Deep vein thrombosis (DVT) is a blood clot in a vein deep in the body. Veins are blood vessels with valves that help prevent backward blood flow. Blood is pushed through the veins in legs and arms when muscles contract.
Deposits of red blood cells and clotting elements in the blood can build up in a vein. This build up leads to a blood clot. Clots usually occur in the legs, but can occur in other locations. As the clot grows, it blocks blood flow in the vein.
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Several factors contribute to clot formation, including:
- Slow blood flow, often due to lying or sitting still for a long period of time
Pooling of blood in a vein, often due to:
- Medical conditions
- Damage to valves in a vein or pressure on the valves, such as during pregnancy
- Injury to a blood vessel
- Clotting problems, which can occur due to aging or disease
- Catheters placed in a vein
Factors that may increase your chance of DVT include:
- Personal or family history of deep vein thrombosis
- Not moving your body, especially during travel
- Surgery, especially involving bones or joints
- Medical conditions, such as:
- Pregnancy, especially in women of increased age and those who are overweight, smoke, or have certain pregnancy-related conditions such as preeclampsia
- Inherited or natural genetic changes that can alter your protein levels
- Taking medications such as birth control pills, estrogen therapy, or antipsychotics
Symptoms occur when:
- The clot interferes with blood flow in the vein
- Local inflammation occurs
- A clot breaks free and travels to the lungs
Some may not have any symptoms until the clot moves to the lungs. This condition is called pulmonary embolism.
Symptoms of DVT may include:
- Swelling of a limb
- Tenderness along the vein, especially near the thigh
- Redness, paleness, or blueness of the skin of the affected limb
The doctor will ask about your symptoms and medical history. A physical exam will be done.
Your blood and blood flow may be tested. This can be done with:
- Blood tests
- Impedance plethysmography
- Duplex venous ultrasound
- Imaging tests can assess the veins. This can be done with venography.
The treatment goals are to:
- Prevent pulmonary embolism
- Stop the clot from growing
- Dissolve the clot, if possible
Treatment options include:
This may include:
- Resting in bed when necessary
- Elevating the affected limb above the heart
- Wearing compression stockings as advised by your doctor
Blood thinners are used to prevent additional clots from forming. These may be given by injection or by mouth. This treatment may be continued long-term.
In some cases, a filter may be placed in the inferior vena cava. The vena cava is a major vein. Blood from the lower body returns to the heart through this vein. The filter may trap a clot that breaks loose before it travels to the lungs.
To help reduce your chances of DVT:
- If you use them, monitor your use of blood thinners.
- Do not sit for long periods. If you are in a car or airplane or at a computer, get up often and move around.
- If you smoke, talk to your doctor about how you can successfully quit.
If you are admitted to the hospital:
- Get out of bed and walk as soon as possible during your recovery.
If you are restricted to bed:
- Do range of motion exercises in bed.
- Change your position at least every 2 hours.
- Wear compression stockings to promote venous blood flow.
- Use a pneumatic compression device. This device uses air to compress your legs and help improve venous blood flow.
- If prescribed by your doctor, take medication to reduce blood clots. This medication can reduce your chance of death due to blood clots.
Heart and Stroke Foundation of Canada
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Last reviewed November 2018 by EBSCO Medical Review Board Michael J. Fucci, DO, FACC Last Updated: 12/20/2014