Clots can form in superficial veins and in deep veins. Blood clots with inflammation in superficial veins (called superficial thrombophlebitis or phlebitis) rarely cause serious problems. But clots in deep veins (deep vein thrombosis) require immediate medical care.

These clots are dangerous because they can break loose, travel through the bloodstream to the lungs, and block blood flow in the lungs (pulmonary embolism). Pulmonary embolism is often life-threatening. DVT can also lead to long-lasting problems. DVT may damage the vein and cause the leg to ache, swell, and change color.

Blood clots most often form in the calf and thigh veins, and less often in the arm veins or pelvic veins. This topic focuses on blood clots in the deep veins of the legs , but diagnosis and treatment of DVT in other parts of the body are similar.

Each year in the United States, between 350,000 and 600,000 people get a blood clot in the legs or in the lungs.¹

What causes deep vein clots to form?

Blood clots can form in veins when you are inactive. For example, clots can form if you are paralyzed or bedridden or must sit while on a long flight or car trip. Surgery or an injury can damage your blood vessels and cause a clot to form. Cancer can also cause DVT. Some people have blood that clots too easily, a problem that may run in families.

What are the symptoms?

Symptoms of DVT include swelling of the affected leg. Also, the leg may feel warm and look redder than the other leg. The calf or thigh may ache or feel tender when you touch or squeeze it or when you stand or move. Pain may get worse and last longer or become constant.

If a blood clot is small, it may not cause symptoms. In some cases, pulmonary embolism is the first sign that you have DVT.

How is deep vein thrombosis diagnosed?

If your doctor suspects that you have DVT, you probably will have an ultrasound test to measure the blood flow through your veins and help find any clots that might be blocking the flow. Other tests, such as a venogram, are sometimes used if ultrasound results are unclear. A venogram is an X-ray test that takes pictures of the blood flow through the veins.

How is it treated?

Treatment begins right away to reduce the chance that the blood clot will grow or that a piece of the clot might break loose and flow to your lungs.

Treatment for DVT usually involves taking blood thinners ( anticoagulants ) such as heparin and warfarin (Coumadin, for example). Heparin is given through a vein (intravenously, or IV) or as an injection. Warfarin is given as a pill. Treatment usually involves taking blood thinners for at least 3 months to prevent existing clots from growing.

Your doctor also may recommend that you prop up or elevate your leg when possible, take walks, and wear compression stockings. These measures may help reduce the pain and swelling that can happen with DVT.

How can deep vein thrombosis be prevented?

There are things you can do to prevent DVT. After surgery, you can take an anticoagulant medicine to prevent blood clots. You might also wear compression stockings. You can try to get up and out of bed as soon as possible after an illness or surgery. If you are sitting for a long time, like during a long flight, you can exercise your legs to help blood flow.

Frequently Asked Questions

Learning about deep vein thrombosis:	What is deep vein thrombosis? What causes it? What increases my risk for deep vein thrombosis? How can DVT be prevented?
Being diagnosed:	How is deep vein thrombosis diagnosed?
Getting treatment:	How is deep vein thrombosis treated? What medicines can I take for it? Are there other treatments?
Living with deep vein thrombosis:	What can I do at home for deep vein thrombosis? How do I take warfarin safely? How do I take blood thinners other than warfarin safely?

Health Tools

Health Tools help you make wise health decisions or take action to improve your health.


	Actionsets are designed to help people take an active role in managing a health condition.
	Blood Thinners Other Than Warfarin: Taking Them Safely
	Compression Stockings: How to Use Them
	Warfarin: Taking Your Medicine Safely

Cause

Deep vein thrombosis (DVT) is a blood clot in a deep vein, usually in the legs. Things that lead to a blood clot in a vein include:

Slowed blood flow, which can happen when you're not active for long periods of time.
Abnormal clotting problems, which make the blood clot too easily or too quickly.
Injury to the blood vessels, because blood is more likely to clot in veins shortly after they are injured.

Symptoms

Deep vein thrombosis often does not cause symptoms or causes only minor symptoms. When symptoms occur, they include:

Swelling.
Warmth.
Pain or tenderness. The pain may be in the calf or thigh and may be present only when the affected area is touched or when standing or walking.
Redness.

Other problems may cause symptoms like those of DVT. So diagnosing DVT can be difficult. These problems include less serious problems like cellulitis or a pulled muscle.

