A 65-year-old woman with progressive constipation and lower abdominal distension undergoes a single-contrast barium enema. There is abrupt obstruction at the rectosigmoid junction with a 'bird's beak' or 'ace of spades' tapering of the barium column. Which diagnosis does this represent?
- A Sigmoid volvulus ✓
- B Diverticular stricture
- C Colonic carcinoma
- D Colonic intussusception
Correct answer: A. Sigmoid volvulus
Explanation
The 'bird's beak' or 'ace of spades' sign, where barium tapers to a point at the site of torsion, is the classic barium enema appearance of sigmoid volvulus. The twisted segment narrows progressively toward the point of torsion. Colonic carcinoma shows an irregular apple-core lesion with shouldering, not a smooth bird's beak. Diverticular stricture shows smooth narrowing over a longer segment with spasm. Intussusception shows a coil-spring or cup-shaped filling defect, not a beaked taper.
Reference: Gore and Levine's Textbook of Gastrointestinal Radiology, 4th ed.
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Written and medically reviewed by the StethoPrep medical team.