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Pulmonary Embolism (PE)


The Manual's Editorial Staff

Reviewed/Revised May 2023
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What is pulmonary embolism?

A pulmonary embolism is a clump of material (usually a blood clot) that gets stuck while moving through your bloodstream and blocks a blood vessel in your lungs.

  • A pulmonary embolism blocks a blood vessel in your lungs, which makes it hard for blood to pass through your lungs and get oxygen

  • A small pulmonary embolism may not be dangerous but the bigger the embolism, the more harm it causes

  • The most common symptom is trouble breathing

  • A big pulmonary embolism can cause death right away

  • Doctors treat pulmonary embolism with blood thinners for a few months

  • If you keep having pulmonary embolisms, you may need to take blood thinners for the rest of your life

What causes pulmonary embolism?

A pulmonary embolism is usually caused by a blood clot. Not all blood clots cause harm. For example, blood clots are needed to stop the bleeding in a cut. However, blood clots can form inside blood vessels when they aren’t needed, as in deep vein thrombosis Deep Vein Thrombosis (DVT) Deep vein thrombosis (DVT) is when a blood clot forms inside a large vein. Usually the vein is deep in your leg, but a clot may form in a vein in your pelvic area or your arm. A blood clot is... read more . Most often, these unnecessary blood clots form in big veins deep inside your legs. These clots can break off and travel to your lungs or your heart.

Certain conditions increase your chance of having a pulmonary embolism including:

  • Older age (usually over 60)

  • Previous blood clots

  • Cancer

  • A broken leg or hip

  • Pregnancy

  • Major surgery within the past 3 months

  • Smoking

  • Taking the hormone estrogen or medicines similar to it

In general, you're more likely to get blood clots in your legs when you can't move your legs much. You might not move much if you break a leg. Also, when you have surgery or a long illness, you may have to lay in bed for awhile. Even taking a long plane flight can be a risk because it can keep you from moving your legs enough.

Sometimes other substances can cause a pulmonary embolism. These include:

  • Fat released from broken bones or during surgery on bones (orthopedic surgery)

  • Fluid that surrounds a baby in the womb (amniotic fluid) released into your blood during a difficult delivery

  • Air bubbles from underwater diving

  • Foreign material mixed in with illegal drugs that are injected

What are the symptoms of pulmonary embolism?

A small pulmonary embolism might not cause any symptoms. If you do have symptoms, they often include:

  • Shortness of breath

  • Chest pain

  • Light-headedness or fainting

If the pulmonary embolism came from a blood clot in your leg, that leg may be swollen and painful. Sometimes you might not have any symptoms in your leg.

Pulmonary Embolism

How can doctors tell if I have pulmonary embolism?

Pulmonary embolism can be hard for doctors to recognize. Your doctor will ask about your symptoms and what risk factors you have.

Because the symptoms of pulmonary embolism can be like those of other types of heart and lung disorders, doctors usually start with general tests such as:

If your symptoms or test results suggest you might have a pulmonary embolism, your doctor may:

Less often, your doctor may do a lung scan Radionuclide Scanning Radionuclide scanning is a type of medical imaging that produces images by detecting radiation after a radioactive material is administered. During a radionuclide scan, a small amount of a radionuclide... read more . In a lung scan, the doctor injects a small amount of radioactive liquid in your vein. Then the doctor takes pictures of your chest with a camera that detects radiation. The lung scan can show whether blood is flowing to all parts of your lungs.

How do doctors treat pulmonary embolism?

Doctors use different treatments depending on how severe the embolism is.

You will:

  • Be cared for in the hospital

  • Get blood thinning medicines (anticoagulants) to prevent more clots from forming

The blood thinner may be given by mouth, directly into your vein (IV), or by shots under your skin. When you go home, you'll take a blood thinner for a few months. If you have serious risk factors or have had several pulmonary embolisms, you may need to take the blood thinner for your whole life.

If you have a large, dangerous clot in your lungs that could be fatal, doctors may:

  • Give clot-busting medicine IV to dissolve the clot

  • Rarely, try to remove the clot using a special IV catheter or doing surgery

If you can't take blood thinners or you keep having clots despite blood thinners, doctors may:

  • Put a wire mesh filter in the big vein in your abdomen to keep clots in your legs from getting to the lungs

Inferior Vena Cava Filters: One Way to Prevent Pulmonary Embolism

To prevent pulmonary embolism, doctors usually use medicines that limit blood clotting. However, for some people, doctors may recommend that a filter (formerly called an umbrella) be temporarily or permanently placed in the inferior vena cava. This filter device typically is recommended when medicines can't be used, for example, when a person is also having bleeding. The filter can trap emboli before they reach the heart but allow blood to flow through freely. Emboli that are trapped sometimes dissolve on their own.

Inferior Vena Cava Filters: One Way to Prevent Pulmonary Embolism

How can I prevent pulmonary embolism?

You usually need to take preventive measures if:

  • You have had pulmonary embolism or blood clots in your legs before

  • You're having certain types of surgery, particularly orthopedic surgery on your hips or legs

  • You have cancer or a disorder that makes your blood clot too much

  • You're going to be in a hospital bed for a long time without being able to get up

Doctors advise different measures depending on your circumstances. They may have you:

  • Take blood thinners for a little while right after surgery

  • Take blood thinners for a long time if you have had pulmonary embolism or blood clots before

  • Wear long, tight stockings (compression stockings) or inflatable boots that squeeze your lower leg muscles off-and-on to keep the blood moving well

  • Get out of bed and walk around as soon as possible after a surgery

You can help prevent blood clots on airplane flights by:

  • Doing leg exercises

  • Moving more—for example, standing, stretching, and walking around at least every 2 hours

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