The erect chest x-ray shows a continuous diaphragm sign, indicating the presence of pneumoperitoneum.

Free intraperitoneal air outlining the right and left hemidiaphragms plus the central tendon of diaphragm gives rise to the appearance of continuous diaphragm.

The patient had a diverticular perforation and underwent emergency surgery.

The chest x-ray also shows a right para-tracheal opacity which turned out to be due to venous confluence on CT chest.

Continuous diaphragm sign can also be seen in pneumomediastinum when the air outlines the upper surface of the entire diaphragm.