Deep vein thrombosis, or DVT, is a blood clot that forms in a vein deep in the body. Most deep vein clots occur in the lower leg or thigh. If the vein swells, the condition is called thrombophlebitis. A deep vein thrombosis can break loose and cause a serious problem in the lung, called a pulmonary embolism.

Sitting still for a long time can make you more likely to get a DVT. Some medicines and disorders that increase your risk for blood clots can also lead to DVTs. Common symptoms are

• Warmth and tenderness over the vein
• Pain or swelling in the part of the body affected
• Skin redness

Treatment includes medicines to ease pain and inflammation, break up clots and keep new clots from forming. Keeping the affected area raised and applying moist heat can also help. If you are taking a long car or plane trip, take a break, walk or stretch your legs and drink plenty of liquids.

Blood clots include deep vein thrombosis (DVT) and pulmonary embolism (PE), which are serious, but preventable medical conditions. DVT is a blood clot in a deep vein, usually in the lower leg, thigh, or pelvis, but it can occur in other places, like the arm. If a DVT breaks off and travels through the bloodstream to the lungs, it causes a PE, which is a blockage of arteries in the lungs. Together, DVT and PE are known as venous thromboembolism (VTE). It is important to know about VTE because it can happen to anybody and can cause serious illness, disability, and even death. Many VTE events are preventable and if found early, can be treated.

Key Facts

• Knowing the signs and symptoms of deep vein thrombosis (DVT) and pulmonary embolism (PE) is critical for early detection.
• Signs and symptoms of DVT include swelling, pain, tenderness, and redness of the skin in the affected area of the body.
• PEs can occur without any signs of a DVT and they can be deadly.
• Signs and symptoms of a PE include difficulty breathing, chest pain, irregular heartbeat, and coughing up blood.
• Seek immediate medical care if you experience symptoms of a DVT or PE.

Hospitalization, Surgery, and Injuries

Injury to a vein, often caused by fractures, severe muscle injury, or major surgery (particularly involving the abdomen, pelvis, hip, or legs), can increase the risk for developing blood clots. A clot that occurs from a hospitalization, surgery, or other healthcare treatment or procedure is called a healthcare-associated venous thromboembolism (HA-VTE). About 50% of blood clots are healthcare-associated.

Prolonged Immobility

People who have slowed blood flow caused by confinement to a bed (such as due to a medical condition or after surgery), limited movement (such as a cast on a leg to help heal an injured bone), sitting for a long time, especially with crossed legs (such as when traveling), or paralysis, are at increased risk for blood clots.

Increased Estrogen

Increased estrogen can increase the risk of developing blood clots. Increased estrogen can occur in women taking birth control pills, receiving hormone replacement therapy, or who are pregnant (including up to 6 weeks after giving birth).

Cancer and Chronic Illness

Patients are at higher risk for blood clots if they have a chronic disease, such as heart disease, lung disease, or inflammatory bowel disease. People with cancer and those receiving cancer treatment also have an increased risk for developing a blood clot. In some cases, blood clots may be the first indication of undiagnosed cancer.

History of Blood Clots

Other factors that may increase a person’s risk for developing a blood clot include previous blood clots, family history of blood clots, and certain genetic (inherited) clotting disorders.

Other Risk Factors

Age (risk increases as age increases), obesity, smoking, or a catheter located in a central vein may also increase a person’s risk for blood clots. Speak to your doctor about your risk for developing blood clots today!

Prevention Tips

• Move around as soon as possible after having been confined to a bed, such as after surgery, illness, or injury.
• If you are at risk for blood clots, talk with your doctor about specific ways you can prevent them from occurring. Compression devices (such as compression stockings) and medication (anticoagulants) are two ways to prevent DVT.
• When sitting for long periods of time, such as when traveling for more than four hours, get up and walk around every 1 to 2 hours, exercise your legs while you are sitting, and wear loose-fitting clothes.
• You can reduce your risk for blood clots by maintaining a healthy weight and avoiding a sedentary lifestyle. In other words, exercise improves blood flow, so don’t be a couch potato.
• It’s especially important to know your risk for blood clots and follow your doctor’s recommendations based on your individual risk factors.

