If you are preparing to go to the hospital for a procedure or have other risk factors for VTE, talk with your doctor about a plan for preventing blood clots from forming. Doctors may suggest three ways to help prevent VTE:

• Movement. Helping your blood circulate makes it harder for clots to form. Your doctor may recommend that you move around as soon as possible after surgery and as you heal. If you cannot get up and walk, try to flex and stretch your feet to improve blood flow in your calves.
• Pressure. Gentle pressure keeps blood from pooling and clotting. Your doctor may recommend applying pressure—for example, by wearing a sleeve or boot that periodically fills with air, or by wearing graduated compression stockings.
• Medicines. Your doctor may give you anticoagulant, or blood-thinning, medicines to prevent clotting. Sometimes this preventive therapy starts before surgery. Or, you may be asked to take a blood thinner during your recovery period at home. These medicines, such as heparin, warfarin, and direct oral anticoagulants, are also used to treat VTE.

Your doctor may recommend some combination of these preventive treatments for a month or more after surgery. These approaches to prevention may also be appropriate if you are admitted to the hospital for reasons other than surgery, cannot move for an extended period, or have a condition that makes it more likely that your blood will clot.

• Diagnosis will discuss tests and procedures that your doctor may use to diagnose VTE.
• Life After will explain what your doctor may recommend to prevent your VTE from recurring, getting worse, or causing complications.
• Research for Your Health will discuss how we are using current research and advancing research to prevent VTE.
• Participate in NHLBI Clinical Trials will explain our ongoing clinical studies that are investigating prevention strategies for VTE.

Deep vein thrombosis may cause the following to occur around the area of a blood clot:

• Swelling
• Pain or tenderness
• Increased warmth, cramps, or aching in the area that is swollen or painful, usually the calf or thigh
• Red or discolored skin

Signs and symptoms of pulmonary embolism include:

• Shortness of breath
• Pain with deep breathing
• Rapid breathing
• Increased heart rate

Less common signs and symptoms of pulmonary embolism may include coughing, with or without blood; feelings of anxiety or dread; light-headedness or fainting; and sweating.

Contact your doctor right away if you suspect that you have signs or symptoms of VTE. Deep vein thrombosis should be taken seriously, as it may lead to pulmonary embolism.

• Diagnosis will discuss tests and procedures used to detect signs of blood clots and blockage and help rule out other conditions that may mimic VTE.
• Treatment will explain treatment-related complications or side effects of VTE, such as bleeding.

Your doctor will ask you about your risk factors and your signs and symptoms for VTE. Your doctor may examine your heart rate and the area that is affected and ask about your overall health, including:

• Your recent medical history, especially any paralysis or periods of immobilization
• Medicines you are taking
• Recent surgeries or injuries you have had
• Whether you have been treated for cancer

• D-dimer test to measure a substance in the blood that is released when the fibrin proteins in a blood clot dissolve. If the test shows high levels of the substance, you may have VTE. If your test results are normal and you have few risk factors, you likely do not have VTE.
• Ultrasound to look for deep vein blood clots. 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 if they compress normally or if they are stiff with blood clots.
• Computed tomography (CT) angiography external link to take pictures of your blood vessels and look for blood clots in the lungs and legs. This is the most common diagnostic test for pulmonary embolism.
• Pulmonary angiography external link to confirm a pulmonary embolism if, after other testing, your doctor suspects you might have one. This test requires inserting a tube into your blood vessel. It also uses X-rays to create video of the blood flow to your lung so your doctor can identify any blood clots.
• Other imaging tests to look at blood flow through your veins, heart function, and lung function if the results of previous tests could not diagnose or rule out VTE. These include venography external link , echocardiography, ventilation/perfusion scanning, and magnetic resonance imaging (MRI).

To help diagnose VTE, your doctor may need to do tests to find out if other medical conditions are causing your symptoms. Other tests include:

• Blood tests to check whether you have an inherited blood clotting disorder if you have had repeated blood clots that are not related to another cause. Blood clots in an unusual location, such as the liver, kidney, or brain, may also suggest an inherited clotting disorder. Blood tests can also measure the level of oxygen and other gases in your blood.
• Chest X-ray to give your doctor information about what may be causing your symptoms, such as pneumonia or fluid in the lungs. A chest X-ray does not show whether you have a pulmonary embolism.
• Electrocardiogram (ECG) to identify other conditions that are causing signs of pulmonary embolism. An ECG records the electrical activity of your heart.

• Return to Risk Factors to review family history, lifestyle, or other environmental factors that increase your risk of developing clots.
• Return to Signs, Symptoms, and Complications to review common signs and symptoms of VTE.
• Return to Screening and Prevention to review what you can do to prevent clots from forming.

