Deep Vein Thrombosis Explained

Understanding Deep Vein Thrombosis

What Is Deep Vein Thrombosis?

Deep vein thrombosis, 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 pulmonary embolism (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.

Other Names for Deep Vein Thrombosis

Blood clot in the legs.
Venous thrombosis.
Venous thromboembolism (VTE). This term is used for both deep vein thrombosis and pulmonary embolism.

Key Facts About Deep Vein Thrombosis

Deep vein thrombosis (DVT) is a blood clot that forms in a vein deep in the body. 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, travel through the bloodstream to the lungs, and block blood flow. This condition is called pulmonary embolism (PE). PE is a very serious condition that can cause death.
Blood clots can form in your body’s deep veins when:
- Damage occurs to a vein’s inner lining
- Blood flow is sluggish or slow
- Your blood is thicker or more likely to clot than usual
Many factors increase your risk for DVT. People who have had DVT before or have more than one risk factor are at increased risk for the condition.
Only about half the people with DVT have symptoms. These symptoms occur in the leg affected by the deep vein clot. They include swelling of the leg or along a vein in the leg, pain or tenderness in the leg, increased warmth in the area of the leg that’s swollen or in pain, and red or discolored skin on the leg.
Other symptoms may relate to PE. These may include unexplained shortness of breath, pain with deep breathing, and coughing up blood.
Your doctor will diagnose DVT based on your medical history, a physical exam, and the results from tests. He or she will identify your risk factors and rule out other causes for your symptoms.
DVT is treated with medicines that thin the blood, interfere with the blood clotting process, and dissolve blood clots. Other treatments include filters to catch blood clots and compression stockings that prevent blood from pooling and clotting.
You can take steps to prevent DVT. See your doctor regularly. Follow your treatment plan as your doctor prescribes, stay active if possible, and exercise your lower leg muscles during long trips.
Contact your doctor at once if you have any symptoms of DVT or PE.