Which condition is defined as a blood clot that forms in a vein and travels to the lungs?

• A. Aneurysm
• B. Myocardial infarction
• C. Pulmonary Embolism
• D. Deep vein thrombosis

Answer: (C)

A pulmonary embolism happens when a blood clot forms in a vein, usually a deep vein in the leg, and then breaks free to travel through the bloodstream to the lungs, where it blocks branches of the pulmonary arteries. This embolic process is what defines a PE, because the clot has moved from its vein and lodged in the lungs, unlike a deep vein thrombosis which is simply a clot in a deep vein without specifying migration. Aneurysm is dilation of a vessel, and a myocardial infarction is a heart attack caused by blockage of a coronary artery. Understanding that the clot travels to the lungs explains both the source (a venous clot) and the location of the blockage (pulmonary arteries) that leads to the clinical presentation.