A 32-year-old woman with a severe flare of ulcerative colitis develops fever, tachycardia, abdominal distension, and tenderness over the transverse colon. Abdominal radiograph is performed to assess for toxic megacolon. What is the minimum colonic diameter that defines this complication?

• A Any segment greater than 12 cm
• B Caecum greater than 6 cm
• C Transverse colon greater than 9 cm
• D Transverse colon greater than 6 cm ✓

Explanation

Toxic megacolon is defined by systemic toxicity (fever, tachycardia, raised CRP, dehydration) together with total or segmental non-obstructive colonic dilatation exceeding 6 cm, classically measured in the transverse colon where gas rises on a plain erect film. The 9 cm figure applies to caecal diameter in Ogilvie's syndrome and colonic pseudo-obstruction, a common trap. Management includes resuscitation, serial imaging, and colectomy if perforation or deterioration occurs.

Reference: Bailey and Love Short Practice of Surgery, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.