Diagnosing Pulmonary Embolism

The doctor will ask about your symptoms and medical history, and perform a physical exam. Tests may include:

• Arterial blood gas study -a blood test to identify oxygen levels and other gases that are indicators of lung function
• Chest x-ray -a test that uses radiation to take a picture of structures inside the chest. A pulmonary embolism cannot be seen on the chest x-ray. Sometimes however it is associated with the lung infarct that can be visualized.
• Lung perfusion scan-a test that uses radioactive isotopes to measure breathing and circulation in all areas of the lungs. The presence of an embolus will show as a mismatch between ventilation of the portion of the lung and its blood perfusion.
• CT scan of the chest -a type of x-ray that uses a computer to make pictures of the inside of the chest. A spiral CT is a special type of a CT scan that is able to make tri-dimensional pictures. It is also a very fast scan that can be completed in a very short period of time. It has become highly popular in diagnosing pulmonary embolism.
• Pulmonary Angiogram - x-rays taken after a dye is injected into the blood vessels in the lungs. The test shows areas of blockage in the lungs. It provides a clear picture of blood flow through the arteries but this test is associated with relatively high risks for a patient.
• Pulmonary Angiogram - x-rays taken after a dye is injected into the blood vessels in the lungs. The test shows areas of blockage in the lungs. It provides a clear picture of blood flow through the arteries but this test is associated with relatively high risks for a patient.
• Pulmonary Angiogram - x-rays taken after a dye is injected into the blood vessels in the lungs. The test shows areas of blockage in the lungs. It provides a clear picture of blood flow through the arteries but this test is associated with relatively high risks for a patient.
• MR angiography- The use of magnetic resonance angiography (MRA) for the diagnosis of PE is rather limited, however it may be more usueful in the future as the technologic advances continue.
• Electrocardiogram (ECG, EKG)-a test that records the heart's activity by measuring electrical currents through the heart muscle. In case of pulmonary embolism, tachycardia (rapid heart beat) is frequently seen as well as several rhythm patterns that can help in making the diagnosis.
• Echocardiography -is useful in about 1/3 of patients with PE.

Additional tests may be done to check blood flow or look for clots in the veins, especially in the legs.

Also, there are a few blood tests available that can help in making the diagnosis:

• D-Dimer-a clot dissolving substance. Increased levels in the blood may suggest the presence of the clot. It is unfortunately a nonspecific test and a lot of different conditions may cause (eg, recent surgery) it to be elevated.

If you have a family history of blood clots, and had a few instances of blood clots for no apparent reason, your doctor may order additional blood tests. The tests will look for possible inherited defects in your clotting system. The two most frequent genetic abnormalities that increase your risk of forming blood clots are Factor V Leiden mutation (seen in up to 40 percent of cases) and increased factor VIII.