Pulmonary Embolism

Pulmonary Embolism

Topic Overview

What is pulmonary embolism?

Pulmonary embolism is
the sudden blockage of a major blood vessel (artery) in the lung, usually by a
blood clot. In most cases, the clots are small and are not deadly, but they
can damage the lung. But if the clot is large and stops blood flow to the lung,
it can be deadly. Quick treatment could save your life or reduce the risk of
future problems.

What are the symptoms?

The most common symptoms

  • Sudden shortness of breath.
  • Sharp chest pain that is worse when you cough or take a deep
  • A cough that brings up pink, foamy mucus.

Pulmonary embolism can also cause more general symptoms.
For example, you may feel anxious or on edge, sweat a lot, feel lightheaded or
faint, or have a fast heart rate or

If you have symptoms like
these, you need to see a doctor right away, especially if they are sudden and

What causes pulmonary embolism?

In most cases,
pulmonary embolism is caused by a blood clot in the leg that breaks loose and
travels to the lungs. A blood clot in a vein close to the skin is not likely to
cause problems. But having blood clots in deep veins (deep vein thrombosis) can lead to pulmonary embolism. More than 300,000 people each year have deep vein thrombosis or a pulmonary embolism.footnote 1

Other things
can block an artery, such as tumors, air bubbles,
amniotic fluid, or fat that is released into the blood
vessels when a bone is broken. But these are rare.

What increases your risk of pulmonary embolism?

Anything that makes you more likely to form blood clots increases your
risk of pulmonary embolism. Some people are born with blood that clots too
quickly. Other things that can increase your risk include:

  • Being inactive for long periods. This can
    happen when you have to stay in bed after surgery or a serious illness, or when
    you sit for a long time on a flight or car trip.
  • Recent surgery
    that involved the legs, hips, belly, or brain.
  • Some diseases, such as cancer,
    heart failure,
    stroke, or a severe infection.
  • Pregnancy and childbirth (especially if you had a
    cesarean section).
  • Taking birth control
    pills or
    hormone therapy.
  • Smoking.

You are also at higher risk for blood clots if you are an
older adult (especially older than 70) or extremely overweight (obese).

How is pulmonary embolism diagnosed?

It may be
hard to diagnose pulmonary embolism, because the symptoms are like those of
many other problems, such as a
heart attack, a
panic attack, or
pneumonia. A doctor will start by doing a physical
exam and asking questions about your past health and your symptoms. This helps
the doctor decide if you are at high risk for pulmonary embolism.

Based on your risk, you might have tests to look for blood clots or rule
out other causes of your symptoms. Tests may include blood tests, a
CT angiogram, and a ventilation-perfusion lung scan.

How is it treated?

Doctors usually treat pulmonary
embolism with medicines called
anticoagulants. They are often called blood thinners,
but they don't really thin the blood. They help prevent new clots and keep
existing clots from growing.

Most people take
a blood thinner for a few months. People at high risk for blood clots may need it for
the rest of their lives.

If symptoms are severe and
life-threatening, "clot-busting" drugs called thrombolytics may be used. These
medicines can dissolve clots quickly, but they increase the risk of serious
bleeding. Another option is surgery or a minimally invasive procedure to remove the clot (embolectomy).

Some people may have a filter put
into the large vein (vena cava) that carries blood from the lower body to the
heart. A
vena cava filter helps keep blood clots from reaching
the lungs.

If you have had pulmonary embolism once, you are more
likely to have it again. Blood thinners can help reduce your risk, but they
increase your risk of bleeding. If your doctor prescribes blood thinners, be
sure you understand how to take your medicine safely.

You can reduce your risk of pulmonary
embolism by doing things that help prevent blood clots in your legs.

  • Avoid sitting for long periods. Get up and
    walk around every hour or so, or flex your feet often.
  • Get moving
    as soon as you can after surgery.
  • Wear
    compression stockings if you are at high risk.
  • If you take blood
    thinners, take them just the way your doctor tells you to.

Frequently Asked Questions

Learning about pulmonary embolism:

Being diagnosed:

Getting treatment:

Living with pulmonary embolism:

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Pulmonary embolism is caused by a blocked artery in the lungs. The most common
cause of such a blockage is a blood clot that forms in a
deep vein in the leg and travels to the lungs, where
it becomes lodged in a smaller lung artery.

Almost all blood
clots that cause pulmonary embolism are formed in the
deep leg veins. Clots also can form in the deep
veins of the arms or pelvis.

Sometimes blood clots develop in
surface veins. But these clots rarely lead to
pulmonary embolism.

