What radiographic sign on upright chest radiograph suggests pneumoperitoneum?

• A. Free intraperitoneal air under the diaphragms
• B. Enlarged cardiac silhouette
• C. Pulmonary edema
• D. Calcified granuloma

Answer: (A)

Free intraperitoneal air collecting under the diaphragms on an upright chest radiograph is the sign that suggests pneumoperitoneum. In the upright position, any free gas rises and appears as a radiolucent area beneath one or both diaphragms, often outlining the liver margin. This direct indication comes from air in the peritoneal cavity, typically due to a perforated abdominal viscus.

The other findings point to different issues: an enlarged cardiac silhouette suggests cardiomegaly; pulmonary edema shows fluid-related markings in the lungs; calcified granuloma is a calcified lung nodule. If only a small amount of air is present, CT or special radiographs can be more sensitive, but subdiaphragmatic free air on an upright view remains the classic clue.