Deep Vein Thrombosis and Pulmonary Embolism (DVT/PE) are often underdiagnosed and serious, but preventable medical conditions.

Deep vein thrombosis (DVT) is a medical condition that occurs when a blood clot forms in a deep vein. These clots usually develop in the lower leg, thigh, or pelvis, but they can also occur in the arm.

It is important to know about DVT because it can happen to anybody and can cause serious illness, disability, and in some cases, death. The good news is that DVT is preventable and treatable if discovered early.

Complications of DVT

The most serious complication of DVT happens when a part of the clot breaks off and travels through the bloodstream to the lungs, causing a blockage called pulmonary embolism (PE). If the clot is small, and with appropriate treatment, people can recover from PE. However, there could be some damage to the lungs. If the clot is large, it can stop blood from reaching the lungs and is fatal.

In addition, one-third to one-half of people who have a DVT will have long-term complications caused by the damage the clot does to the valves in the vein called post-thrombotic syndrome (PTS). People with PTS have symptoms such as swelling, pain, discoloration, and in severe cases, scaling or ulcers in the affected part of the body. In some cases, the symptoms can be so severe that a person becomes disabled.

For some people, DVT and PE can become a chronic illness; about 30% of people who have had a DVT or PE are at risk for another episode.

Risk Factors for DVT

Almost anyone can have a DVT. However, certain factors can increase the chance of having this condition. The chance increases even more for someone who has more than one of these factors at the same time.

Following is a list of factors that increase the risk of developing DVT:

• Injury to a vein, often caused by:
  • Fractures,
  • Severe muscle injury, or
  • Major surgery (particularly involving the abdomen, pelvis, hip, or legs).

• Slow blood flow, often caused by:
  • Confinement to bed
    (e.g., due to a medical condition or after surgery);
  • Limited movement (e.g., a cast on a leg to help heal an injured bone);
  • Sitting for a long time, especially with crossed legs; or
  • Paralysis.

• Increased estrogen, often caused by:
  • • Birth control pills
    • Hormone replacement therapy, sometimes used after menopause
    • Pregnancy, for up to 3 months after giving birth

• Certain chronic medical illnesses, such as:
  • Heart disease
  • Lung disease
  • Cancer and its treatment
  • Inflammatory bowel disease (Crohn’s disease or ulcerative colitis)

• Other factors that increase the risk of DVT include:
  • Previous DVT or PE
  • Family history of DVT or PE
  • Age (risk increases as age increases)
  • Obesity
  • A catheter located in a central vein
  • Inherited clotting disorders

Preventing DVT

The following tips can help prevent DVT:

• Move around as soon as possible after having been confined to bed, such as after surgery, illness, or injury.

• If you’re at risk for DVT, talk to your doctor about:
  • Graduated compression stockings (sometimes called “medical compression stockings”)
  • Medication (anticoagulants) to prevent DVT.

• When sitting for long periods of time, such as when traveling for more than four hours:
  • Get up and walk around every 1 to 2 hours.
  • Exercise your legs while you’re sitting by:
    • Raising and lowering your heels while keeping your toes on the floor
    • Raising and lowering your toes while keeping your heels on the floor
    • Tightening and releasing your leg muscles
  • Wear loose-fitting clothes.

• You can reduce your risk by maintaining a healthy weight, avoiding a sedentary lifestyle, and following your doctor’s recommendations based on your individual risk factors.

Symptoms

Know the Signs. Know your Risk. Seek Care.

Everybody should know the signs and symptoms of DVT/PE, their risk for DVT/PE, to talk to their health care provider about their risk, and to seek care immediately if they have any sign or symptom of DVT/PE.

DVT

About half of people with DVT have no symptoms at all. The following are the most common symptoms of DVT that occur in the affected part of the body:

• Swelling
• Pain
• Tenderness
• Redness of the skin

If you have any of these symptoms, you should see your doctor as soon as possible.

PE

You can have a PE without any symptoms of a DVT.

Signs and symptoms of PE can include:

• Difficulty breathing

• Faster than normal or irregular heart beat
• Chest pain or discomfort, which usually worsens with a deep breath or coughing
• Coughing up blood
• Very low blood pressure, lightheadedness, or fainting

If you have any of these symptoms, you should seek medical help immediately.