In rare cases, pulmonary embolism may be
caused by other substances, including:

  • Small masses of infectious
  • Fat, which can be released into the bloodstream after
    some types of bone fractures, surgery, trauma, or severe burns.
  • Air
    bubbles or substances that get into the blood from trauma, surgery, or medical procedures.
  • Tumors caused by rapidly growing cancer cells.


The symptoms of
pulmonary embolism may include:

  • Shortness of breath that may occur
  • Sudden, sharp chest pain that may become worse with deep
    breathing or coughing.
  • Rapid heart rate.
  • Rapid
  • Sweating.
  • Anxiety.
  • Coughing up
    blood or pink, foamy mucus.
  • Fainting.
  • Heart
  • Signs of

Pulmonary embolism may be hard to diagnose because its
symptoms may occur with or are similar to other conditions, such as a
heart attack, asthma, a
panic attack, or
pneumonia. Also, some people with pulmonary embolism
don't have symptoms.

What Happens

If a large blood clot blocks
the artery in the lung, blood flow may be completely stopped, causing sudden
death. A smaller clot reduces the blood flow and may cause damage to lung
tissue. But if the clot dissolves on its own, it may not cause any major

Symptoms of
pulmonary embolism usually begin suddenly. Reduced
blood flow to one or both lungs can cause shortness of breath and a rapid heart
rate. Inflammation of the tissue covering the lungs and chest wall (pleura) can
cause sharp chest pain.

Without treatment, pulmonary embolism is
likely to come back.

Complications of pulmonary embolism

  • Cardiac arrest and sudden
  • Shock
  • Abnormal heart rhythms
  • Death of part of
    the lung, called pulmonary infarction
  • A buildup of fluid (pleural effusion) between the outside lining
    of the lungs and the inner lining of the chest cavity
  • Paradoxical embolism
  • Pulmonary hypertension

Doctors will consider aggressive steps when they are
treating a large, life-threatening pulmonary embolism.

Chronic or recurring pulmonary embolism

Blood clots that cause
pulmonary embolism may dissolve on their own. But if you have had pulmonary
embolism, you have an increased risk of a repeat episode if you do not receive
treatment. If pulmonary embolism is diagnosed promptly, treatment with
anticoagulant medicines may prevent new blood clots from forming.

The risk of having
another pulmonary embolism caused by something other than blood clots varies.
Substances that are reabsorbed into the body, such as air, fat, or amniotic
fluid, usually do not increase the risk of having another episode. Cancer
increases the risk of blood clots.

Having multiple episodes of
pulmonary embolism can severely reduce blood flow through the lungs and heart.
Over time, this increases blood pressure in the lungs (pulmonary hypertension),
eventually leading to right-sided
heart failure and possibly

What Increases Your Risk

Having a blood clot in the
deep vein of your leg and having a previous
pulmonary embolism are the two greatest risk factors
for pulmonary embolism.

For more information on risk factors for
blood clots in the legs, see the topic Deep Vein Thrombosis.

Many things increase your risk for a blood clot. These include:

  • Having slowed blood flow, abnormal
    clotting, and a blood vessel injury.
  • Age. As people get older (especially older than age 70),
    they are more likely to develop blood clots.
  • Weight. Being
    overweight increases the risk for developing clots.
  • Not taking
    anticoagulant medicine as prescribed, unless your doctor tells you to stop taking it.

Slowed blood flow

When blood does not circulate
normally, clots are more likely to develop. Reduced circulation may result

  • Long-term bed rest, such as if you are
    confined to bed after an operation, injury, or serious
  • Traveling and sitting for a long time, especially when
    traveling long distances by airplane.
  • Leg paralysis. When you use your muscles, the muscles contract,
    and that squeezes the blood vessels in and around the muscles. The squeezing
    helps the blood move back toward the heart. Paralysis can reduce circulation
    because the muscles can't contract.

Abnormal clotting

Some people have blood that
clots too easily or too quickly. People with this problem are more likely to
form larger clots that can break loose and travel to the lungs. Conditions that
may cause increased clotting include:

  • Inherited factors. Some people have an
    inherited tendency to develop blood clots that can lead to pulmonary
  • Family history of close relatives, such as a sibling, who has had deep vein thrombosis or pulmonary embolism.
  • Cancer and its treatment.
  • Blood vessel diseases, such as varicose veins, heart attack, heart failure, or a stroke.
  • Pregnancy. A woman's risk for
    developing blood clots increases both during pregnancy and shortly after
  • Using hormone therapy or birth control pills or patches.
  • Smoking.

Injury to the blood vessel wall

Blood is more
likely to clot in veins and arteries shortly after they are injured. Injury to
a vein can be caused by:

  • Recent surgery
    that involved the legs, hips, belly, or brain.
  • A tube (catheter) placed in a large vein of the body
    (central venous catheter).
  • Damage from an injury, such as a broken hip, serious burn, or serious infection.

