A 32-year-old man with a severe flare of ulcerative colitis develops abdominal distension, fever, tachycardia, and absent bowel sounds. To diagnose toxic megacolon, plain abdominal radiography must show colonic dilatation exceeding which diameter?
- A 4 cm
- B 6 cm ✓
- C 9 cm
- D 12 cm
Correct answer: B. 6 cm
Explanation
Toxic megacolon is defined as systemic toxicity (fever, tachycardia, dehydration, altered sensorium) with radiographic colonic dilatation greater than 6 cm, usually involving the transverse colon, in a patient with acute colitis. The 6 cm cutoff distinguishes true megacolon from ordinary colitic gaseous distension. Management includes resuscitation, nasogastric decompression, serial radiographs, and subtotal colectomy if perforation, worsening dilatation, or failure to improve occurs.
Reference: Bailey and Love's Short Practice of Surgery, 27th ed.
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