Volvulus

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.