Diagnosis of DVT and PE

The diagnosis of DVT or PE requires special tests that can only be performed by a doctor. That is why it is important for you to seek medical care if you experience any of the symptoms of DVT or PE.

Treatments for DVT and PE

DVT

Medication is used to prevent and treat DVT. Compression stockings (also called graduated compression stockings) are sometimes recommended to prevent DVT and relieve pain and swelling. These might need to be worn for 2 years or more after having DVT. In severe cases, the clot might need to be removed surgically.

PE

Immediate medical attention is necessary to treat PE. In cases of severe, life-threatening PE, there are medicines called thrombolytics that can dissolve the clot.  Other medicines, called anticoagulants, may be prescribed to prevent more clots from forming. Some people may need to be on medication long-term to prevent future blood clots.

Did you know?

DVT does not cause heart attack or stroke. There are two main types of blood clots.
How a clot affects the body depends on the type and location of the clot:

• A blood clot in a deep vein of the leg, pelvis, and sometimes arm, is called deep vein thrombosis (DVT). This type of blood clot does not cause heart attack or stroke.
• A blood clot in an artery, usually in the heart or brain, is called arterial thrombosis. This type of blood clot can cause heart attack or stroke.

Both types of clots can cause serious health problems, but the causes and steps you can take to protect yourself are different.

DVT may occur if the flow of blood slows down in your body’s deep veins, if something damages the blood vessel lining, or if the makeup of the blood itself changes so that blood clots form more easily.

Many factors can raise the likelihood of blood clotting in the deep veins of the legs.

• Age: DVT can occur at any age, but the chances rise as you get older.
• Family history: Some Genes you inherit may raise your likelihood of developing blood clots.
• Not moving for long periods of time: DVT can develop during a long flight or when a person is on bed rest in a nursing home, hospital setting, or after surgery. The chance of developing a blood clot is highest in the first 3 months after surgery and lowers with time. Ask your healthcare provider about prevention plans if you are scheduled for major surgery.
• Medical conditions: A blood clotting disorder, immune illnesses such as lupus, heart problems, cancer, or serious illness such as getting infected with SARS-CoV-2, the virus that causes COVID-19, can raise the likelihood of DVT.
• Sex: Women in their childbearing years are more likely than men to develop blood clots. The chance is higher for pregnant women and women who take birth control pills or get hormone therapy. After menopause, women’s risk is lower than men’s.

You may notice these symptoms of DVT around the area of a blood clot in your leg:

• Swelling
• Pain or tenderness
• Cramping, aching, or increased warmth
• Red or discolored skin

Your provider will diagnose DVT based on your symptoms, medical history, a physical exam, and various imaging or blood test results.

• D-dimer tests measure a substance in the blood that is released when the fibrin protein (proteins that help stop bleeding) in a blood clot dissolve. If the test shows high levels of the substance, you may have DVT. These tests may be used as a first step to look for signs of a blood clot in otherwise healthy people.
• Compression ultrasound looks for blood clots in the deep veins of your legs. This test uses sound waves to create pictures of blood flowing in your veins. The person doing the test may press on your veins to see whether the veins compress normally or are stiff with blood clots.
• Magnetic resonance venography uses a specialized magnet to take images of your veins. Your provider will need to give you a special dye through an intravenous tube (IV) before the test. This test is usually only used if your provider cannot diagnose DVT from the compression ultrasonography results.

Most people can treat DVT with medicines at home. Sometimes, more serious blood clots require you to stay in the hospital for treatment.

Your healthcare provider will likely prescribe blood-thinning medicine to keep blood clots from getting larger and prevent a DVT from becoming a life-threatening pulmonary embolism. If you are unable to take blood thinners, other medicines or procedures can help.

As you recover from DVT, talk to your provider about what you can do to stay healthy.

• Be aware of possible complications. A condition called post-thrombotic syndrome can develop following DVT. If you experience pain, itchiness, or swelling, tell your healthcare provider.
• Prevent a repeat DVT. Talk with your provider about your risk, get regular checkups, and take all medicines as prescribed to help lower your chance of having repeat blood clots.
• Make healthy lifestyle changes. Talk to your provider about changes you may need to make, including choosing heart-healthy foods, getting physically active, aiming for a healthy weight, and quitting smoking.
• Take care of your mental health. Anxiety, fear, and stress can be common after a blood clot. Reach out to your healthcare provider if you need support.

