Deep vein thrombosis and pulmonary embolism, often referred together as venous thromboembolism (VTE), occur when blood clots abnormally form in large veins and travel through the bloodstream into the lungs. These are dangerous conditions that can become life-threatening—immediately seek care if you or someone you know experience symptoms of VTE.
What is deep vein thrombosis?
Deep vein thrombosis (DVT) is a condition in which a blood clot forms in the larger veins that are not near the surface of the body but underneath layers of tissue and muscle—the “deep veins”. These clots most often form in the legs but can occur in the arm or other parts of the body. They can form after long periods of rest or immobility where blood flow is slowed, such as after surgery, long-distance travel, or days of bed rest.
DVT symptoms
DVT symptoms can vary, and not everyone with a DVT will be symptomatic. However, common DVT symptoms include:
- Swelling in the affected leg
- Warm and/or discolored skin, usually red or purple
- Pain, cramping, or soreness
Many people don’t recognize they have a DVT until it breaks loose from the blood vessel walls and travels through the body. These clots often end up in the lungs, which is a pulmonary embolism.
What is pulmonary embolism?
A pulmonary embolism (PE) is a blood clot in one or both lungs. Clots are generally formed in other parts of the body, often the veins in the leg, and travel through the blood stream to the lung. The clot blocks blood flow to your lungs, which can lead to low oxygen levels in the lungs, increased blood pressure in pulmonary arteries (the arteries within the lungs), and strain on the right side of the heart.
According to the American Heart Association’s 2025 Heart Disease and Stroke Statistics report, pulmonary embolism accounted for nearly 524,000 hospitalizations in the United States in 2021. This is about 41 percent of all hospitalizations related to venous thromboembolism.
Pulmonary embolism symptoms
The most common symptoms of PE include:
- Shortness of breath or dyspnea
- Chest pain, especially pain that worsens with deep breaths, coughing, or sneezing
- Coughing or coughing up blood
- Dizziness or fainting
Some less common symptoms include arrhythmias, such as atrial fibrillation, or a condition known as hemodynamic collapse—low blood pressure, irregular heart rate, restlessness, and sometimes unresponsiveness.
These symptoms can be indicative of a variety of conditions and require prompt medical attention. Call 911 if you or someone nearby experience these symptoms.
How are PE and DVT diagnosed?
Patients who come to an emergency department with symptoms of PE or DVT have bloodwork done to test for certain markers. These markers include:
- D-dimer, a protein fragment that shows up in the blood when a blood clot dissolves
- Brain natriuretic peptide, a protein that is made by your heart and blood vessels
- Troponin, a protein that shows up in the blood because of heart muscle damage
- Arterial blood gas, measure how much oxygen and carbon dioxide are in your blood
In addition to bloodwork, patients will undergo diagnostic imaging tests, including electrocardiography (ECG), chest radiograph, or chest CT angiography.
How are pulmonary embolism or deep vein thrombosis treated?
When PE is suspected or diagnosed, the first step in treatment is blood thinners (anticoagulation), which helps to dissolve the clot and prevent more clots from forming, enlarging, or embolizing. Supportive care, including supplemental oxygen when needed, is also a typical treatment.
For the most severe PE, other therapies such as “clot busting” medication (thrombolytics), or mechanical treatments may be indicated. Thrombectomy, a direct removal of the clot in the lungs, can be performed with surgery, or with a minimally invasive, catheter procedure.
Deep vein thrombosis is similarly treated with blood thinners to help the body reduce the clot. In certain instances, some DVT may warrant treatment with thrombolytics or a catheter thrombectomy.
Long-term treatment after hospitalization typically includes oral anticoagulation to treat the initial clot and to reduce the risk of repeated blood clots. Pulmonologists, cardiologists, radiologists, cardiac surgeons, and hematologists are often involved in helping determine the best treatment plan for individuals with VTE, both in the hospital and diagnosis, and in long term follow up.
Who is most at risk for pulmonary embolism or deep vein thrombosis?
Venous thromboembolism can result when there is one or a combination of slow blood flow through veins, injury to blood vessel walls, or an increased risk in clot formation.
There are some genetic risk factors that increase the risk of blood clotting, and these can run in families. There are many things that can increase the risk of developing blood clots. These risk factors include:
- Smoking or other use of tobacco products
- Lack of movement, such as bed rest for longer than three days or very long plane or car rides
- Age
- Obesity or being overweight
- Pregnancy
- Oral contraceptives or hormone replacement therapies
- Congestive heart failure, chronic lung disease, or certain autoimmune or inflammatory diseases
- Cancer
- Injury or surgery
How can I prevent deep vein thrombosis or pulmonary embolism?
Deep vein thrombosis and pulmonary embolism cannot always be prevented, but there are steps that you can take to reduce your risk. If you have had blood clots before, you should talk with your healthcare provider about specific steps you might take to prevent recurrent blood clots.
People admitted to the hospital for other reasons, or who undergo surgeries that have a higher risk of DVT, will typically be treated with medications to help prevent blood clots.
For most people, the best way to prevent blood clots is to do things to reduce your risk. Smoking cessation is important for this and for many other health reasons. Regular exercise or physical activity reduces the risk of developing blood clots. If you have a job that mostly requires sitting for long periods of time, getting up to walk or move around often may reduce the risk of developing blood clots.
If you are traveling a long distance, particularly by plane for more than three hours, frequent movement (when deemed safe to move in flight) is reasonable. Wearing compression socks or support stockings can also help improve blood flow on longer flights and is recommended for people with an increased risk of blood clots. Consult your healthcare provider if you have specific questions about reducing your risk of blood clots.
For more tips on how moving your body can improve your heart health, visit the Brown University Health Cardiovascular Institute’s webpage on heart health and exercise.
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