Abdominal sonography for the diagnosis of large bowel obstruction.

To evaluate the clinical usefulness of abdominal sonography in the diagnosis of large bowel obstruction, the sonographic findings of 39 patients with a large bowel obstruction, in the form of a simple obstruction in 36 patients and a sigmoid volvulus in 3, were reviewed in comparison with their plain X-ray findings. Abdominal sonography showed a large bowel obstruction in 33 patients, and an obstructing lesion in 14 of these patients. However, in the other 6 patients, including the 3 with a sigmoid volvulus, the image was disturbed by extensive colonic gas. Although the plain abdominal X-ray films showed no gaseous colonic dilatation, isolated small bowel dilatation was seen in six patients with a large bowel obstruction proximal to the splenic flexure. In five of these six patients, abdominal sonography revealed a dilated colon filled with fluid and feculent contents which was difficult to evaluate on the plain X-ray films. Consequently, abdominal sonography was proven to be useful, especially for detecting X-ray-negative colonic dilatation.