When To Call a Doctor

Call 911 or other emergency services immediately if you think you have symptoms of
pulmonary embolism.

Symptoms include:

  • Sudden shortness of breath.
  • Sharp chest pain that sometimes becomes worse with deep breathing or coughing.
  • Coughing up blood.
  • Fainting.
  • Rapid pulse or irregular heartbeat.
  • Anxiety or sweating.

Call your doctor immediately if you
have symptoms of a blood clot in the leg, including:

  • Swelling, warmth, or tenderness in the soft
    tissues of your leg. Swelling may also appear as a swollen ridge along a blood vessel that you can feel.
  • Pain in your leg that gets worse when you
    stand or walk. This is especially important if there is also swelling or
    redness in your leg.

Blood clots in the deep veins of the leg are the most
common cause of pulmonary embolism. For more information on these types of
blood clots, see the topic Deep Vein Thrombosis.

Who to see

Health professionals who can diagnose pulmonary embolism include:

To prepare for your appointment, see the topic Making the Most of Your Appointment.

Exams and Tests

pulmonary embolism is difficult, because there are many other medical conditions, such as a
heart attack or an
anxiety attack, that can cause similar symptoms.

Diagnosis depends on an
accurate and thorough
medical history and ruling out other conditions. Your
doctor will need to know about your symptoms and
risk factors for pulmonary embolism. This information, combined
with a careful
physical exam, will point to the initial tests that
are best suited to diagnose a
deep vein thrombosis or pulmonary embolism.

Tests that are often done if you have shortness of breath or chest pain

  • A
    chest X-ray. Results may rule out an enlarged heart or
    pneumonia as a cause of your symptoms. If the chest
    X-ray is normal, you may need further testing.
  • Electrocardiogram (EKG, ECG). The electrical activity
    of the heart is recorded with this test. EKG results will help rule out a
    possible heart attack.

Further testing may include:

  • D-dimer. A D-dimer blood test measures
    a substance that is released when a blood clot breaks up. D-dimer levels are
    usually high in people with pulmonary embolism.
  • CT (computed tomography) scan or CT angiogram. These tests might be done to look for a pulmonary
    embolism or for a blood clot that may cause a pulmonary embolism.
  • Magnetic resonance imaging (MRI). This test may be
    used to view clots in the lungs.
  • Doppler ultrasound. A Doppler ultrasound test uses
    reflected sound waves to determine whether a blood clot is present in the large
    veins of the legs.
  • Echocardiogram (echo). This test detects abnormalities in the size or function of the
    heart's right ventricle, which may be a sign of pulmonary
  • Ventilation-perfusion scanning. This
    test scans for abnormal blood flow through the lungs after a radioactive tracer
    has been injected and you breathe a radioactive gas.
  • Pulmonary angiogram. This invasive test is done only in rare cases to diagnose pulmonary embolism.

After your doctor has determined that you have a pulmonary
embolism, other tests can help guide treatment and suggest how well you will
recover. These tests may include:

  • A blood test to check the level of the hormone
    brain natriuretic peptide (BNP). Higher levels of BNP
    mean your heart is under increased stress.
  • A blood test to look at
    the level of the protein
    troponin. Higher levels of troponin can mean there is
    damage to your heart muscle.

Treatment Overview

Treatment of
pulmonary embolism focuses on preventing future
pulmonary embolism by using
anticoagulant medicines. Anticoagulants prevent
existing blood clots from growing larger and help prevent new ones from

If symptoms are severe and life-threatening,
immediate and sometimes aggressive treatment is needed. Aggressive treatment
may include
thrombolytic medicines, which can dissolve a blood
clot quickly but also increase the risk of severe bleeding. Another option for
life-threatening, large pulmonary embolism is to remove the clot. This is
called an embolectomy. An embolectomy is done during a surgery or minimally invasive procedure.

Some people may also benefit from having a
vena cava filter inserted into the large central vein
of the body. This filter can help prevent blood clots from reaching the lungs.
This filter might be used if you have problems taking an anticoagulant.


Daily use of
anticoagulant medicines may help prevent recurring
pulmonary embolism by stopping new blood clots from
forming and stopping existing clots from growing.

The risk of
forming another blood clot is highest in the weeks after the first episode of
pulmonary embolism. This risk decreases over time. But the risk remains high
for months and sometimes years, depending upon what caused the pulmonary
embolism. People with recurrent blood clots and/or pulmonary embolism may have
to take anticoagulants daily for the rest of their lives. Anticoagulant medicines also are often used for people who
are not active due to illness or injury, or people who are having surgery on
the legs, hips, belly, or brain.

preventive methods may also be used, such as:

  • Getting you moving shortly after
  • Wearing
    compression stockings to help prevent leg deep vein
    thrombosis if you are at increased risk for this condition.

