Chest radiograph of intraperitoneal free air

This plain PA radiograph of the chest taken with the patient upright reveals a small amount of free air under the right hemidiaphragm confirming the diagnosis of a perforated abdominal viscus. The lucent, crescent-shaped free air is noted between the arrows. The dome of the liver (arrow) and the soft tissue shadow of the right hemidiaphragm (arrowhead) border the free air.