It may be hard to diagnose pulmonary embolism. That's because the symptoms are like those of many other problems, such as a heart attack, panic attack, or pneumonia.

A doctor will do a physical exam and ask 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 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 other tests.
• Electrocardiogram (EKG, ECG). The electrical activity of the heart is recorded with this test. EKG results will help rule out a possible heart attack.

Other tests

• D-dimer. This 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 pulmonary embolism or for a blood clot that may cause it.
• Magnetic resonance imaging (MRI). This test may be used to view clots in the lungs.
• Doppler ultrasound. This test uses reflected sound waves to look for a blood clot in the large veins of the legs.
• Echocardiogram (echo). It finds abnormalities in the size or function of the heart's right ventricle, which may be a sign of 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. This invasive test is done only in rare cases to diagnose pulmonary embolism.