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Deep Vein Thrombosis

A deep vein thrombosis, or DVT, is a blood clot that forms in the deep veins of the body, usually in the thigh, calf or pelvis. Symptoms include swelling, pain, tenderness or red skin. Other names for DVT include thromboembolism and venous thromboembolism.

Though the precise number of Americans with DVT is not known, about 1 in 1,000 people develop a DVT with symptoms each year, according to information provided by the Institute for Quality and Efficiency in Health Care (IQWiG), published by the U.S. National Library of Medicine.

While there are a few risk factors for DVT, having surgery that involves your hips or legs or experiencing an injury to your lower body are two of the most common. This is why most people receive anticoagulants such as warfarin or Xarelto to prevent blood clots after hip replacement or knee replacement surgery.

DVTs usually go unnoticed and dissolve on their own. But blood clots that remain in the vein can cause damage to the blood vessel.

Deep Vein Thrombosis
A DVT can block a vein or break free and travel to the lungs, causing a pulmonary embolism.

Symptoms and Complications

The symptoms of DVT affect the leg with the blood clot, though some people might not have any symptoms. For those people, complications of DVT might be the first symptoms they experience.

DVT Symptoms include:
  • Bulging veins
  • Discolored, red or tight skin
  • Edema or swelling
  • Tenderness and pain
  • Thickening of veins called "cords"
  • Warmth in the affected area
IVC Filter Information
Patients with IVC filters have a risk of developing DVT. The risk doubles two years after a filter is placed. Read more.
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Complications of DVT

These types of blood clots don’t cause heart attacks or strokes. But DVT can cause long-term health problems including pulmonary embolism, post-thrombotic syndrome and postphlebitic syndrome.

Pulmonary Embolism (PE)

Up to 100,000 people die of DVT or one of its more deadly but rare complications, pulmonary embolism (PE), according to the Centers for Disease Control and Prevention.

A PE occurs when a DVT travels to the lungs and blocks blood flow. The risk is greater if the DVT is in the pelvis or upper part of the leg. A pulmonary embolism requires emergency treatment.

Symptoms of PE include:
  • Feeling lightheaded or dizzy
  • Losing consciousness
  • Low blood pressure
  • Pain in the chest, especially when coughing or breathing in
  • Rapid heartbeat
  • Shortness of breath that can come on suddenly
  • Coughing up blood (rare)

Post-Thrombotic Syndrome (PTS)

A lot of people who suffer DVTs recover. But up to half may develop a complication called post-thrombotic syndrome (PTS), a condition that causes swelling, chronic pain and discomfort, according to Boston Scientific.

These symptoms are caused by damage to the valves in the veins. This causes problems with normal blood flow.

Postphlebitic Syndrome

About 20 to 50 percent of people who have DVT may suffer from postphlebitic syndrome. This usually occurs within 1 to 2 years after severe DVT, according to Merck Manual.

Symptoms of postphlebitic syndrome in the legs include:
  • Aching
  • Cramps
  • Feeling of “pins and needles”
  • Fullness
  • Heaviness
  • Pain
  • Tiredness

Symptoms usually get worse with walking or standing but may feel better with elevating the leg or sitting. These symptoms worsen with standing or walking and are relieved by rest and elevating the leg. Some people may develop a skin rash on the lower legs or ankles.

How Are DVTs Diagnosed?

Health care providers diagnose people with DVT based on symptoms and physical examination. If the provider suspects a DVT, they will order tests. Three of the most common tests are duplex ultrasound, magnetic resonance imaging and venography.

Duplex Ultrasound

A duplex ultrasound combines traditional ultrasound technology — using sound waves that echo off the body — with Doppler technology to generate a color image of blood flow. It’s noninvasive, painless and doesn’t require radiation.

Magnetic Resonance Imaging (MRI)

MRIs produce detailed images of structures inside the body, including veins, using magnetic fields. An MRI can take images of both legs at the same time. Like an ultrasound, the test is noninvasive and painless. However, some patients with implanted devices might not be able to do an MRI.


