A blood clot that forms in a large vein, usually in the legs, is called what?

• A. Embolus
• B. Deep vein thrombosis
• C. Thrombus
• D. Vein

Answer: (B)

When a blood clot forms in a deep vein, usually in the legs, the condition is called a deep vein thrombosis. The name points to where the clot forms—the deep venous system—and what the clot is doing—thrombosis, or clot formation in place. This is distinct from an embolus, which is a clot that has broken loose and travels through the bloodstream, potentially causing a blockage elsewhere like the lungs. It’s also different from a thrombus in general, which simply means a clot formed in a vessel, without specifying the location. And a vein is just the vessel itself, not the clot. Recognizing DVT is important because a dislodged clot can lead to a pulmonary embolism, a serious complication.