Symptoms of pulmonary embolism

Sometimes life-threatening pulmonary embolism is the first sign that you have DVT. Pulmonary embolism is the sudden blockage of an artery in the lung. Symptoms of pulmonary embolism include:

Sudden shortness of breath.
Chest pain that may get worse with a deep breath.
A cough that may bring up blood.
A fast heart rate.
Fainting.

What Happens

Pulmonary embolism

When you have deep vein thrombosis (DVT), the main goal of treatment is to prevent the blood clot from growing or moving to the lungs. If a blood clot breaks loose, it can travel to the lungs and block blood flow ( pulmonary embolism ). A pulmonary embolism is an emergency. Treatment for DVT lowers your risk for this problem.

The risk of a pulmonary embolism can depend on the location of the blood clot. A pulmonary embolism is more likely if a blood clot is at or above the knee than if it is in the calf. But a blood clot in a calf also has a chance of causing a pulmonary embolism.

For more information, see the topic Pulmonary Embolism.

Risk of more blood clots

After the first time you have deep vein thrombosis, there is a risk of having blood clots again. Your risk can depend on what caused your blood clot and how it was treated. Your doctor will treat you to try to prevent blood clots from happening again.

Post-thrombotic syndrome

If you have had DVT, you have a risk of a painful complication called post-thrombotic syndrome . You can help lower the risk of this complication with medicine and compression stockings.

What Increases Your Risk

Many things increase your risk for deep vein thrombosis (DVT). These include:

Being older than 40.
Being overweight.
Not taking anticoagulant medicine as prescribed.

Other risks include things that cause slowed blood flow, abnormal clotting, and a blood vessel injury.

Slowed blood flow

Blood does not flow normally if you are not active for long periods of time. Examples include:

Long-term bed rest, such as after a surgery, injury, or serious illness.
Sitting for a long time, especially when traveling long distances.
Leg paralysis.

Abnormal clotting

Some people have blood that clots too easily or too quickly. Problems that may cause increased clotting include:

Inherited blood-clotting problems.
Family history of close relatives, such as a sibling, who has had deep vein thrombosis or a pulmonary embolism.
Cancer and its treatment.
Blood vessel diseases, such as varicose veins, heart attack, heart failure, or a stroke.
Pregnancy. A woman's risk for developing blood clots increases both during pregnancy and shortly after delivery or after a cesarean section.
Using hormone therapy or birth control pills or patches.
Smoking.

Injury to the blood vessel wall

Blood is more likely to clot in veins shortly after they are injured. Examples include:

Recent surgery that involved the legs, hips, belly, or brain.
Having a central venous catheter during a hospital stay.
Injury, such as a broken hip.

When To Call a Doctor

Call 911 or other emergency services if you have pulmonary embolism symptoms, including:

Sudden shortness of breath.
Sharp chest pain that sometimes becomes worse with deep breathing or coughing.
Coughing up blood.
Fainting.
Rapid pulse or irregular heartbeat.
Anxiety or sweating.

Call your doctor immediately if you have DVT symptoms, including:

Swelling, warmth, or tenderness in the soft tissues of your leg. Swelling may also appear as a swollen ridge along a blood vessel that you can feel.
Pain in your leg that gets worse when you stand or walk. This is especially important if there is also swelling or redness in your leg.

Who to see

Health professionals who can diagnose a blood clot in the leg include:

To prepare for your appointment, see the topic Making the Most of Your Appointment.

Exams and Tests

First checks

When you first see the doctor, he or she will do a physical exam and ask questions about your medical history. These help your doctor decide what tests you need based on your risk for deep vein thrombosis (DVT).

Physical exam

Your doctor will check:

Your heart and lungs.
Your legs for warmth, swelling, bulging veins, or changes in skin color.

Medical history

Your doctor may ask:

Do you have any swelling or pain in your legs?
Have you had a blood clot before?
What medicines do you take?
Have you had surgery recently or have you been on any long trips lately?

Ultrasound test

Ultrasound is the main test used to help diagnose DVT. It creates a picture of the flow of blood through the veins.

If your doctor thinks you should have more tests, you might have two or three more ultrasounds over the next 7 to 10 days.

Additional tests

More tests may be used when ultrasound results are unclear. These tests often aren't needed, but they may help diagnose or exclude a blood clot in the leg. These tests may include:

If your doctor thinks you might have a pulmonary embolism , he or she may test your lungs. For more information, see the topic Pulmonary Embolism.

Blood thinner testing

If you are treated with anticoagulant medicines, you may need periodic blood tests to monitor the effects of the anticoagulant on the blood. Blood tests include:

Activated partial thromboplastin time (APTT) to monitor treatment with heparin.
Prothrombin time (PT), also referred to as INR, to monitor treatment with warfarin (Coumadin).

