Conditions & Treatments

Pulmonary Embolism

A pulmonary embolism (PE) is a blood clot that develops in a blood vessel elsewhere in the body (most commonly from the leg), travels to an artery in the lung, and forms an occlusion (blockage) of the artery.

Pulmonary Embolism

When a blood clot forms in a blood vessel somewhere in the body, part of it can break off and travel to the lungs causing a pulmonary embolism (PE). This can cut off the flow of blood. PE is a medical emergency and may cause death. 

Often, the blood clot is 1 that formed in a deep vein of the leg. This is called deep vein thrombosis (DVT).

Health care providers use the term venous thromboembolism (VTE) to describe both PE and DVT. They use the term VTE because the 2 conditions are very closely related. And, because their prevention and treatment is are also closely related. 

What causes a pulmonary embolism?

Human torso showing heart, lungs, and major veins. Blood clot is in leg vein with arrow showing it traveling up vein to lung causing pulmonary embolism.
A pulmonary embolism is a part of a blood clot that travels to the lungs.

The most common cause of a pulmonary embolism is a blood clot (thrombus) in a large leg vein of the leg that breaks off and travels to the lungs (embolus).

An embolus may be from clots in other parts of the body. Or they may be made up of other solids, liquids, or gases that travel to the lungs. For example, 1 may be made up of fat or air bubbles.

What are the risk factors for pulmonary embolism?

The following may increase your chance of pulmonary embolism:

  • Blood clotting disorder

  • Surgery

  • Injury

  • Not moving for long periods of time, like being hospitalized, flying or riding long distances, or paralysis

  • Previous blood clots

  • Age over 60 years

  • Cancer and cancer therapy

  • Certain medical conditions, like heart failure, chronic obstructive pulmonary disease (COPD), high blood pressure, and inflammatory bowel disease, like ulcerative colitis or Crohn's disease 

  • Certain medicines, like birth control pills  or hormone replacement therapy (estrogen)

  • Pregnancy

  • Obesity

  • Other vein conditions

  • Cigarette smoking

What are the symptoms of a pulmonary embolism?

The following are the most common symptoms of a blood clot in the lungs:

  • Trouble breathing

  • Chest pain

  • Fainting

  • Fast heartbeat (palpitations)

  • Coughing (may cough up blood)

  • Sweating

If you have the symptoms that may mean a blood clot in your lungs, call 911 or get emergency help.

Symptoms of a blood clot include pain, redness, or swelling in the leg, arm, or other area. If you have these symptoms, call your health care provider.

The symptoms of a pulmonary embolism may look like other medical conditions. Always see your health care provider for a diagnosis. 

How is pulmonary embolism diagnosed?

A blood clot in the lungs is often difficult to diagnose. It may look like other conditions and diseases. Your health care provider will do a complete medical history and physical exam. Other tests may include:

  • Chest X-ray. Images are taken to check the lungs, as well as the heart. 

  • Ventilation-perfusion scan (V/Q scan). A tiny amount of radioactive material is used to check the lungs. The test checks the movement of air and the blood flow in the lungs.

  • Pulmonary angiogram. Dye (contrast) is injected to make highlight the blood vessels in the lungs.

  • Computed tomography (also called CT or CAT scan). X-rays and computer technology are used to produce detailed images of the lungs. CT with contrast may also be done.

  • Magnetic resonance imaging (MRI). Large magnets, radiofrequencies, and computer-produced, detailed images of organs and structures within the body.

  • Duplex ultrasound (US). A type of ultrasound procedure done to check the blood flow in blood vessels. 

  • Blood  tests. To check the blood's clotting status. This may include a test called D-dimer level. Other blood tests may include checking for inherited (genetic) disorders that affect blood clotting. Arterial blood gases to check the amount of oxygen in the blood may also be done.

  • Electrocardiogram (ECG or EKG). A simple procedure used to evaluate the heart. Abnormalities can be seen with acute pulmonary embolism.

Treatment of pulmonary embolism

Specific treatment will be determined by your health care provider based on:

  • How old you are

  • Your overall health and medical history

  • How sick you are

  • How well you can handle specific medicines, procedures, or therapies

  • How long the condition is expected to last

  • Your opinion or preference

Treatment for a blood clot in the lungs includes:

  • Blood thinners (anticoagulants). These medicines decrease the ability of the blood to clot. Examples include warfarin and heparin. Other anticoagulants may also be used, including rivaroxaban, apixaban, dabigatran and enoxaparin.

  • Clot busters  (thrombolytic therapy). These medicines can be delivered through a catheter, or given intravenously (IV) to break up the clot.

  • Percutaneous thrombectomy. In this procedure, a catheter is inserted to remove the clot

  • Inferior vena cava filter. In this procedure, a small filter is placed in the vena cava. This is the large blood vessel that returns blood from the body to the heart. The filter helps to prevent clots from traveling to the heart and lungs. These filters may be used if you can’t take anticoagulants or if you develop more clots even with treatment.

