Abstract
Answer C. Perforated abdominal viscus
The chest X-ray shows free air underneath the right hemidiaphragm. The area under the diaphragm in a chest radiograph is usually dense owing to the liver and spleen on either side. Owing to these dense structures, only the silhouette of the upper surface of the diaphragm is seen on a chest X-ray. It is important to finish a chest X-ray examination by looking under the diaphragm for the presence of free air. This sign indicates perforation of an abdominal viscus.
InnovAiT article: Interpretation of chest radiographs. DOI: 10.1177/1755738017735864.