Tests for clotting problems

Special blood tests may help identify inherited blood-clotting problems that can increase your risk of forming blood clots or help explain why you got a blood clot. These tests check for genetic conditions or specific proteins in your blood.

Testing might be done if you have or had one or more of the following:

A blood clot in a vein that has no clear cause
A blood clot at age 45 or younger
A blood clot in a vein at an unusual location, such as the gastrointestinal region, the brain, or the arms
A first-degree family member (mother, father, brother, or sister) who has had a blood clot in a vein before age 45 or has had problems with blood clotting

Screening for these problems in the general population is not routinely done.

Treatment Overview

The main goals of treatment for deep vein thrombosis (DVT) are:

To prevent the blood clot from becoming larger.
To prevent the blood clot from traveling to the lungs ( pulmonary embolism ).
To prevent post-thrombotic syndrome , a condition that can cause pain, sores, and swelling of the affected leg.
To prevent blood clots from returning.

Medicine

DVT is usually treated with anticoagulant medicines. These medicines are often called blood thinners, but they do not actually thin the blood. They prevent blood clots by increasing the time it takes a blood clot to form. Also, anticoagulants help prevent existing blood clots from becoming larger.

You might take anticoagulants for at least 3 months. The length of time will vary based on your own health, where the blood clot is in your leg, and your risk for a pulmonary embolism.²

If your doctor thinks a clot needs to be dissolved right away, you might get thrombolytic therapy in the hospital.

Self-care

Your doctor may also recommend self-care to relieve symptoms and prevent complications. This care includes:

Walking.
Elevating your leg.
Wearing compression stockings.

For more information, see Home Treatment.

Vena cava filter

Vena cava filters are used for some people who have deep vein thrombosis. This is not a common treatment.

A vena cava filter is inserted into the vena cava, the large vein that returns blood to the heart from the abdomen and legs. This filter can prevent blood clots from traveling to the lungs (pulmonary embolism). But the filter doesn't stop a clot from forming.

For more information, see Other Treatment.

Prevention

Preventive measures might be used before and after any procedure or event that increases your risk of deep vein thrombosis (DVT). These measures include:

Taking anticoagulants to prevent a blood clot that can form after some types of surgery.
Exercising your lower leg muscles to improve circulation in your legs. Point your toes up toward your head so that the calves of your legs are stretched, then relax. Repeat. This exercise is especially important to do when you are sitting for long periods of time.
Getting up out of bed as soon as possible after an illness or surgery. It is very important to get moving as soon as you are able. If you cannot get out of bed, do the leg exercise described above every hour to keep the blood moving through your legs.
Using compression stockings to help prevent DVT if you are at an increased risk.

Compression Stockings: How to Use Them

During travel

Sitting still for a long flight or road trip raises your risk of getting blood clots. It's important to take steps to prevent blood clots when you travel, such as getting up and moving around every 30 to 60 minutes on a long flight.

In the hospital

Intermittent pneumatic compression (IPC) devices are also used to prevent DVT. These devices inflate and deflate knee-high boots, which reduces pooling of blood in the legs. IPC pumps are often used when people stay in a hospital.

Home Treatment

Home treatment for deep vein thrombosis (DVT) focuses on:

Taking anticoagulants (blood thinners) safely.
Relieving symptoms.
Wearing compression stockings.

Taking anticoagulants safely

If you take an anticoagulant medicine, also called a blood thinner, you need to take extra steps to avoid bleeding problems. These steps include:

Preventing falls and injuries.
Telling your doctors about all other medicines, supplements, and vitamins that you take.
Getting regular blood tests, if your doctor tells you to.

For more information, see:

Warfarin: Taking Your Medicine Safely.

Blood Thinners Other Than Warfarin: Taking Them Safely.

Relieving symptoms

To relieve symptoms like pain and swelling, your doctor might recommend:

Walking 5 or 6 times a day, if possible.
Elevating your leg.

If you are not taking an anticoagulant, your doctor might suggest that you take a nonsteroidal anti-inflammatory drug (NSAID), such as ibuprofen, to relieve pain. Do not take an NSAID unless your doctor tells you that it's safe for you.

Wearing compression stockings

Compression stockings are specially fitted stockings that are designed to treat or help prevent deep vein thrombosis.

Compression Stockings: How to Use Them

If you have had deep vein thrombosis, these stockings might help:

Prevent a complication called post-thrombotic syndrome .
Relieve symptoms like pain and swelling.