Take steps to prevent blood clots from travel, such as walking around every hour. Because of long periods of inactivity, you are at higher risk for blood clots when you are

If you are already at high risk for pulmonary embolism or deep vein thrombosis, talk to your doctor before taking a long flight or car trip. Ask if you need to take any special precautions to prevent blood clots during travel.

Home Treatment

Home treatment is not recommended for
initial treatment for
pulmonary embolism. But it is important for preventing
more clots from developing and causing a
deep vein thrombosis, which can lead to recurring
pulmonary embolism.

Measures that reduce your risk for developing
a deep vein thrombosis include the following:

  • Exercise. Keep blood moving in your legs by
    pointing your toes up toward your head so that your calves are stretched, then
    relaxing. Repeat. This exercise is especially important when you are sitting
    for long periods of time, for example, on long driving trips or airplane
  • Get up out of bed as soon as possible after an illness or
    surgery. It is very important to get moving as soon as you are able. If you
    cannot get out of bed, do the leg exercises described above every hour to keep
    the blood moving through your legs.
  • Quit smoking.
  • Wear
    compression stockings to help prevent leg deep vein
    thrombosis if you are at increased risk for this condition.

For more information on how to prevent clots from
developing, see the topic
Deep Vein Thrombosis.


Medicines can help prevent repeated
episodes of
pulmonary embolism by preventing new blood clots from
forming or preventing existing clots from getting larger.


Anticoagulants are prescribed when pulmonary embolism
is diagnosed or strongly suspected.

You'll likely take an anticoagulant for at least 3 months after
pulmonary embolism to reduce the risk of having another blood clot.footnote 2 Treatment
with anticoagulants may continue throughout your life if the risk of having
another pulmonary embolism remains high.

Different types of anticoagulants are used to treat pulmonary embolism. Talk with your doctor to decide which medicine is right for you.

In the hospital, you might be given an anticoagulant as a shot or through an IV. After you go home, you might give yourself shots for a few days. For the long term, you'll likely take a pill.

Anticoagulants include:

  • Apixaban.
  • Dabigatran.
  • Edoxaban.
  • Heparin.
  • Rivaroxaban.
  • Warfarin.

Safety tips for anticoagulants

If you take an anticoagulant, you can take steps to prevent bleeding. This includes preventing injuries and getting regular blood tests if needed.


Clot-dissolving (thrombolytic) medicines are not
commonly used to treat pulmonary embolism. Although they can quickly dissolve a
blood clot, thrombolytics also greatly increase the risk of serious bleeding.
They are sometimes used to treat a life-threatening pulmonary


The removal of a clot is called an
embolectomy. An embolectomy might be done during a surgery. Or it might be done with a minimally invasive procedure that uses a catheter (a thin tube that is guided through a blood vessel). This type of treatment for
pulmonary embolism is used only in rare cases. It is considered
for people who can't have other kinds of treatment or those whose clot is so
dangerous that they can't wait for medicine to work. An embolectomy also may
be an option for a person whose condition is stable but who shows signs of
significant reduced blood flow in the pulmonary artery.

What to think about

Surgery increases the risk of
forming new blood clots that can cause another pulmonary embolism.

Other Treatment

If surgery or medicines are not options, other methods of
pulmonary embolism may be considered, such as a vena
cava filter.

Other treatment choices

vena cava filter may be inserted in the large central
vein that passes through the abdomen and returns blood from the body to the
heart (vena cava). This filter can prevent blood clots in the leg or pelvic
veins from traveling to the lungs and heart. These filters may be permanent or

What to think about

Vena cava filters aren't
typically recommended as the first treatment for pulmonary embolism. But they may be used in some people. For example, they may be used if a person cannot take anticoagulant medicine.

Vena cava filters can cause serious health problems if they break or become
blocked with one or more blood clots.

Other Places To Get Help


National Heart, Lung, and Blood Institute (U.S.)

American Heart Association

American College of Cardiology: CardioSmart

Related Information



  1. U.S. Department of Health and Human Services (2008). The Surgeon General's call to action to prevent deep vein thrombosis and pulmonary embolism. Available online: http://www.surgeongeneral.gov/library/calls/deepvein/index.html.
  2. Guyatt GH, et al. (2012). Executive summary: Antithrombotic therapy and prevention of thrombosis, 9th ed.—American College of Chest Physicians evidence-based clinical practice guidelines. Chest, 141(2, Suppl): 7S–47S.

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ByHealthwise StaffPrimary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine Martin J. Gabica, MD - Family Medicine Adam Husney, MD - Family Medicine Specialist Medical Reviewer Jeffrey S. Ginsberg, MD - Hematology

Current as ofFebruary 23, 2018

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