Which description best defines a pulmonary embolism?

• A. Air in the pleural space
• B. Blood clot to the lungs
• C. Fluid in the alveoli
• D. Collapsed lung

Answer: (B)

A pulmonary embolism is a blockage in the pulmonary arteries caused by material that travels from elsewhere in the body, most often a blood clot that has originated in a deep vein and moved to the lungs. This obstruction hinders blood flow to parts of the lung, creating a mismatch between ventilation and perfusion and potentially causing sudden shortness of breath and chest pain. Therefore, describing a pulmonary embolism as a blood clot traveling to and blocking the lungs best captures what this condition is.

The other descriptions aren’t about this vascular blockage: air in the pleural space describes a pneumothorax, which is a collapse of the lung due to air in the pleural space; fluid in the alveoli points to pulmonary edema or infection with fluid buildup; a collapsed lung is typically a pneumothorax or severe atelectasis rather than an embolism.