Venography is an invasive procedure that requires an injection of contrast dye into a vein in the foot. After the dye mixes with blood, the health care provider uses an x-ray to observe the blood flow. Because it’s invasive and requires radiation, venography is rarely used.

Causes and Risk Factors

There are several causes and risk factors for developing a DVT, which occurs when blood cells stick together to form a clot. Anything that affects blood circulation can form a clot, including genetics, lack of movement, injury, illness and lifestyle factors.

Some medications may also increase your risk for blood clots. For example, the U.S. Food and Drug Administration warned that women taking birth control pills containing drospirenone, such as Yaz, may have an increased risk of blood clots.

Causes of blood clots include:
  • Being in bed after an injury or fracture without encouraging blood circulation
  • Being in bed after surgery
  • Diseases that cause the blood to clot too much
  • Extended periods of bedrest without much movement
  • Major operations, particularly surgeries of the hip, leg or abdomen
  • Serious injuries to blood vessels
Risk factors for DVT include:
  • Age, people over 60 have an increased risk
  • Certain inflammatory diseases
  • Congestive heart failure (CHF)
  • Frequent travel with long stretches of sitting
  • Genetics and family history
  • High levels of cholesterol
  • History of DVT
  • Hormonal contraception (Yaz, Nuvaring)
  • Hormone replacement therapy (HRT), hormone treatment for menopause
  • Pregnancy
  • Severe obesity or being overweight
  • Smoking
  • Some cancers
  • Varicose veins

Deep Vein Thrombosis Treatment

Some people with DVT don’t require treatment. In these cases, a health care provider will monitor the clot to see if it gets any worse or goes away on its own.

Treatment for DVT focuses on stopping the growth of a blood clot, preventing the clot from traveling to the lungs and reducing the chance of a reoccurring clot.


Doctors usually recommend medications as the first line of treatment. Anticoagulants, or blood thinners, help dissolve existing clots and prevent new clots from forming. All blood thinners have a risk of causing internal bleeding.

Older medications like heparin and warfarin require blood tests to get the correct individual dose. Doctors will start with heparin and then follow up with warfarin. These medications require routine tests to monitor levels of anticoagulation and dosing may be adjusted depending on test results. Warfarin also requires dietary changes to make sure it stays effective.

Xarelto vs. Warfarin for DVT
Xarelto and other factor Xa inhibitors are as effective as or better than warfarin for preventing recurrent DVT for three months of short-term therapy.
Source: American Family Physician

Newer blood thinners called Factor Xa inhibitors such as Xarelto (rivaroxaban) and Eliquis (apixaban) don’t require blood tests, because they are a one-size-fits-all medication. They don’t require dietary changes to be effective.

In people who are at extremely high risk for PE or extremely large clots, a health care provider may recommend “clot buster” drugs called thrombolytics. These drugs include streptokinase and alteplase. Doctors deliver the drug directly into the clot through a catheter.

Compression Devices

Most people do well with anticoagulant therapy and compression or support stockings to improve blood flow and reduce swelling. The compression prevents blood from pooling in the veins and helps circulation.

After surgery, some people may use an external pneumatic compression device to prevent clots. This device resembles a boot. It applies pulses of pressure to the calf and simulates muscles pressure from walking to prevent clots and stimulate blood flow.

IVC Filters

Inferior vena cava or vena cava filters are small metal cage-like devices with spidery legs. Surgeons implant these into a vein to act as a trap for blood clots and prevent them from lodging in the heart and lungs.

Rarely, these devices may perforate the vein. Some may break, and the small fragments may lodge in the heart and other organs. Some devices have greater failure rates than others and patients should be aware of the brand their surgeon recommends.

