Pulmonary embolism is defined as?

• A. Air in the pleural space due to trauma
• B. Fluid in the alveoli
• C. Blood clot to the lungs
• D. Pneumonia

Answer: (C)

A pulmonary embolism is a blockage of the pulmonary arteries by material that has traveled from elsewhere in the body, most often a blood clot. This embolus obstructs blood flow to portions of the lung, causing a V/Q mismatch and possible hypoxemia. The other options describe different problems: air in the pleural space is a pneumothorax, fluid in the alveoli points to edema or other alveolar filling processes, and pneumonia is an infection of the lung tissue. The defining feature of a pulmonary embolism is the obstructing material traveling to and blocking the pulmonary vessels, most commonly a clot.