A pulmonary embolism (PE) is a blockage in a blood vessel of the lungs. The blood vessel is an artery that brings fresh blood to the lung tissue. The PE blocks the flow of blood to an area of the lungs. Lung tissue will begin to die without blood flow. The dead tissue will make it difficult for the lungs to work properly. In severe cases, a PE can lead to death.

Pathway of Pulmonary Embolism
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An embolus is a lump that is floating in the blood. It is usually made of a blood clot. Some can also be made of an air bubble, a piece of fat, bone marrow, or tumor tissue. The embolus travels through the blood until it gets stuck in a smaller blood vessel. This is when it become an embolism. In this case, it is trapped in an artery of the lungs.

A blood clot embolus that lands in the lung often comes from the legs or pelvis.

Risk Factors

Factors that may increase your chance of PE include:


The symptoms of PE will depend on the size and location of the blockage. The amount of lung tissue that has reduced blood flow will also affect the symptoms. PE 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 )
  • Back pain
  • Feeling faint or lightheaded
  • Cough , sometimes with bloody phlegm
  • Rapid breathing and heartbeat
  • 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:

  • D-Dimer blood test—to detect the presence of a clot
  • Arterial blood gas study —to check oxygen levels and lung function
  • Electrocardiogram (EKG)—to assess the electrical activity of the heart
  • If you have a personal and family history of blood clots your doctor may do tests to look for signs of genetic conditions such as:
    • Factor V Leiden mutation
    • Increased factor VIII
  • You may also have tests for any underlying disease

Images of the lungs and heart may be taken with:


Treatment will depend on the size of the clot and how severe your symptoms are. Emergency treatment may be needed.

Emergency treatment may include:

  • IV fluids
  • Oxygen therapy
  • Medicine to dissolve and prevent clots
  • IV catheter mechanical clot disruption—tube is passed through blood vessels to the clot to break it up or remove it
  • Surgery (rare)

Medicine may be all that is needed for less severe PEs. The medicine will help to break up the clot and keep new ones from forming.


Thrombolytics are a type of medicine that can dissolve a clot. It is only used in people with a very large PE that is causing severe illness. This type of medicine can cause sudden severe bleeding. It cannot be used in people with a high risk of bleeding.

Anticoagulants (blood thinners) will make it hard for blood to form clots. They will keep the clot from getting bigger and prevent new clots from forming. The body will be able to break up the clot after some time. This option may be used for smaller PEs that are not causing major symptoms. Medicine may need to be taken long term to prevent future blood clots and PEs.


Surgery to remove the clot may be needed if one or more of the following is present:

  • The blockage is very large
  • The clot is not responding to initial treatment
  • The person is in shock

The surgery is called an embolectomy.

Clot-Trapping Filter

A filter will be placed inside a large vein in the abdomen. This filter can catch blood clots that leave the lower body. It will trap the clots before they reach the lungs.

The filter is used for people that have frequent blood clots. It may be needed for people who have not had a good response to other treatment. It may also be an option for those who cannot take blood thinners.


Lowering the risk of blood clots in the legs can decrease the risk of PE.

  • Break up long periods of sitting. Get up and walk or at least move your legs.
  • If you are traveling, get up and walk every few hours.
  • Get out of bed as soon as possible after an illness or surgery.

In addition, people at high risk of developing blood clots should:

  • Take medicine if your doctor recommends it.
  • Wear elastic stockings if suggested by your doctor. They can help improve blood flow in your legs.
  • Go to regular visits with your medical team.

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