exceeding 6 cm, usually measured at the transverse colon, in a patient with acute colitis. The 9 cm figure applies to caecal diameter in colonic pseudo-obstruction, where perforation risk rises sharply beyond that size. Management includes resuscitation, serial imaging, and colectomy for perforation, worsening dilatation or failure to improve within 24 to 48 hours.

Reference: Schwartz's Principles of Surgery, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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