GI Radiology > Colon > Structural Abnormalities > Volvulus

Structural Abnormalities


Volvulus occurs when the bowel twists around about its mesentery. The classic volvulus is a sigmoid volvulus which would create a closed loop obstruction, producing a distinctive inverted U-shape radiographically. This mainly occurs in the elderly, mentally retarded, and psychiatrically disturbed. The course is typically a chronic one with intermittent acute attacks. Diagnosis can be made from plain radiographs showing ahaustral distention, air-fluid levels, and often a liver/left flank/pelvic overlap. However, if the obstruction is not complete due to a loose twisting of the bowel, the films may be normal. A barium study should be done if there is any doubt: the point of torsion looks like a hooked beak ("bird of prey" sign), and a region of chronic volvulus may appear as a "corkscrew" with localized wall thickening. Caecal or right colonic volvulus is found in younger patients, ages 30-60, and can be differentiated from a sigmoid volvulus because haustral markings can still be seen despite the bowel distention (sigmoid volvulus show no haustra). Treatment is initially the placement of a rectal tube, but surgery may be warranted if the volvulus is tight and does not unravel spontaneously.

Sigmoid Volvulus on plain film

Classic "bird of prey" appearance of Sigmoid Volvulus on Barium study (arrow)


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