Deep vein thrombosis (patient information)

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Deep vein thrombosis


What are the symptoms?

What are the causes?

Who is at highest risk?

When to seek urgent medical care?


Treatment options

Where to find medical care for Deep vein thrombosis?

What to expect (Outlook/Prognosis)?

Possible complications


Deep vein thrombosis On the Web

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Videos on Deep vein thrombosis

FDA on Deep vein thrombosis

CDC on Deep vein thrombosis

Deep vein thrombosis in the news

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Directions to Hospitals Treating Deep vein thrombosis

Risk calculators and risk factors for Deep vein thrombosis

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Editor(s)-In-Chief: The APEX Trial Investigators, C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Cafer Zorkun, M.D., Ph.D. [2] Ujjwal Rastogi, MBBS [3]; Kashish Goel, M.D.; Assistant Editor(s)-In-Chief: Justine Cadet


Deep venous thrombosis (DVT) is the formation of a blood clot in one of the deep veins within the body, such as in the leg or pelvis.

What are the symptoms of Deep vein thrombosis?

What causes Deep vein thrombosis?

Deep venous thrombosis (DVT) mainly affects the large veins in the lower leg and thigh. The clot can block blood flow and cause swelling and pain. When a clot breaks off and moves through the bloodstream, this is called an embolism. An embolism can get stuck in the brain, lungs, heart or another other area that can lead to severe damage.

Blood clots may form when something causes the flow of blood in the veins to slow or change.


Who is at highest risk?

DVTs are most common in adults over age 60, but can occur at any age.

Sitting for long periods when traveling can increase the risk of DVTs. This is most likely when one or more of the risk factors listed below are also present. Risk factors include:

  • After a pacemaker catheter has been passed through the vein in the groin
  • Bedrest
  • Cigarette smoking
  • Family history of blood clots
  • Fractures in the pelvis or legs
  • Giving birth within the last 6 months
  • Heart failure
  • Obesity
  • Recent surgery (especially hip, knee, or female pelvic surgery)
  • Too many blood cells being made by the bone marrow (polycythemia vera), causing the blood to be thicker and slower than normal

You're also more likely to develop DVT if you have any of the following conditions:

When to seek urgent medical care?

Call your health care provider if you have symptoms of DVT.

Go to the emergency room or call the local emergency number (such as 911) if you have DVT and you develop chest pain, difficulty breathing, coughing blood, fainting, loss of consciousness, or other severe symptoms.


Your health care provider will perform a physical exam. The exam may show a red, swollen, or tender leg.

The following tests may be done:

  • D-dimer blood test
  • Doppler ultrasound exam of the legs
  • Plethysmography (measurement of blood flow) of the legs
  • X-rays to show veins in the affected area(venography)
  • Blood tests may be done to check if there is increased chance of blood clotting (hypercoagulability)

Such tests include:

Genetic testing to look for mutations that make you more likely to develop blood clots, such as the prothrombin G20210A mutation

This list is not all-inclusive.

Treatment options

Your doctor will give you medicine to thin your blood (called an anticoagulant). This will keep more clots from forming or old ones from getting bigger. These drugs cannot dissolve existing clots.

Heparin is usually the first drug given.

If heparin is given through a vein (IV), you must stay in the hospital. Newer forms of heparin can be given by injection once or twice a day. You may not need to stay in the hospital as long, or at all, if you are prescribed this newer form of heparin. A drug called warfarin (Coumadin) is usually started along with heparin.

Warfarin is taken by mouth. It takes several days to fully work. Heparin is not stopped until the warfarin has been at the right dose for at least 2 days. You will most likely take warfarin at least 3 months. Some people must take it for the rest of their lives, depending on their risk for another clot. When you are taking warfarin, you are more likely to bleed, even from activities you have always done.

Changing how you take your warfarin, taking certain medicines, and eating certain foods can change the way the warfarin works in your body. If this happens, you may be more likely to form a clot or have bleeding problems. Never stop taking your medicine or change the dose without talking to your doctor.

If you are taking warfarin:

  • Take the medicine just the way your doctor prescribed it
  • Ask the doctor what to do if you miss a dose
  • You will need to get blood tests often to make sure you are taking the right dose
  • You will be given a pressure stocking to wear on your leg or legs. A pressure stocking improves blood flow in your legs, and reduce *your risk for blood clots. It is important to wear these every day.

In rare cases, surgery may be needed if medicines do not work. Surgery may involve:

  • Placement of a filter in the body's largest vein to prevent blood clots from traveling to the lungs
  • Removal of a large blood clot from the vein or injection of clot-busting medicines

Medications to avoid

Patients diagnosed with deep vein thrombosis should avoid using the following medications:

  • Esterified estrogens
  • Raloxifene
    If you have been diagnosed with deep vein thrombosis, consult your physician before starting or stopping any of these medications.

Where to find medical care for Deep vein thrombosis?

Directions to Hospitals Treating Deep vein thrombosis

What to expect (Outlook/Prognosis)?

Many DVTs disappear without a problem, but they can return. Some people may have long-term pain and swelling in the leg known as post-phlebitic syndrome. Wearing tight (compression) stockings during and after the DVT may help prevent this problem.

Blood clots in the thigh are more likely to break off and cause pulmonary embolism (PE) than blood clots in the lower leg or other parts of the body.

Possible complications

A blood clot can break free in the leg and travel to the lungs (pulmonary embolus) or anywhere else in the body, and can be life threatening. Rapid treatment of DVT helps prevent this problem.

Post-phlebitic syndrome refers to long-term swelling (edema) in the leg that had the deep vein thrombosis. Changes in skin color and pain can also be present. These symptoms may be noticed right away, or may not develop for one or more years afterward. This problem is called post-thrombotic syndrome.


Wear the pressure stockings your doctor prescribed. They will improve blood flow in your legs and reduce your risk for blood clots.

Doctors may prescribe blood thinners to help prevent DVT in people at high risk, or those who are undergoing high-risk surgery.

Moving your legs often during long plane trips, car trips, and other situations in which you are sitting or lying down for long periods of time can also help prevent DVT. People at very high risk for blood clots may need heparin shots when they are on a flight that lasts longer than 4 hours.

Do not smoke. If you smoke, quit. Women who are taking birth control pills or estrogen must stop smoking.