Benign pneumoperitoneum associated with pneumomediastinum and pneumoretroperitoneum in ambulatory outpatients.

Perforation of a hollow viscus and other dangerous etiologies must always be considered in the evaluation of free peritoneal air. Pneumoperitoneum in the presence of pneumoretroperitoneum and pneumomediastinum, however, often results from air tracking from a pathologic source outside of the abdomen along the mesentery into the peritoneum. This syndrome is relatively benign, and should be considered when there are multiple sites of extraluminal air in order to minimize the risk of unnecessary exploratory laparotomy. Two cases of benign pneumoperitoneum associated with pneumomediastinum and pneumoretroperitoneum are presented.