Which radiographic sign is described as the coffee bean sign on abdominal imaging?

• A. Double bubble
• B. Coffee bean sign
• C. Lead pipe sign
• D. String sign

Answer: (B)

On abdominal radiographs, the coffee bean sign signals sigmoid volvulus. This occurs when the sigmoid colon twists around its mesentery, creating a markedly dilated loop whose two limbs lie pressed against each other, forming a shape that resembles a coffee bean. This classic appearance helps distinguish sigmoid volvulus from other causes of bowel gas patterns on plain films. Other signs point to different conditions: the double bubble indicates proximal small-bowel obstruction such as duodenal atresia in neonates; the lead pipe sign reflects chronic ulcerative colitis with loss of haustrations; and the string sign denotes Crohn disease with a narrowed terminal ileum. Recognizing the coffee bean sign directs you to consider sigmoid volvulus as the diagnosis.