Anticoagulants, or blood thinners, and thrombolytics are medicines commonly used to treat VTE.

• Anticoagulants, or blood thinners, keep blood clots from getting larger and stop new clots from forming. Conventional blood thinners include warfarin and heparin, but newer blood-thinning medicines are also available. To take them, you might get an injection, take a pill, or have an IV tube inserted. Possible side effects include bleeding, especially if you are taking other medicines that also thin your blood, such as aspirin.
• Thrombin inhibitors interfere with the process of clot formation. They may be used for people who cannot take heparin.
• Thrombolytics may be used to dissolve large blood clots that cause severe symptoms or other serious complications. Because thrombolytics can cause sudden bleeding, they are used only for serious and potentially life-threatening VTE events, such as pulmonary embolism.

In some cases, including emergencies, a doctor may need to do a catheter-assisted thrombus removal. This procedure uses a flexible tube to reach a blood clot in your lung. The doctor can insert a tool in the tube to break up the clot or to deliver medicine through the tube. Usually you will get medicine to put you to sleep for this procedure.

Some people who cannot take blood thinners may need a vena cava filter to treat their deep vein thrombosis. The filter is inserted inside a large vein called the vena cava. The filter catches blood clots before they travel to the lungs, which prevents pulmonary embolism. However, the filter does not stop new blood clots from forming. A filter is not usually recommended if you have taken blood thinners.

• Life After will discuss what your doctor may recommend, including lifelong lifestyle changes and medical care to prevent your condition from recurring, getting worse, or causing complications.
• Research for Your Health will explain how we are using current research and advancing research to treat people who have VTE.
• Participate in NHLBI Clinical Trials features ongoing clinical studies that are investigating treatments for VTE.

Follow your doctor’s instructions and schedule regular appointments.

• Tell your doctor if symptoms such as pain or swelling continue. Your doctor may prescribe graduated compression stockings to give you relief.
• Take all medicines as prescribed. You will probably keep taking medicines to treat VTE for three months or longer. The most common side effect of blood thinners is bleeding. This side effect can be life-threatening.
• Check your legs for any signs or symptoms of deep vein clotting, such as swollen areas, pain or tenderness, increased warmth in swollen or painful areas, or red or discolored skin. If you think you may have another deep vein clot or are having symptoms of pulmonary embolism, contact your doctor right away.
• Tell your doctor if you notice that you bruise easily; have unexpected bleeding, such as when you floss or go to the toilet; or have unusually heavy menstrual periods.

To monitor your condition, your doctor may recommend the following tests:

• Blood tests to monitor the proper dose of medicine so that adjustments can be made as necessary. If you are taking warfarin to treat VTE, you will need to take regular tests that show how long it takes for your blood to clot. Usually, you do these tests at the doctor’s office or at a clinic. The FDA has approved several devices for self-testing external link . Your doctor may also run regular blood tests to check your kidneys or liver if you have been taking other blood-thinning medicines for more than a year. This will help your doctor make sure your body can still tolerate the medicine well.
• Ultrasounds to monitor your blood clot. These tests will help your doctor see if your blood clot has gotten bigger or has moved.

When you return home, your doctor may recommend healthy lifestyle changes to help improve your recovery.

• Heart-healthy eating. Heart-healthy eating includes limiting the amount of alcohol you drink. Alcohol can also be dangerous if you are taking blood-thinning medicine. If you are taking warfarin, talk with your doctor about your eating patterns and any supplements you take. Foods that contain vitamin K can affect how well warfarin works, so it is important to eat about the same amount of vitamin K each day. Vitamin K is found in green leafy vegetables and some oils, such as canola and soybean oils.
• Being physically active. It is important to keep moving regularly while you are healing. Ask your medical care team when you can start being physically active and how much activity is appropriate.
• Aiming for a healthy weight. If you are overweight or have obesity, you can improve your health by aiming for a healthy weight. Obesity is a risk factor for a repeat VTE event.
• Managing stress. Stress can increase the risk of other conditions that can lead to VTE, such as heart attack and stroke.
• Quitting smoking. Smoking also increases the risk of heart attack and stroke, and it may aggravate other factors known to raise the risk of VTE. Visit Smoking and Your Heart and the National Heart, Lung, and Blood Institute’s Your Guide to a Healthy Heart. For free help quitting smoking, you may call the National Cancer Institute’s Smoking Quitline at 1-877-44U-QUIT (1-877-448-7848).

