A pulmonary embolism can be difficult to diagnose, especially if you have underlying heart or lung disease. For that reason, your health care provider will likely discuss your medical history, do a physical exam, and order tests that may include one or more of the following.

Blood tests

Your health care provider may order a blood test for the clot-dissolving substance D dimer. High levels may suggest an increased likelihood of blood clots, although many other factors can cause high D dimer levels.

Blood tests also can measure the amount of oxygen and carbon dioxide in your blood. A clot in a blood vessel in your lungs may lower the level of oxygen in your blood.

In addition, blood tests may be done to determine whether you have an inherited clotting disorder.

Chest X-ray

This noninvasive test shows images of your heart and lungs on film. Although X-rays can't diagnose a pulmonary embolism and may even appear fine when a pulmonary embolism exists, they can rule out other conditions with similar symptoms.


A noninvasive test known as duplex ultrasonography, sometimes called a duplex scan or compression ultrasonography, uses sound waves to scan veins to check for deep vein blood clots. This test can look at veins in the thigh, knee and calf, and sometimes the arms.

A wand-shaped device called a transducer is moved over the skin, directing the sound waves to the veins being tested. These waves are then reflected back to the transducer to create a moving image on a computer. The absence of clots reduces the likelihood of deep vein thrombosis. If clots are present, treatment likely will be started immediately.

CT pulmonary angiography

CT scanning generates X-rays to produce cross-sectional images of your body. CT pulmonary angiography — also called a CT pulmonary embolism study — creates 3D images that can find changes such as a pulmonary embolism within the arteries in your lungs. In some cases, contrast material is given through a vein in the hand or arm during the CT scan to outline the pulmonary arteries.

Ventilation-perfusion (V/Q) scan

When there is a need to avoid radiation exposure or contrast from a CT scan due to a medical condition, a V/Q scan may be done. In this test, a small amount of a radioactive substance called a tracer is injected into a vein in your arm. The tracer maps blood flow, called perfusion, and compares it with the airflow to your lungs, called ventilation. This test can be used to see if blood clots are causing symptoms of pulmonary hypertension.

Pulmonary angiogram

This test provides a clear picture of the blood flow in the arteries of your lungs. It's the most accurate way to diagnose a pulmonary embolism. But because it requires a high degree of skill to perform and has potentially serious risks, it's usually done when other tests fail to provide a definite diagnosis.

In a pulmonary angiogram, a thin, flexible tube called a catheter is inserted into a large vein — usually in your groin — and threaded through your heart and into the pulmonary arteries. A special dye is then injected into the catheter. X-rays are taken as the dye travels along the arteries in your lungs.

In some people, this procedure may cause a temporary change in heart rhythm. In addition, the dye may cause increased risk of kidney damage in people with reduced kidney function.


MRI is a medical imaging technique that uses a magnetic field and computer-generated radio waves to create detailed images of the organs and tissues in your body. MRI is usually only done in those who are pregnant — to avoid radiation to the baby — and in people whose kidneys may be harmed by dyes used in other tests.

More Information


Treatment of a pulmonary embolism focuses on keeping the blood clot from getting bigger and preventing new clots from forming. Prompt treatment is essential to prevent serious complications or death.

Treatment can include medicines, surgery and other procedures, and ongoing care.


Medicines include different types of blood thinners and clot dissolvers.

  • Blood thinners. These blood-thinning medicines called anticoagulants prevent existing clots from getting bigger and new clots from forming while your body works to break up the clots. Heparin is a frequently used anticoagulant that can be given through a vein or injected under the skin. It acts quickly and is often given along with an oral anticoagulant, such as warfarin (Jantovin), until the oral medicine becomes effective. This can take several days.

    Newer oral anticoagulants work more quickly and have fewer interactions with other medicines. Some have the advantage of being given by mouth until they're effective, without the need for heparin. However, all anticoagulants have side effects, and bleeding is the most common.

  • Clot dissolvers. While clots usually dissolve on their own, sometimes thrombolytics — medicines that dissolve clots — given through a vein can dissolve clots quickly. Because these clot-busting medicines can cause sudden and severe bleeding, they usually are reserved for life-threatening situations.

Surgical and other procedures

  • Clot removal. If you have a large, life-threatening clot in your lung, your health care provider may remove it using a thin, flexible catheter threaded through your blood vessels.
  • Vein filter. A catheter also can be used to position a filter in the body's main vein, the inferior vena cava, that leads from your legs to the right side of your heart. The filter can help keep clots from going to your lungs. This procedure is usually only used for people who can't take anticoagulant drugs or those who get blood clots even with the use of anticoagulants. Some filters can be removed when no longer needed.

Ongoing care

Because you may be at risk of another deep vein thrombosis or pulmonary embolism, it's important to continue treatment, such as remaining on anticoagulants and being monitored as often as suggested by your health care provider. Also, keep regular visits with your provider to prevent or treat complications.

Clinical trials

Explore Mayo Clinic studies testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this condition.

Preparing for your appointment

A pulmonary embolism is often first evaluated in a hospital, emergency room or urgent care center. If you think you might have a pulmonary embolism, seek medical attention right away.

What you can do

You may want to prepare a list that includes:

  • A detailed description of your symptoms
  • Information about your past medical problems, especially any recent surgeries, injuries or illnesses that kept you in bed for several days
  • Details on any recent trips that involved long car or plane rides
  • All medicines you're taking, including vitamins, herbal products and any other supplements, and the doses
  • Information about the medical problems of parents or siblings
  • Questions you want to ask your health care provider

What to expect from your doctor

During the physical exam, your health care provider will likely examine your legs for evidence of a deep vein clot — an area that's swollen, tender, red and warm. Your provider will also listen to your heart and lungs, check your blood pressure and likely order one or more tests.

Dec. 01, 2022

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