Definition

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.

Deep Vein Thrombosis

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Causes

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:
  • Immobility
  • 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

Risk Factors

Risk factors for DVT include:

• Personal or family history of deep vein thrombosis
• Hospitalization
• Not moving your body, especially during travel
• Surgery, especially involving bones or joints
• Medical conditions, such as:
  • Varicose veins
  • Cancer
  • Heart failure
  • Heart attack
  • Inflammatory bowel disease
  • Blood disorders
  • Blood poisoning, also called sepsis
• Obesity
• Pregnancy
• Inherited or natural genetic changes that can alter your protein levels
• Taking medications such as birth control pills, estrogen therapy, or antipsychotic medicine

Symptoms

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 patients may not have any symptoms until the clot moves to the lungs. This condition is called pulmonary embolism.

Symptoms of DVT may include:

• Pain
• Swelling of a limb
• Tenderness along the vein, especially near the thigh
• Warmth
• Redness, paleness, or blueness of the skin of the affected limb

Diagnosis

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
• You may have images taken. This can be done with venography.

Treatment

Treatment aims to:

• Prevent pulmonary embolism
• Stop the clot from growing
• Dissolve the clot, if possible

Treatments include:

Prevention

General prevention measures include:

• Having tests that 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.
• Do not smoke.

If you are admitted to the hospital, talk to your doctor about how to prevent blood clots, such as:

• 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 two 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.