  • Surgical embolectomy. This is surgery to remove a blood clot in the lungs. This procedure is not often done.

Prevention of pulmonary embolism

An effective way to prevent a blood clot in the lungs is to prevent blood clots from forming in other parts of the body. This is especially important during hospitalization. Methods include:

  • Medicine. Anticoagulants and/or aspirin are often given to prevent blood clots.

  • Compression stockings. Elastic stockings that help keep blood flowing.

  • Sequential compression device (SCD) or intermittent pneumatic compression (IPC). Sleeves are placed around the legs. They are attached to a devise that also helps keep blood flowing with gentle pressure. Remove the sleeves so that you do not trip or fall when you are walking, like when you use the bathroom or shower. If you need help removing the sleeves, ask the nurse or aid. 

  • Walking. Getting up and moving as soon as possible after surgery or illness.

Avoid sitting, standing, or lying down for long periods without moving your legs and feet:

  • When traveling by car, make frequent stops to get out and move around.

  • On long airplane, train, or bus rides, get up and move around when possible.

  • If you can’t get up, wiggle your toes and tighten your calves to keep your blood moving.

Take good care of your heart and blood vessels:

  • If you smoke, you should stop. Talk with your health care provider about ways to quit.

  • Be active. Try to get 30 minutes of exercise on most days. If you are not exercising, talk with your health care provider about getting started.

  • Keep a healthy weight. If you are overweight, talk with your health care provider about improving your diet, increasing your activity level, and other ways to lose weight. 

Treatment and prevention of DVT will probably continue after you leave the hospital. It is important to follow all instructions from your health care providers during and after your time in the hospital.

When to seek medical advice

If you have symptoms that may mean a blood clot in your leg, arm, or another area, call your health care provider. And, call your health care provider if you have signs or symptoms of bleeding. For example, you may have blood in your urine, bleeding with bowel movements, nose bleeds, bleeding gums, a cut that will not stop bleeding, or bleeding from your vagina.

Call 911

If you have symptoms that may mean a blood clot in your lungs, call 911. Also, call 911 if you have heavy or uncontrolled bleeding. There is an increased risk of bleeding while taking blood thinners.

Treatment Programs

Massachusetts General Hospital understands that a variety of factors influence patients' health care decisions. That's just one reason why we're dedicated to ensuring patients understand their diagnosis and treatment options. Because a single option might not serve all patients, we offer a wide range of coordinated treatments and related services across the hospital. Patients should consult with their primary care doctor or other qualified health care provider for medical advice and diagnosis information.

Select a treatment program for more information:


  • Adult Medicine Imaging
    The Adult Medicine Imaging Program at Massachusetts General Hospital Imaging offers a wide range of diagnostic exams and minimally invasive, image-guided treatments, all provided using leading-edge equipment and interpreted by specialty-trained radiologists.
  • Pediatric Imaging
    The Pediatric Imaging Program at Massachusetts General Hospital Imaging specializes in ensuring the safety and comfort of child patients while providing the latest technology and the expertise of specialized pediatric radiologists.
  • Heart Imaging
    The Heart Imaging Program at Massachusetts General Hospital Imaging provides comprehensive diagnostic cardiac imaging, using state-of-the-art CT and MRI technology and with expert interpretation by specialty-trained cardiovascular radiologists.
  • Vascular Imaging and Intervention
    Working as part of the Fireman Vascular Center, the interventional vascular specialists of the Vascular Imaging and Intervention Program at Massachusetts General Hospital Imaging perform minimally invasive, image-guided treatments for conditions including stroke and peripheral vascular disease. In addition, our specialty-trained radiologists use the latest imaging technologies to provide diagnostic exams for a full range of vascular conditions.
MassGeneral Hospital for Children

  • Hemophilia and Thrombosis Center
    The Hemophilia and Thrombosis Center at MassGeneral Hospital for Children offers comprehensive evaluations and individualized care to children and adults with bleeding disorders due to hemophilia A, hemophilia B, rare clotting factor deficiencies and von Willebrand disease.
Transplant Center

  • Lung Transplant Program
    The Lung Transplant Program at the Massachusetts General Hospital Transplant Center brings together state-of-the-art technology and leading-edge medical and surgical interventions to provide patients with individualized care before and after their lung transplants.
Vascular Center

  • Venous Disease Treatment Program
    Physicians at the Venous Disease Program at the Massachusetts General Hospital Fireman Vascular Center use novel endovenous minimally invasive and endovascular surgical interventions, as well as lifestyle modification strategies to diagnose and treat patients with deep vein thrombosis (DVT), varicose veins and other venous disorders.
Pulmonary and Critical Care Medicine

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The MGH recently hosted a scientific symposium, “Pulmonary Embolism: What Is Known, What We Need To Know” to discuss improvements in PE detection, care coordination and patient management.

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