Sigmoid volvulusWhat is the diagnosis?

• A massively dilated, inverted U-shaped loop of large bowel rising from the pelvis towards the upper abdomen — the coffee bean sign
• Absent haustral markings in the twisted loop
• Dilated proximal colon

The coffee bean sign is the classic plain film appearance of sigmoid volvulus — a closed-loop obstruction caused by twisting of a redundant sigmoid colon around its mesentery.

Without signs of ischaemia, endoscopic decompression is first-line. Recurrence is common, so elective resection is usually offered. CT shows the whirl of twisted mesentery and any ischaemia.