What Is Deep Vein Thrombosis?
Deep vein thrombosis (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 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.
- Sometimes, blood clots can form from no known cause.
Many factors increase your risk for deep vein thrombosis (DVT). They include:
- A history of DVT.
- Disorders or factors that make your blood thicker or more likely to clot than normal. Certain inherited blood disorders will do this. This also is true of hormone therapy or birth control pills.
- Injury to a deep vein from surgery, a broken bone, or other trauma.
- Slow blood flow in a deep vein from lack of movement. 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.
- Pregnancy and the first six weeks after giving birth.
- Recent or ongoing treatment for cancer.
- A central venous catheter. This is a tube placed in a vein to allow easy access to the bloodstream for medical treatment.
- Being older than 60 (although DVT can occur at any age).
- Being overweight or obese.
Your risk for DVT increases if you have more than one of the risk factors listed above.