Deep Vein Thrombosis

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 pulmonary 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 veins closer to the skin's surface. However, these clots won't break off and cause PE.

What Causes Deep Vein Thrombosis?

Blood clots can form in your body's deep veins if:

• Damage occurs to a vein's inner lining. This damage may result from injuries caused by physical, chemical, or biological factors. Such factors include surgery, serious injury, inflammation, and an immune response.
• Blood flow is sluggish or slow. Lack of motion can cause sluggish or slow blood flow. This may occur after surgery, if you're ill and in bed for a long time, or if you're traveling for a long time.
• Your blood is thicker or more likely to clot than normal. Certain inherited conditions (such as factor V Leiden) increase blood's tendency to clot. This also is true of treatment with hormone therapy or birth control pills.

What Are the Signs and Symptoms of Deep Vein Thrombosis?

The signs and symptoms of deep vein thrombosis (DVT) may be related to DVT itself or to pulmonary embolism (PE). See your doctor right away if you have signs or symptoms of either condition. Both DVT and PE can cause serious, possibly life-threatening complications if not treated.

Deep Vein Thrombosis

Only about half of the people who have DVT have signs or symptoms. These signs and 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, which you may feel only when standing or walking
  
• Increased warmth in the area of the leg that's swollen or in pain
  
• Red or discolored skin on the leg

Pulmonary Embolism

Some people don't know they have DVT until they have signs or symptoms of PE. Signs and symptoms of PE include:

• Unexplained shortness of breath
  
• Pain with deep breathing
  
• Coughing up blood

Rapid breathing and a fast heart rate also may be signs of PE.

Information provided by National Heart Lung and Blood Institute