Deep venous thrombosis

Alternative names

DVT; Blood clot in the legs

Definition

Deep venous thrombosis is a condition where there is a blood clot in a deep vein (a vein that accompanies an artery).

Causes, incidence, and risk factors

Deep venous thrombosis (DVT) affects mainly the veins in the lower leg and the thigh. It involves the formation of a clot (thrombus) in the larger veins of the area. This thrombus may interfere with circulation of the area, and it may break off and travel through the blood stream (embolize). The embolus thus created can lodge in the brain, lungs, heart, or other area, causing severe damage to that organ.

Risks include prolonged sitting, bedrest or immobilization (such as on long plane or car trips), recent surgery or trauma (especially hip, knee or gynecological surgery), fractures, childbirth within the last 6 months and the use of medications such as estrogen and birth control pills. Risks also include a history of polycythemia vera, malignant tumor, and inherited or acquired hypercoagulability (changes in the levels of blood clotting factors making the blood more likely to clot).

Deep venous thrombosis is more commonly seen in adults over age 60 but can occur in any age group.

Symptoms

• leg pain in one leg only
  
• leg tenderness in one leg only
  
• swelling (edema) of only one leg
  
• increased warmth of one leg
  
• changes in skin color of one leg, redness
  

Signs and tests

An examination may reveal a red, swollen, or tender leg.

The presence of deep venous thrombosis may be seen on:

• venography of the legs
  
• Doppler ultrasound exam of an extremity
  
• plethysmography of the legs
  
• D-dimer blood test
  

Many of the inherited and acquired causes of hypercoagulability (clotting tendency) can be detected by blood tests:

• antithrombin III, protein C, protein S
  
• Factor V Leyden
  
• Prothrombin 20210a mutation
  
• DIC screening
  
• lupus anticoagulant and anticardiolipin antibodies
  

Treatment