Deep Vein Thrombosis (DVT)

• Deep vein thrombosis (DVT) is a blood clot that forms in a deep vein, usually in the leg
• DVT can block blood flow, causing pain and swelling
• A clot can break loose and travel to the lungs, resulting in a pulmonary embolism (PE), which can be life-threatening

Epidemiology

• DVT affects about 900,000 people in the U.S. each year
• Roughly 100,000 annual deaths in the U.S. are attributed to DVT/PE
• DVT is more common in older adults, but can occur at any age
• Risk factors include:
  • Prior DVT or PE
  • Family history of DVT or PE
  • Cancer
  • Surgery
  • Trauma
  • Pregnancy
  • Use of birth control pills or hormone therapy
  • Obesity
  • Smoking
  • Prolonged immobility (e.g., long car or plane trips)

Pathophysiology

• Virchow's triad describes the three broad categories of factors contributing to thrombosis:
  • Hypercoagulability
    • Can be caused by inherited disorders, acquired conditions, or medications
  • Hemodynamic changes (stasis or turbulence)
    • Can be caused by prolonged immobility, surgery, or varicose veins
  • Endothelial injury/dysfunction
    • Can be caused by trauma, surgery, infection, or inflammation
• DVT usually starts in the valve cusps of the deep veins of the leg
• A clot can grow and extend into the larger veins of the leg
• If the clot breaks loose and travels to the lungs, it can cause a pulmonary embolism

Diagnosis

• Signs and symptoms of DVT include:
  • Pain
  • Swelling
  • Redness
  • Warmth
• Only about half of DVT patients exhibit these signs and symptoms
• A D-dimer blood test can help rule out DVT
  • D-dimer is a protein fragment produced when a blood clot breaks down
  • A negative D-dimer result indicates DVT is unlikely
  • A positive D-dimer requires further testing to confirm diagnosis
• The most common test to diagnose DVT is a duplex ultrasound
  • Ultrasound uses sound waves to create an image of the veins
  • It can show if there is a clot in the vein and how big it is
• Other tests that may be used to diagnose DVT include:
  • Venography
  • An X-ray of the veins after injecting a dye
  • Magnetic resonance imaging (MRI)
    • Uses magnetic fields and radio waves to create an image of the veins

Treatment

• The goal of treatment for DVT is to:
  • Prevent the clot from getting bigger
  • Prevent the clot from breaking loose and traveling to the lungs
  • Prevent future clots
• The most common treatment for DVT is anticoagulation with blood thinners
  • Heparin
    • An injectable anticoagulant that works quickly
    • It is usually given in the hospital
  • Warfarin
    • An oral anticoagulant that takes a few days to start working
    • Requires regular blood tests to monitor the level of anticoagulation
  • Direct oral anticoagulants (DOACs)
    • Oral anticoagulants that work quickly and do not require regular blood tests
    • Examples include dabigatran, rivaroxaban, apixaban, and edoxaban
• Other treatments for DVT include:
  • Thrombolysis
    • Involves injecting a drug to dissolve the clot
    • Used in severe cases of DVT
  • Vena cava filter
    • A filter placed in the inferior vena cava to catch clots before they travel to the lungs
    • Used in people who cannot take anticoagulants or who have recurrent pulmonary embolisms despite anticoagulation
  • Compression stockings
    • Help reduce swelling and pain in the leg
    • May also help prevent post-thrombotic syndrome

Prevention

• Several things can be done to prevent DVT:
  • Get up and move around every few hours, especially on long car or plane trips
  • Wear compression stockings, especially if at risk for DVT
  • Take anticoagulants as prescribed by a doctor
  • If having surgery, discuss ways to prevent DVT with a doctor