Medications

Anticoagulant medicines, also called blood thinners, are used to prevent and treat deep vein thrombosis (DVT).

These medicines prevent new clots from forming and prevent existing clots from getting larger. They don't break up or dissolve existing blood clots.

For prevention, anticoagulants might be used:

After some types of surgery.
If you have a high risk for pulmonary embolism .

For treatment, you might take more than one type of anticoagulant for a short time: heparin as a shot and warfarin as a pill. This ensures that your medicine starts working right away. You might take heparin for a few days. You'll likely take the pill for a few months or more.

Medicine choices

Heparin is injected. It starts working right away.

The two types of heparin are:

Unfractionated heparin. This medicine is typically used in the hospital.
Low-molecular-weight heparin. You can give yourself shots of this medicine at home.

Warfarin is a pill that you will likely take along with heparin for a few days. Then you might take warfarin for a few months or more.

Rivaroxaban is a pill given after surgery, such as hip or knee replacement, to prevent deep vein thrombosis.

Fondaparinux (Arixtra) is an injected anticoagulant. It is used only in the hospital.

Thrombolytics are used to quickly dissolve a clot in certain people. They are only used in the hospital.

How long will you need medicine?

If you're taking anticoagulants after surgery to prevent DVT, you only need the medicine for a short time. This might be 2 weeks or more, depending on the medicine and the type of surgery you had.

For treatment of deep vein thrombosis, you will likely take an anticoagulant for at least three months. You might take it longer, depending on your health.

You might take anticoagulants for a long time, maybe the rest of your life, if you:

Have had blood clots before or have cancer or other risk factors that make it likely you'll get another blood clot.
Have inherited blood-clotting problems.

Safety tips for anticoagulants

If you take an anticoagulant, you can take steps to prevent bleeding. This includes preventing injuries and getting regular blood tests if needed.

Warfarin: Taking Your Medicine Safely

Blood Thinners Other Than Warfarin: Taking Them Safely

Surgery

Surgery to remove a blood clot is rare. It's only considered if the blood clot is very large and is blocking a major blood vessel. Surgery increases the risk of forming new blood clots.

Other Treatment

Vena cava filters are used for some people who have deep vein thrombosis. This is not a common treatment.

A vena cava filter is inserted into the vena cava, the large vein that returns blood to the heart from the abdomen and legs.

This filter can prevent blood clots from traveling to the lungs ( pulmonary embolism ). But the filter doesn't stop a clot from forming.

Vena cava filters might be used if you:

Cannot take anticoagulants.
Continue to develop blood clots even though you have been taking anticoagulants.
Have recurrent blood clots and pulmonary hypertension .

For more information, see the topic Pulmonary Embolism.

Other Places To Get Help

Organizations

Vascular Disease Foundation
8206 Leesburg Pike
Suite 301
Vienna, VA 22182

Phone:	1-888-833-4463
Phone:	(703) 485-4500
Fax:	(703) 942-8097
Web Address:	www.vdf.org

The Vascular Disease Foundation is a nonprofit organization that provides information and support for patients and their families about vascular diseases. It also provides information and education for health professionals. This organization also provides public education through its press releases, website, and printed materials.

Agency for Healthcare Research and Quality: Consumers & Patients
540 Gaither Road
Suite 2000
Rockville, MD 20850

Phone:	(301) 427-1364
Web Address:	www.ahrq.gov/consumer

This Agency for Healthcare Research and Quality (AHRQ) website has evidence-based tips on staying healthy, choosing quality care, getting safe care, understanding diseases, comparing medical treatments, and more. AHRQ is part of the U.S. Department of Health and Human Services. It supports research that will help people make more informed decisions and improve the quality of health care services.

American Heart Association (AHA)
7272 Greenville Avenue
Dallas, TX 75231
Phone:	1-800-AHA-USA1 (1-800-242-8721)
Web Address:	www.heart.org

Visit the American Heart Association (AHA) website for information on physical activity, diet, and various heart-related conditions. You can search for information on heart disease and stroke, share information with friends and family, and use tools to help you make heart-healthy goals and plans. Contact the AHA to find your nearest local or state AHA group. The AHA provides brochures and information about support groups and community programs, including Mended Hearts, a nationwide organization whose members visit people with heart problems and provide information and support.

