Deep Vein Thrombosis
What is deep vein thrombosis?
Deep vein thrombosis (DVT) is a blood clot (thrombus) in a deep vein, usually in the legs.
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 ) 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
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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:
Deep vein thrombosis often does not cause symptoms or causes only minor symptoms. When symptoms occur, they include:
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:
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.
What Increases Your Risk
Many things increase your risk for deep vein thrombosis (DVT). These include:
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:
Some people have blood that clots too easily or too quickly. Problems that may cause increased clotting include:
Injury to the blood vessel wall
Blood is more likely to clot in veins shortly after they are injured. Examples include:
When To Call a Doctor
Call 911 or other emergency services if you have pulmonary embolism symptoms, including:
Call your doctor immediately if you have DVT symptoms, including:
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
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).
Your doctor will check:
Your doctor may ask:
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.
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:
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:
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:
Screening for these problems in the general population is not routinely done.
The main goals of treatment for deep vein thrombosis (DVT) are:
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.
Your doctor may also recommend self-care to relieve symptoms and prevent complications. This care includes:
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.
Preventive measures might be used before and after any procedure or event that increases your risk of deep vein thrombosis (DVT). These measures include:
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 for deep vein thrombosis (DVT) focuses on:
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:
For more information, see:
To relieve symptoms like pain and swelling, your doctor might recommend:
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.
If you have had deep vein thrombosis, these stockings might help:
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:
For treatment, you might take anticoagulants for at least 3 months. The length of time will be based on your own health, the location of the blood clot in your leg, and your risk for a pulmonary embolism. 2
In the hospital, you might be given an anticoagulant as a shot or through an IV . After you go home, you might give yourself shots for a few days. For long-term treatment, you'll likely take a pill.
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:
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.
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.
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:
Other Places To Get Help
Last Revised: October 31, 2013
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/library/calls/deepvein/index.html.
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.
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