Skip to content
My WebMD Sign In, Sign Up

Information and Resources

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

Exams and Tests

There is no blood test for deep vein thrombosis. After a physical exam, the doctor might do some of these tests: 

  • Doppler ultrasound: This test uses high-frequency sound waves to show the large veins in the leg and a blood clot. Painless and without complications, this is the most commonly used test to diagnose deep vein thrombosis. 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.
  • Impedance plethysmography: Electrodes are used to measure changes in blood volume within veins. Because this test does not find clots better than ultrasound and is harder to perform, it is rarely used.
  • 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.


Deep Vein Thrombosis Treatment

DVT is usually treated with blood-thinning medication  prevent more clots and to prevent the clot from traveling to the lung and causing a pulmonary embolism:

  • Warfarin (Coumadin) is a pill that thins the blood. It may take a few days to work. The dose is different for each person, and blood clotting must be checked often since diet, activity, and other drugs can affect warfarin. 
  • Enoxaparin (Lovenox) is a drug injected under the skin to thin the blood. Enoxaparin usually is only used for a short time, but it may be used over the long term in some patients with cancer.
  • Rivaroxaban (Xarelto) is also a pill. In studies on preventing deep vein thrombosis and pulmonary embolism, Xarelto was as effective as another treatment combining Lovenox and warfarin

How long someone takes blood thinners depends on 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 or it there is recurrent clot, medication may be required for more than 12 months.

Sometimes the doctor will inject clot-dissolving drugs called thombolytics directly into a clot. This has a higher chance of complications than using blood-thinning drugs.

Not all DVTs require blood thinners. Because small clots located in veins below the knee have a low risk of traveling to the lung, people with them may only be watched by the doctor. Using ultrasound tests of the veins, the clot can be monitored to see whether it is growing.

WebMD Medical Reference from eMedicineHealth

Hot Topics

Health Solutions From Our Sponsors

WebMD Video: Now Playing

Click here to wach video: Dirty Truth About Hand Washing

Which sex is the worst about washing up? Why is it so important? We’ve got the dirty truth on how and when to wash your hands.

Click here to watch video: Dirty Truth About Hand Washing

Popular Slideshows & Tools on WebMD

hands on abdomen
Can you catch one?
Woman sitting in front of UV lights
Is yours working?
woman using breath spray
What's causing yours?
womans hand on abdomen
Are you ready for baby?
MS Overview
Recognizing symptoms.
bowl of yogurt with heart shape
Eat for a healthy heart.
woman doing pushups
To help you get fit.
Colored x-ray of tooth decay
Know what to look for.
Woman sitting with child
Do you know the symptoms?
Stings, bites, burns, and more.
Allentown, PA
Are you living in one?
Thyroid exam
See how much you know.

Women's Health Newsletter

Find out what women really need.