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Pulmonary Embolism

What is a Pulmonary Embolism?

A pulmonary embolism is a blockage of an artery in the lungs. The embolism prevents blood and nourishment from getting to a specific area of the lungs. This may lead to the death of lung tissue in this area. Damage to the lungs may make it difficult for the lungs to work properly. In severe cases, a pulmonary embolism can lead to death.


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Pathway of Pulmonary Embolism

Copyright © Nucleus Medical Media, Inc.

Causes of Pulmonary Embolism

An embolism is caused by a lump of material, called an embolus, that is floating in the blood. An embolus can be a blood clot, air bubble, a piece of fat, bone marrow, or tumor tissue. The embolus travels from its original location and passes through larger blood vessels until it gets stuck in a smaller blood vessel. In this case, the embolus is trapped in an artery of the lungs.

The embolus in a pulmonary embolism is usually a blood clot. It most often starts in a vein in the legs or pelvis.

Pulmonary Embolism Risk Factors

Factors that increase your chance of developing a pulmonary embolism include:

  • Blood clot in a deep vein of a leg or the pelvis
  • Increased levels of clotting factors in the blood
  • Prolonged bed rest
  • Major surgery, especially after pelvic surgery, knee replacement, or heart surgery
  • Injury to a vein in a leg or the pelvis
  • Fractures of the hip or thigh bone
  • Certain blood disorders
  • Prolonged sitting, such as during a long trip
  • Pregnancy or postpartum period
  • Smoking
  • Obesity
  • Inflammatory bowel disease
  • Autoimmune disorder, such as immune thrombocytopenic purpura, polyarteritis nodosa, or polymyositis
  • Cancer
  • Taking certain medications, such as birth control pills or antipsychotics

Symptoms of Pulmonary Embolism

The symptoms of a pulmonary embolism vary depending on the size and location of the blockage. The area of lung affected by the lack of blood will also affect the symptoms. Pulmonary embolism may cause:

  • Shortness of breath that starts suddenly for no obvious reason
  • Chest pain, especially when breathing or coughing (it can mimic a heart attack)
  • Feeling faint or lightheaded
  • Cough, sometimes with bloody phlegm
  • Rapid heartbeat
  • Rapid breathing
  • Anxiety
  • Feeling of impending doom


Your doctor will ask about your symptoms and medical history. A physical exam will be done. Your doctor may order the following tests:

  • Arterial blood gas study — to check oxygen levels and lung function
  • EKG — to assess the electrical activity of the heart
  • D-Dimer blood test — to detect the presence of a clot
  • If you have a family history of blood clots, and had blood clots in the past for no apparent reason, your doctor may do additional blood tests. The tests will look for possible inherited defects in your clotting system, such as:
    • Factor V Leiden mutation (seen in up to 40% of cases)
    • Increased factor VIII

Imaging tests create pictures of internal structures. Imaging tests may include:

  • Chest X-ray — to look for signs of dead tissue; the pulmonary embolism cannot be seen on the chest x-ray
  • Lung perfusion scan — a test that compares breathing and circulation in all areas of the lungs
  • CT scan of the chest
  • Pulmonary angiogram —to see blood vessels in the lungs
  • Magnetic resonance (MR) angiography
  • Echocardiography —to examine the size, shape, and motion of the heart

If you are diagnosed with a pulmonary embolism, follow your doctor's instructions .

Pulmonary Embolism Treatments

Treatment depends on the size and severity of the clot. Emergency treatment and hospitalization may be needed.

Emergency treatment for shock may include IV fluids, medications, and oxygen therapy.

Treatment includes medication, and in some cases, surgery.


The first step in treatment is an anticoagulant medications (blood thinners). These may include:

  • Enoxaparin
  • Fondaparinux
  • Heparin

After the initial period, the blood thinner will be switched to a longer-acting anticoagulant. One example is warfarin .

Another type of medication may be needed to dissolve the clot. These are called thrombolytics. Examples include alteplase and urokinase. This type of medication is usually only used in patients with a pulmonary embolism that is very large or is causing severe illness. Thrombolytics will not be used if you have a high risk of bleeding.


Surgery to remove the clot may be needed if the blockage is very large, not responding to treatment, or the person is in shock. The surgery is called an embolectomy.

Clot-Trapping Filter

Some people may have repeated problems with blood clots. Others cannot take anticoagulant medications. In these cases, a surgical procedure will be done to place a filter in the main veins of the legs. The filter will trap clots before they can travel to the lungs.


Prevention of pulmonary embolism means preventing clots from forming.

You can help prevent clots with a healthy lifestyle. Suggestions include:

  • Eat a healthful diet that is low in saturated fat and rich in whole grains, fruits, and vegetables.
  • Begin a safe exercise program with the advice of your doctor.
  • Walk or move your legs to break up long periods of sitting.
  • If you smoke, talk with your doctor on ways you can quit.
  • Unless you are on a fluid-restricted diet, be sure to drink lots of water.

People at high risk of developing blood clots can do the following:

  • Take medication if your doctor recommends it. Anticoagulant drugs are most commonly used.
  • Wear elastic stockings if suggested by your doctor. They can help improve circulation in your legs.
  • Walk or move your legs to break up long periods of sitting. If you are traveling, get up and walk every few hours.


Call 434.243.3675.


Content was created using EBSCO’s Health Library. Edits to original content made by Rector and Visitors of the University of Virginia. This information is not a substitute for professional medical advice.

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