Closed-loop obstruction of the small bowel: CT and sonographic appearance.

Two patients with closed loop obstruction diagnosed by CT and sonography are reported. Abdominal radiograph was nonspecific. The characteristic CT and sonographic features included (a) isolated conglomerate of dilated, fluid-filled bowel loops; (b) fixation of these "U" shaped distended loops; (c) thickened bowel wall; and (d) extraluminal fluid.