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Deep Vein Thrombosis (Blood Clot in the Leg, DVT)

Exams and Tests for Deep Vein Thrombosis

After a physical exam, the doctor might do some of these tests:

  • D-dimer: This blood test measures a substance that is released as a blood clot dissolves. If this blood test is negative, and you have no risk factors for DVT, then it is unlikely that you have a blood clot.
  • Doppler ultrasound: This test uses high-frequency sound waves to show the large veins in the leg and any blood clots. Painless and without complications, this is the most commonly used test to diagnose DVT. But sometimes the test can miss a clot, especially in the smaller veins.
  • Venography: A liquid dye is injected into the veins. It highlights blockage of blood flow by a clot on an image of the legs. This is the most accurate test, but also the most uncomfortable and invasive. It is rarely done today because of the availability of better ultrasound machines.
  • CT scan: This is a type of X-ray that gives a very detailed look at the leg veins in cross section and can detect clots. It is rarely used for DVT as it is more difficult to interpret and is time consuming. The CT scan is more useful for finding blood clots in the lung.
  • Magnetic Resonance Venography: Though very accurate, this test is usually reserved for patients in whom venography is needed but can’t be done for some reason like an allergy to the contrast dye.


Deep Vein Thrombosis Treatment

DVT is usually treated with anticoagulants, often called blood-thinners. These are medications that prevent more clots and help prevent the clot from traveling to the lung and causing a pulmonary embolism:

  • Unfractionated heparin can be given as an injection or through an IV line.
  • Low-molecular weight heparins include enoxaparin (Lovenox) and dalteparin (Fragmin). These are drugs that are injected under the skin to stop new clots from forming.
  • Fondaparinux (Arixtra) is a different class of anticoagulants that is injected beneath the skin while waiting for warfarin (Coumadin) to take effect.
  • Warfarin (Coumadin) is a pill that helps prevent the blood from clotting. It may take a few days to work. It is usually started along with heparin, low molecular weight heparin or fondaparinux to give it time to become effective. The other medicine is then stopped once the warfarin starts to work. The dose is different for each person, and a blood clotting test must be checked often since diet, activity, and other drugs can affect warfarin.
  • Rivaroxaban (Xarelto), apixaban (Eliquis), and dabigatran (Pradaxa) are newer pills that can be used instead of warfarin to treat DVT.

How long someone takes blood thinners depends on many factors including how the clot developed. If there were temporary risk factors, for example a long trip or recent immobility because of injury or illness, treatment may last 3-6 months. However, if the cause is unknown, you have a condition such as cancer that can cause blood clots, or there is a recurrent clot, medication may be required for more than 12 months.

WebMD Medical Reference from eMedicineHealth

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