Simple Leg Exercises While Sitting
Raise and lower heels your heels while keeping your toes on the floor
Raise and lower toes while keeping heels on the floor
Tighten and release leg muscles
Source: Centers for Disease Control and Prevention
IVC Filter Information
Although rare, patients with IVC filters may experience serious complications, such as device migration and perforation. Learn more.
View Complications

How to Prevent DVT

Because DVT can lead to several serious conditions and might not always have symptoms, the best thing for people to do is prevent them. People can prevent DVT by maintaining good cardiovascular health, a healthy body weight and avoiding inactivity.

Tips to prevent DVT include:
  • Avoid sitting for too long without moving. Periodically get up at work or at home. Taking short walks or performing activities that contract leg muscles keep the blood flowing back to the heart.
  • Being overweight or obese increases DVT risk. Make lifestyle changes to lose weight or maintain a healthy body weight. Ask your doctor for a nutritionist or dietician who can help couch you.
  • Dehydration may increase your risk for blood clots. Make sure you drink plenty of water, especially when sitting for prolonged periods.
  • If you are bedridden and can’t walk, prevent your blood from pooling and clotting by contracting leg muscles.
  • If you are bedridden in a hospital, make sure doctors and nurses take steps to prevent clots such as taking medication, wearing compression stockings or using an external pneumatic compression device to massage your calves and keep blood circulating.
  • If you are taking a long car ride, make sure you take breaks and get out to stretch and walk for a few minutes. If travelling by plane, try to stand up and walk in the aisles or pump your leg muscles.

Please seek the advice of a medical professional before making health care decisions.

Michelle Llamas, Senior Content Writer
Written By Michelle Llamas Senior Writer

Michelle Llamas has been writing articles and producing podcasts about drugs, medical devices and the FDA for nearly a decade. She focuses on various medical conditions, health policy, COVID-19, LGBTQ health, mental health and women’s health issues. Michelle collaborates with experts, including board-certified doctors, patients and advocates, to provide trusted health information to the public. Some of her qualifications include:

  • Member of American Medical Writers Association (AMWA) and former Engage Committee and Membership Committee member
  • Centers for Disease Control and Prevention (CDC) Health Literacy certificates
  • Original works published or cited in The Lancet, British Journal of Clinical Pharmacology and the Journal for Palliative Medicine
Edited By

11 Cited Research Articles writers follow rigorous sourcing guidelines and cite only trustworthy sources of information, including peer-reviewed journals, court records, academic organizations, highly regarded nonprofit organizations, government reports and interviews with qualified experts. Review our editorial policy to learn more about our process for producing accurate, current and balanced content.

  1. American Academy of Orthopaedic Surgeons. (n.d.). Deep Vein Thrombosis. Retrieved from
  2. Boston Scientific. (n.d.). DVT Complications. Retrieved from
  3. Center for Disease Control and Prevention. (n.d.). What is Venous Thromboembolism? Retrieved from
  4. Centers for Disease Control and Prevention. (n.d.). Data and Statistics on Venous Thromboembolism. Retrieved from
  5. Douketis, J.D. (2019). Chronic Venous Insufficiency and Postphlebitic Syndrome. Retrieved from
  6. Harvard Medical School. (2020, February 26). Leg clots (aka deep-vein thrombosis): an immediate and long-term health hazard. Retrieved from
  7. Institute for Quality and Efficiency in Health Care (IQWiG). (2017, March 23). Deep vein thrombosis (DVT): Overview. Retrieved from
  8. Lyon, C. et al. (2017). Rivaroxaban vs. Warfarin for Treatment of DVT and PE. Retrieved from
  9. National Heart, Lung, and Blood Institute. (n.d.). Venous Thromboembolism. Retrieved from
  10. U.S. Food and Drug Administration. (2012, April 10). FDA Drug Safety Communication: Updated information about the risk of blood clots in women taking birth control pills containing drospirenone. Retrieved from
  11. U.S. National Library of Medicine. (n.d.). Deep Vein Thrombosis. Retrieved from
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