Hemothorax is defined as which of the following?

• A. Accumulation of blood and fluids in the pleural cavity preventing full lung expansion.
• B. Air in the pleural cavity.
• C. Infection of the pleural lining.
• D. Fluid in the alveolar sacs.

Answer: (A)

Hemothorax involves blood in the pleural space, the area between the lung and chest wall. When blood collects there, it takes up space and compresses the lung, preventing it from fully expanding and causing shortness of breath. This condition is distinct from a pneumothorax, where air is in the pleural space, and from a pleural effusion that is fluid other than blood. It’s also not about fluid in the alveolar sacs, which points to problems like pulmonary edema rather than the pleural space. In practice, management focuses on draining the blood from the pleural space and treating the source of bleeding.