Nearly one in three patients who have had VTE will experience a repeat VTE event in the next 10 years. It can take a year or more for clots to break up or stabilize and for blood flow to return to normal. If you were previously treated with blood thinners and experience a repeat VTE event, your doctor may recommend changing your medicine dose or switching you to a different type of blood thinner.

To prevent a repeat VTE event:

• See your doctor for regular checkups and follow-up tests and treatment.
• Talk to your doctor about your risk for a repeat VTE event. The risk of a repeat VTE is higher for African Americans and Hispanic Americans than it is for white Americans. It is also higher for men than for women.
• Take all medicines as your doctor prescribes. A repeat event while you are taking medicines is rare, but if it does occur, your doctor may switch your medicine or increase the dose.
• If you stop taking blood-thinning medicines, your doctor may suggest that you take aspirin to reduce the risk of getting another clot.

Medicines used to treat VTE can thin your blood too much or impair your body’s ability to clot after a wound. If you take a dose of blood-thinning medicine that is too high, it may cause bleeding in the digestive system or in the brain. These side effects can be life threatening.

Signs and symptoms of bleeding in the digestive system include:

• Bright red vomit or vomit that looks like coffee grounds
• Bright red blood in your stool or black, tarry stools
• Pain in your abdomen

Signs and symptoms of bleeding in the brain include:

• Severe pain in your head
• Sudden changes in your vision
• Sudden inability to move your legs or arms
• Memory loss or confusion

A lot of bleeding after a fall or injury, or easy bruising or bleeding, may mean that your blood is too thin. Excessive bleeding is bleeding that will not stop after you apply pressure to a wound for 10 minutes. Call your doctor right away if you have any of these signs. If you have severe bleeding, call 9-1-1.

Learn about the following ways the NHLBI continues to translate current research into improved health for people who have VTE. Research on this topic is part of the NHLBI’s broader commitment to advancing scientific discoveries in blood disorders and blood safety.

• Surgeon General’s Call to Action to Prevent Deep Vein Thrombosis and Pulmonary Embolism. With the Surgeon General’s office, the NHLBI drafted a call to action summarizing research on VTE and focusing the attention of stakeholders and the public on the importance of saving lives and reducing the burden of VTE.
• Advances in VTE diagnosis. Clinical trials led by the NHLBI have led to important advances in clinical care. The Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) study, originally launched in the 1980s, has tested the accuracy of several technologies used to diagnose pulmonary embolism. Based on the findings of the second phase of this study, investigators issued recommendations. PIOPED research continues, with the aim of finding safer and less expensive approaches to reliably assess patients.
• Enhancing the translation of research discoveries into improved prevention and treatment of VTE. The NHLBI funds cooperative agreements for research centers to participate in the Translational Research Centers in Thrombotic and Hemostatic Disorders (TRC-THD) program. The individual centers address important clinical questions through research and collaboration with other centers to improve diagnostic tools and treatments for patients who have VTE.
• Enabling progress in thrombosis research and clinical care through trans-NHLBI and trans-NIH working groups. We regularly convene working groups of experts to discuss where there are gaps in our understanding of VTE. The NHLBI helps identify areas where doctors need more evidence to help make decisions about patients in their care and funds studies to help find the answers. We have organized research meetings around thrombosis in people who have congenital heart disease or cancer, as well as meetings on pulmonary embolism complications such as pulmonary hypertension, how to tailor antithrombotic treatments, and the risk of clotting with heart pumps known as ventricular assist devices.

Learn about some of the pioneering research contributions we have made over the years that have improved clinical care.

In support of our mission, we are committed to advancing VTE research in the following ways.

• We perform research. Our Division of Intramural Research includes some of the investigators at NHLBI who are actively engaged in research on VTE.
• We fund research. Our Division of Blood Diseases and Resources (DBDR) and Division of Lung Diseases (DLD) fund research on VTE. DBDR-supported research improves our understanding of normal and abnormal blood, blood clotting, and blood flow. It also supports scientific advances in biomarkers to diagnose blood conditions and in therapeutics to treat them. The DLD funds research on the causes, diagnosis, prevention, and treatment of lung diseases. Its Lung Vascular Biology Program supports research on pulmonary embolism, including understanding how the condition develops. Search the NIH RePORTer to learn about research the NHLBI is funding on VTE.
• We stimulate high-impact research. Our Trans-Omics for Precision Medicine (TOPMed) program includes participants with pulmonary embolism and deep vein thrombosis, which may help us understand how genes contribute to differences in disease severity and how patients respond to treatment. The NHLBI Strategic Vision highlights ways we may support research over the next decade.

Learn about exciting research areas the NHLBI is exploring about VTE.