Hemopneumothorax is defined as:

• A. blood in the pleural cavity
• B. air in the pleural cavity
• C. blood in the pericardial sac
• D. fluid in the alveolar space

Answer: (A)

Hemopneumothorax is defined by the coexistence of air and blood in the pleural space. This combination typically results from chest trauma that injures both the lung (allowing air to escape into the pleural cavity) and intrathoracic vessels (causing bleeding). The option stating blood in the pleural cavity alone describes a hemothorax, not hemopneumothorax. The other choices refer to air in the pleural space (pneumothorax), blood in the pericardial sac (hemopericardium), or fluid in the alveolar space (not the pleural space).