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Venous thrombus and embolus

Cross-section of a vein, showing blood cells, a blood clot (thrombus), and a piece of the blood clot (embolus) that has broken off the thrombus and is moving through the vein

A thrombus is a blood clot that forms in a vein.

An embolus is anything that moves through the blood vessels until it reaches a vessel that is too small to let it pass. When this happens, the blood flow is stopped by the embolus. An embolus is often a small piece of a blood clot that breaks off (thromboembolus). It may also be fat, air, amniotic fluid, a tumor, or a foreign substance such as talc, iodine, cotton, or a tiny piece of catheter tube.

Current as of: April 9, 2019

Author: Healthwise Staff
E. Gregory Thompson MD - Internal Medicine
Martin J. Gabica MD - Family Medicine
Adam Husney MD - Family Medicine
Jeffrey S. Ginsberg MD - Hematology