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
The most common symptoms
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
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
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.
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:
You are also at higher risk for blood clots if you are an
older adult (especially older than 70) or extremely overweight (obese).
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.
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
vena cava filter helps keep blood clots from reaching
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.
Learning about pulmonary embolism:
Living with pulmonary embolism:
Health Tools help you make wise health decisions or take action to improve your health.
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
In rare cases, pulmonary embolism may be
caused by other substances, including:
The symptoms of
pulmonary embolism may include:
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.
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
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.
Doctors will consider aggressive steps when they are
treating a large, life-threatening 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
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:
When blood does not circulate
normally, clots are more likely to develop. Reduced circulation may result
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:
Blood is more
likely to clot in veins and arteries shortly after they are injured. Injury to
a vein can be caused by:
Call 911 or other emergency services immediately if you think you have symptoms of
Call your doctor immediately if you
have symptoms of a blood clot in the leg, including:
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.
Health professionals who can diagnose pulmonary embolism include:
To prepare for your appointment, see the topic Making the Most of Your Appointment.
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
Further testing may include:
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:
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
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:
Take steps to prevent blood clots from travel, such as drinking fluids and 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 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
Measures that reduce your risk for developing
a deep vein thrombosis include the following:
For more information on how to prevent clots from
developing, see the topic
Deep Vein Thrombosis.
Medicines can help prevent repeated
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.
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.
Surgery increases the risk of
forming new blood clots that can cause another pulmonary embolism.
If surgery or medicines are not options, other methods of
pulmonary embolism may be considered, such as a vena
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
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.
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ByHealthwise StaffPrimary Medical ReviewerE. Gregory Thompson, MD - Internal MedicineMartin J. Gabica, MD - Family MedicineAdam Husney, MD - Family MedicineSpecialist Medical ReviewerJeffrey S. Ginsberg, MD - Hematology
Current as ofMarch 20, 2017
Current as of:
March 20, 2017
E. Gregory Thompson, MD - Internal Medicine & Martin J. Gabica, MD - Family Medicine & Adam Husney, MD - Family Medicine & Jeffrey S. Ginsberg, MD - Hematology
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Last modified on: 8 September 2017