National Heart, Lung, and Blood Institute (NHLBI)
P.O. Box 30105
Bethesda, MD 20824-0105
Phone:	(301) 592-8573
Fax:	(240) 629-3246
TDD:	(240) 629-3255
Email:	nhlbiinfo@nhlbi.nih.gov
Web Address:	www.nhlbi.nih.gov

The U.S. National Heart, Lung, and Blood Institute (NHLBI) information center offers information and publications about preventing and treating: Diseases affecting the heart and circulation, such as heart attacks, high cholesterol, high blood pressure, peripheral artery disease, and heart problems present at birth (congenital heart diseases). Diseases that affect the lungs, such as asthma, chronic obstructive pulmonary disease (COPD), emphysema, sleep apnea, and pneumonia. Diseases that affect the blood, such as anemia, hemochromatosis, hemophilia, thalassemia, and von Willebrand disease.

VascularWeb
Society for Vascular Surgery
633 North Saint Clair Street, 24th Floor
Chicago, IL 60611
Phone:	1-800-258-7188
Email:	vascular@vascularsociety.org
Web Address:	www.vascularweb.org

VascularWeb is a Web site provided by the Society for Vascular Surgery. This Web site provides information about vascular conditions for patients and families. VascularWeb can help you learn about how to prevent and treat vascular diseases, learn about vascular screening, and find a vascular surgeon.

References

Citations

U.S. Department of Health and Human Services (2008). The Surgeon General's call to action to prevent deep vein thrombosis and pulmonary embolism. Available online: http://www.surgeongeneral.gov/topics/deepvein.

Guyatt GH, et al. (2012). Executive summary: Antithrombotic therapy and prevention of thrombosis, 9th ed.—American College of Chest Physicians evidence-based clinical practice guidelines. Chest, 141(2, Suppl): 7S–47S.

Other Works Consulted

Agency for Healthcare Research and Quality (2009). Your Guide to Preventing and Treating Blood Clots . (AHRQ Publication No. 08-0058-A). Rockville, MD: Agency for Healthcare Research and Quality. Available online: http://www.ahrq.gov/consumer/bloodclots.htm.

American College of Obstetricians and Gynecologists (2011). Thromboembolism in pregnancy. ACOG Practice Bulletin No. 123. Obstetrics and Gynecology, 118(3): 718–729.

Antithrombotic drugs (2011). Treatment Guidelines From The Medical Letter, 9(110): 61–66.

Chandra D, et al. (2009). Travel and risk for venous thromboembolism: Meta-analysis. Annals of Internal Medicine, 151(3): 180–190.

Goldhaber SZ (2010). Venous thromboembolism. In EG Nabel, ed., ACP Medicine, section 1, chap. 18. Hamilton, ON: BC Decker.

Guyatt GH, et al. (2012). Executive summary: Antithrombotic therapy and prevention of thrombosis, 9th ed.—American College of Chest Physicians evidence-based clinical practice guidelines. Chest, 141(2, Suppl): 7S–47S.

Lederle FA, et al. (2011). Venous thromboembolism prophylaxis in hospitalized medical patients and those with stroke: A background review for an American College of Physicians clinical practice guideline. Annals of Internal Medicine, 155(9): 602–615.

Lipe B, Ornstein DL (2011). Deficiencies of natural anticoagulants, protein C, protein S, and antithrombin. Circulation, 124(14): e365–e368.

McManus RJ, et al. (2011). Thromboembolism, search date June 2010. Online version of BMJ Clinical Evidence : http://www.clinicalevidence.com.

Rivaroxaban (Xarelto) – A new oral anticoagulant (2011). Medical Letter on Drugs and Therapeutics, 53(1371): 65–67.

Segal JB, et al. (2009). Predictive value of factor V leiden and prothrombin G20210A in adults with venous thromboembolism and in family members of those with a mutation: A systematic review. JAMA, 301(23): 2472–2485.

Snow V, et al. (2007). Management of venous thromboembolism: A clinical practice guideline from the American College of Physicians and the American Academy of Family Physicians. Annals of Internal Medicine, 146(3): 204–210.

Tapson VF, Becker RC (2007). Venous thromboembolism. In EJ Topol, ed., Textbook of Cardiovascular Medicine, 3rd ed., pp. 1569–1584. Philadelphia: Lippincott Williams and Wilkins.

Vazquez SR, Kahn SR (2010). Postthrombotic syndrome. Circulation, 121(8): e217–e219.

Credits

By	Healthwise Staff
Primary Medical Reviewer	E. Gregory Thompson, MD - Internal Medicine
Specialist Medical Reviewer	Jeffrey S. Ginsberg, MD - Hematology
Last Revised	August 17, 2012

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Last Revised: August 17, 2012

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Jeffrey S. Ginsberg, MD - Hematology

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