What is the most common form of colonic volvulus?
Sigmoid volvulus accounts for about three fourths of cases of colonic volvulus. Radiographically, an inverted U-shaped loop of dilated colon extends far out of the pelvis into the upper abdomen. If the inner walls of the ascending and descending portions of the sigmoid loop are apposed to each other, a thick soft tissue stripe is seen radiating toward the pelvis. This has been described as resembling a coffee bean. The colon and even the small bowel proximal to the twist also are dilated.