Pneumoperitoneum: importance of right upper quadrant features.

Supine abdominal radiographs of 59 patients with documented pneumoperitoneum were evaluated for findings of pneumoperitoneum. The commonly described signs were seen in only 17%. Localized intraperitoneal air in the right upper quadrant was the most frequent finding, seen in 49% of patients. Identification of these collections of air is dependent upon knowledge of the anatomy of the perihepatic spaces.