Lung Disease & Respiratory Health Center

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

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, such as having recent surgery or having a prior history or family history of blood clots. 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 include:

• 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.
• Arterial blood gas analysis. A sudden drop in the blood oxygen level may suggest a pulmonary embolism.

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.
• Spiral (helical) computed tomography. This test is used commonly in most hospitals to check for pulmonary embolism.
• 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. A pulmonary angiogram (also called a pulmonary arteriogram) is the most accurate way to diagnose pulmonary embolism. This test is not available at some smaller hospitals and is more invasive than other testing.
• Computed tomography (CT) angiogram. A CT angiogram uses a special dye and a series of X-rays to produce pictures of blood vessels. It can be done to look for a pulmonary embolism or for a blood clot that may cause a pulmonary embolism.
• 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 embolism.
• Magnetic resonance imaging (MRI). This test may be used to view clots in the deep veins and lungs.

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.