Which statement correctly distinguishes thrombus from embolus?

• A. A thrombus travels through the bloodstream; an embolus forms in a vessel.
• B. A thrombus forms in a vessel; an embolus travels elsewhere.
• C. They are the same thing.
• D. Both are infectious.

Answer: (B)

Thrombus vs embolus centers on where the clot forms and whether it moves. A thrombus is a clot that develops in place within a blood vessel or the heart and can block the vessel at that site. An embolus is material that travels through the bloodstream to lodge in a distant location, causing a blockage there. Often a piece of a thrombus can break free and become an embolus, traveling to occlude another vessel. The other statements don’t fit because they either describe movement incorrectly, claim they’re the same, or misclassify them as infectious.