Lots of things can cause pain and swelling in your leg. But if your symptoms stem from a blood clot deep in your leg, it can be dangerous. Blood clots can happen to anyone, anytime. But some people are at increased risk. Taking steps to reduce your chances of a blood clot forming in your veins can help you avoid potentially serious problems.

Blood clots can arise anywhere in your body. They develop when blood thickens and clumps together. When a clot forms in a vein deep in the body, it’s called deep vein thrombosis. Deep vein blood clots typically occur in the lower leg or thigh.

“Deep vein thrombosis has classic symptoms—for example swelling, pain, warmth, and redness on the leg,” says Dr. Andrei Kindzelski, an NIH blood disease expert. “But about 30–40% of cases go unnoticed, since they don’t have typical symptoms.” In fact, some people don’t realize they have a deep vein clot until it causes a more serious condition.

Deep vein clots—especially those in the thigh—can break off and travel through the bloodstream. If a clot lodges in an artery in the lungs, it can block blood flow and lead to a sometimes-deadly condition called pulmonary embolism. This disorder can damage the lungs and reduce blood oxygen levels, which can harm other organs as well.

Some people are more at risk for deep vein thrombosis than others. “Usually people who develop deep vein thrombosis have some level of thrombophilia, which means their blood clots more rapidly or easily,” Kindzelski says. Getting a blood clot is usually the first sign of this condition because it’s hard to notice otherwise. In these cases, lifestyle can contribute to a blood clot forming—if you don’t move enough, for example. Your risk is higher if you’ve recently had surgery or broken a bone, if you’re ill and in bed for a long time, or if you’re traveling for a long time (such as during long car or airplane rides).

Having other diseases or conditions can also raise your chances of a blood clot. These include a stroke, paralysis (an inability to move), chronic heart disease, high blood pressure, surgical procedure, or having been recently treated for cancer. Women who take hormone therapy pills or birth control pills, are pregnant, or within the first 6 weeks after giving birth are also at higher risk. So are those who smoke or who are older than 60. But deep vein thrombosis can happen at any age.

You can take simple steps to lower your chances for a blood clot. Exercise your lower leg muscles if you’re sitting for a long time while traveling. Get out of bed and move around as soon as you’re able after having surgery or being ill. The more active you are, the better your chance of avoiding a blood clot. Take any medicines your doctor prescribes to prevent clots after some types of surgery.

A prompt diagnosis and proper treatment can help prevent the complications of blood clots. See your doctor immediately if you have any signs or symptoms of deep vein thrombosis or pulmonary embolism (see the Wise Choices box). A physical exam and other tests can help doctors determine whether you’ve got a blood clot.

There are many ways to treat deep vein thrombosis. Therapies aim to stop the blood clot from getting bigger, prevent the clot from breaking off and moving to your lungs, or reduce your chance of having another blood clot. NIH scientists continue to research new medicines and better treatment options.

If you think you may be at risk for deep vein thrombosis, talk with your doctor.

Clues of a Clot

Seek treatment if you have these symptoms. They may signal a deep vein clot or pulmonary embolism:

• swelling of the leg or along a vein in the leg
• pain or tenderness in the leg, which you may feel only when standing or walking
• increased warmth in the area of the leg that’s swollen or painful
• red or discolored skin on the leg
• unexplained shortness of breath
• pain with deep breathing
• coughing up blood

Pulmonary Embolism

The most dangerous complication of deep vein thrombosis (DVT) is pulmonary embolism, which occurs when an embolism travels through the heart and into the lungs. There it lodges in an artery, typically where the artery forks, and blocks blood flow. The lungs are particularly vulnerable to embolisms because all the blood in the body passes through the lungs every time it circulates. Depending on the size of the embolism and where it lodges, the result can be asymptomatic (without symptoms) or a life-threatening medical emergency in which large amounts of lung tissue, deprived of blood, die. Often not one but many embolisms shower the lungs during an episode of pulmonary embolism.

