Patients with established, complete, simple, distal small bowel obstruction usually have the following findings on plain and upright abdominal radiographs:

A. Distended small bowel identifiable by the valvulae conniventes.

B. Multiple air-fluid levels

DISCUSSION: Abdominal x-ray examination of patients with intestinal obstruction usually reveals abnormally large quantities of gas in the bowel. One can usually identify distended small intestine or colon. Gas in the small bowel outlines the valvulae conniventes, which usually occupy the entire transverse diameter of the bowel image. Colonic haustral markings occupy only a portion of the transverse diameter of the bowel. Typically, the small bowel pattern occupies the more central portion of the abdomen, whereas the colon shadow is on the periphery of the abdominal files or in the pelvis. Patients with mechanical small intestinal obstruction usually have minimal colonic gas, if any.