Abdominal radiographs of 11 patients with hydropneumoperitoneum were reviewed. The centrally located air collection was noted in nine of the 11 patients. In the other two patients with a large amount of fluid in the pelvis, the air bubble was located in the upper abdomen. In two patients, the edge of the centrally located large air bubble was ringed by a number of small bubbles. The falciform ligament was demonstrated in five. Air-fluid levels were seen in the upper abdomen in six patients in whom upright films of the abdomen were obtained. Hydropneumoperitoneum should be suspected in supine abdominal radiographs when one recognizes a large central air collection with or without surrounding small air bubbles.
