Deep vein thrombosis (throm-BO-sis), or DVT, is a
blood clot that forms in a vein deep in the body. Blood clots occur when blood
thickens and clumps together.
Most deep vein blood clots occur in the lower leg or
thigh. They also can occur in other parts of the body.
A blood clot in a deep vein can break off and travel
through the bloodstream. The loose clot is called an embolus. When the clot
travels to the lungs and blocks blood flow, the condition is called
embolism (PULL-mun-ary EM-bo-lizm), or PE.
PE is a very serious condition. It can damage the
lungs and other organs in the body and cause death.
Blood clots in the thigh are more likely to break
off and cause PE than blood clots in the lower leg or other parts of the body.
Blood clots also can form in the veins closer to the
skin's surface. However, these clots won't break off and cause PE.
The animation below shows a deep vein blood clot.
Click the "start" button to play the animation. Written and spoken explanations
are provided with each frame. Use the buttons in the lower right corner to
pause, restart, or replay the animation, or use the scroll bar below the
buttons to move through the frames.
The animation shows how a blood clot
in a deep vein of the leg can break off, travel to the lungs, and block blood