Symptoms of pulmonary embolism include:

• Lightheadedness, dizziness
• Sudden shortness of breath, either when active or when at rest
• Chest pain like that of a heart attack in the chest and possibly radiating to the shoulder, arm, neck, or jaw
• Cough with bloody sputum

Pulmonary embolisms can be fatal. If signs of a pulmonary embolism develop, medical attention should be sought immediately.

Heart Attack

Thromboembolisms can cause heart attacks as well. A clot can become lodged in one of the heart's coronary arteries (the arteries that supply the heart muscle tissue with blood) so that the tissue becomes starved of oxygen and dies. The medical term for a heart attack is myocardial infarction.

Symptoms of Heart Attack

• Pressure or squeezing pain in the center of your chest that lasts for more than a few minutes
• Pain similar to that of angina but that is generally more severe, lasts longer, and doesn't respond to rest or angina medication
• Pain that extends beyond your chest to your shoulder, arm, back, or jaw (referred pain)
• Increasing episodes of chest pain
• Prolonged pain in the upper abdomen
• Shortness of breath
• Heavy pounding of heart
• Sweating
• Sense of impending doom
• Fainting
• Nausea and vomiting

Heart attacks are medical emergencies. Anyone who might be having a heart attack should get to a hospital emergency room as quickly as possible. The sooner treatment begins, the better the chances of survival.

Stroke

A blood clot can travel to the brain and become lodged in one of its arteries. The resulting, severely reduced blood flow is called ischemia. About 83% of all strokes are ischemic. Deprived of the blood that brings them oxygen and glucose (a sugar), brain cells become stressed or damaged. The amount of damage done to brain cells depends on how long they are deprived. If it's for only a brief time, they may recover. If they are deprived of oxygen for a longer period of time (and this can mean just a few minutes) they may die, and some functions may be lost.

There are two types of ischemic stroke:

• Thrombotic stroke. A thrombus forms in one of the arteries that supplies blood to the brain. This can occur in one of the arteries of the neck as well as in the brain itself.
• Embolic stroke. A thrombus forms in another part of the body, often in the heart, and travels through the arteries until it becomes stuck in the narrower arteries of the brain.

Strokes are medical emergencies that require immediate medical attention, so it's very important to know the signs and symptoms of stroke:

• Sudden numbness, weakness, or paralysis, especially on one side of the body
• Sudden confusion or change in consciousness
• Sudden vision problems in one or both eyes
• Sudden dizziness, difficulty walking, loss of coordination
• Sudden, severe headache
• Sudden difficulty speaking or understanding speech

If you think someone is in fact having a stroke:

• Call for emergency medical help immediately.
• If the person stops breathing, begin mouth-to-mouth resuscitation.
• If he or she starts to vomit, turn their head to the side to prevent choking.
• Don't let the person eat or drink anything.

Don't wait to call for help. The success of most stroke treatments depends on how soon they are administered.

Cor pulmonale

Cor pulmonale is failure of the right side of the heart caused by prolonged high blood pressure in the pulmonary artery and right ventricle of the heart. When there is a blockage in the lung's arteries due to an embolism, blood pressure in the lungs (pulmonary resistance) increases. The heart's right ventricle, the chamber that pumps blood to the lungs, pumps harder to compensate. The overworked heart becomes enlarged, which makes it weaker. (Unlike other muscles in the body, the heart becomes weaker, not stronger, as it becomes larger.) Eventually the heart may fail to perform. Cor pulmonale is usually a chronic disease, but massive pulmonary embolism can make it acute. In the US, about 50,000 deaths occur per year from pulmonary emboli, and about half occur within the first hour due to acute right heart failure.

Initially there may be few symptoms of cor pulmonale. When the disorder is advanced or acute, symptoms may include:

• Fatigue and shortness of breath on exertion
• Dizziness
• Chest pain
• Wheezing or coughing

Symptoms of heart failure may also develop:

• Edema in the legs
• Progressively worse shortness of breath

Left untreated, cor pulmonale can lead to right-heart failure and death. Anyone experiencing acute symptoms of cor pulmonale should seek medical treatment immediately.