When a blood clot forms in a major vein, located deep within the body, it is called deep vein thrombosis, or DVT (also called deep vein thrombophlebitis). Typically the clot appears in a large vein in the leg or calf, or in the pelvic area. DVT more commonly occurs in adults over age sixty, but can occur in any age group. With prompt diagnosis and treatment, most occurrences of DVT are not life threatening. However, should the clot break free and travel through the vein, it can move to a lung artery and get stuck, a condition known as a pulmonary embolism. Pulmonary embolisms can be fatal if not immediately diagnosed and treated.

Possible Causes

A combination of any of the following conditions can lead to DVT:

  • Slow blood flow through a deep vein
  • A tendency for a person’s blood to clot quickly, such as inherited or acquired hypercoagulability
  • Irritation or inflammation of the lining of the vein, such as that caused by Buerger’s Disease
  • Trauma to the deep veins

Risks for DVT include:

  • Prolonged bed rest or immobilization (such as on extended air or car trips, or due to illness)
  • Recent surgery or trauma
  • Recent pregnancy
  • Use of estrogen and birth control pills
  • A malignant tumor or cancer
  • Family history of vascular disease
  • Obesity

Many people who develop DVT have no recognizable symptoms. If symptoms are present, they may include any the following:

  • Leg pain or tenderness
  • Swelling of the leg
  • Purple discoloration of the leg or a white leg (“milk leg”)

Proper diagnosis of DVT requires a vascular diagnostic test, even after identifying the associated risk factors. Such tests may include the following:

  • Doppler ultrasound exam
  • D-timer blood test
  • Venography
  • Plethysmography

For more information on one of the above tests, please see the web page on vascular diagnostic tests.

Treatment Options

Conventional treatment of DVT involves the use of a medication called heparin, which is an anticoagulant—it prevents clotting. Heparin is received through an IV (intravenous infusion), and so requires hospitalization. An oral medication called warfarin or Coumadin is also usually taken for a number of months. A new form of heparin, called low molecular weight heparin, can be given through an injection once or twice per day and allows, in some cases, for outpatient treatment of DVT (without hospitalization).

In some cases of DVT, thrombolysis may be used. This procedure involves the use of a catheter to directly administer a clot-dissolving drug, and is described more fully on the thrombolysis page. Once the clot is gone, another procedure may be required to keep a narrowed vein open, particularly in the iliac veins, located in the pelvic area. Such procedures may include a balloon angioplasty or stenting. Please click on the name of those procedures for more information.

DVT frequently causes swelling of the affected extremity. The swollen limb should be elevated and fitted with a compression stocking. If the edema (swelling) in the leg is not controlled, the patient is at risk for developing post-phlebitic syndrome, which may cause recurrent leg ulcers, pain, and infection and can lead to significant disability. Please see post-phlebitic syndrome for more information.