Computed tomographic detection of retrocrural air.

The normal prevertebral space at the level of the diaphragmatic crura contains the aorta, azygos and hemiazygos veins, lymphatics, and nerves. Three patients had gas demonstrated in the retrocrural space by computed tomography (CT). In each patient this gas was shown to represent parts of normal lung insinuated in the retrocrural space. A subsequent prospective evaluation of 100 consecutive CT examinations showed the presence of retrocrural air in 3% of patients. Retrocrural air should not be confused with free retroperitoneal air or gas caused by retroperitoneal abscesses.