Intussusception: characteristic radiolucencies on the abdominal radiograph.

Six hundred and twenty-five sets of supine and erect abdominal radiographs of 288 patients with the confirmed diagnosis of intussusception (315 episodes) and 310 patients without intussusception were reviewed retrospectively to determine the characteristic radiographic features of intussusception. Among the patients with intussusception, 155 episodes (49%) showed a soft tissue mass and nearly half of these (71) showed characteristic radiolucencies (target, crescentic, or amorphous) in the soft tissue mass. Thirty-five episodes showed the radiolucencies on both the supine and erect radiographs; in 16 cases the type of radiolucency differed on the two films. In patients without intussusception, abnormal radiolucencies were seen in only seven cases (2.3%). Computed tomography performed prospectively in five patients showed the radiolucencies in the soft tissue mass to be intussuscepted mesenteric fat. We conclude that abnormal radiolucencies in the soft tissue mass on plain radiographs are characteristic of intussusception.