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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 colour.
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.
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.
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.
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.
Treatment lowers 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.
There are things you can do to prevent DVT. You might 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.
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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.
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.
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.
If you have had DVT, you have a risk of a painful complication called post-thrombotic syndrome. Anticoagulant medicine may help lower the risk of this complication.
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.
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:
Blood is more likely to clot in veins shortly after they are injured. Examples include:
Call 911 or other emergency services if you have pulmonary embolism symptoms, including:
Call your doctor immediately if you have DVT symptoms, including:
Your family doctor, general practitioner, or an emergency room doctor can diagnose a blood clot (thrombus) in the leg. You may be referred to a specialist, such as an internist, a hematologist, or a surgeon—most often a vascular (blood vessel) surgeon.
When you first see the doctor, he or she will do a physical examination 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 2 weeks.
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.
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:
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.footnote 1
Other treatments may be used in the hospital for some people. These treatments include thrombolytic medicine or vena cava filters. These treatments are not common. They might be used for people who are at risk for serious problems from DVT.
For more information on these treatments, see Medications and Other Treatment.
Your doctor may also recommend self-care to relieve symptoms. This care includes:
For more information, see Home 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 hour or so on a long flight.
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:
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 non-steroidal 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.
Compression stockings are specially fitted stockings. They are tightest at the foot. They get less and less tight farther up your leg.
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.footnote 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.
Thrombolytic medicines are not commonly used to treat DVT. Although they can quickly dissolve a blood clot, thrombolytics also greatly increase the risk of serious bleeding. They might be used for people who are at risk for serious problems from DVT.
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:
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. For example, vena cava filters may be used if a person cannot take anticoagulant medicine. 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 travelling to the lungs (pulmonary embolism). But the filter doesn't stop a clot from forming.
CitationsGuyatt 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.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 ConsultedAgency 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 (2014). Medical Letter on Drugs and Therapeutics, 56(1454): 103–108. http://secure.medicalletter.org/TML-article-1454a. Accessed October 22, 2014.Chandra D, et al. (2009). Travel and risk for venous thromboembolism: Meta-analysis. Annals of Internal Medicine, 151(3): 180–190.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.Kahn SR, et al. (2014). Compression stockings to prevent post-thrombotic syndrome: A randomised placebo-controlled trial. Lancet, 383(9920): 880–888. DOI: http://dx.doi.org/10.1016/S0140-6736(13)61902-9. Accessed December 31, 2014.Kahn SR, et al. (2014). The postthrombotic syndrome: Evidence-based prevention, diagnosis, and treatment strategies. A scientific statement from the American Heart Association. Circulation, 130(18): 1636–1661. DOI: 10.1161/CIR.0000000000000130. Accessed April 28, 2015.Kearon C, et al. (2012). Antithrombotic therapy for VTE disease. Chest, 141(2, Suppl): e419S–e494S.Kearon C, et al. (2016). Antithrombotic therapy for VTE disease: CHEST guideline and expert panel report. Chest, 149(2): 315–352. DOI: 10.1016/j.chest.2015.11.026. Accessed March 1, 2016.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. BMJ Clinical Evidence. Available online: http://www.clinicalevidence.com.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.Waldron B, Moll S (2014). A patient's guide to recovery after deep vein thrombosis or pulmonary embolism. Circulation, 129(17): e477–e479. DOI: 10.1161/CIRCULATIONAHA.113.006285. Accessed October 24, 2014.
Current as of: March 4, 2020
Author: Healthwise StaffMedical Review: E. Gregory Thompson MD - Internal MedicineAdam Husney MD - Family MedicineKathleen Romito MD - Family MedicineJeffrey S. Ginsberg MD - Hematology
Current as of: March 4, 2020
Author: Healthwise Staff
Medical Review:E. Gregory Thompson MD - Internal Medicine & Adam Husney MD - Family Medicine & Kathleen Romito MD - Family Medicine & Jeffrey S. Ginsberg MD - Hematology
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