Sigmoid volvulus

Sigmoid volvulus occurs when the bowel twists on its mesentery, which can produce severe, rapid, strangulated obstruction. There is a characteristic AXR with an 'inverted U' loop of bowel that looks a bit like a coffee bean. It tends to occur in the elderly, constipated and co-morbid patient, and is often managed by sigmoidoscopy and insertion of a flatus tube. Sigmoid colectomy is sometimes required.
If not treated successfully, it can progress to perforation and fatal peritonitis.