Clinical presentation:
Adult male with abdominal pain and fever.

The view, taken supine, shows gas below the liver edge and around the colon at the hepatic flexure. A fine line, just above the hepatic flexure and the character of the gas suggests that this gas might be tracking outside the peritoneum, but the right kidney and crura of the diaphragm cannot be identified. Both sides of the wall of two loops of bowel are visible in the right iliac fossa and over the mid-lumbar spine, but the margins are less sharp than is usual and the falciform ligament (in the same area) is not shown. The ascending colon is gas-filled. Medial to this and separate from the gas in adjacent bowel is a line of gas 'lucency' that corresponds to the lateral margin of the right psoas muscle. A larger linear band of gas 'radiolucency' lies on the medial side of right psoas.

Oesophageal rupture. (case report)

Gas may track to peritoneum from a pneumomediastinum.