How Is Pulmonary Embolism Diagnosed?

Your doctor will diagnose pulmonary embolism (PE) based on your medical history, a physical exam, and the results from tests.

Specialists Involved

Doctors who treat patients in the emergency room often are the ones to diagnose PE with the help of a radiologist. A radiologist is a doctor who deals with x rays and other similar tests.

Medical History and Physical Exam

To diagnose PE, your doctor will ask about your medical history and perform a physical exam to:

• Identify your risk factors for deep vein thrombosis (DVT) and PE
• See how likely it is that you could have PE
• Rule out other possible causes for your symptoms

During the physical exam, the doctor will check your legs for signs of DVT. He or she also will check your blood pressure and your heart and lungs.

Diagnostic Tests

A number of tests can help diagnose PE. Which tests you have will depend on how you feel when you get to the hospital, your risk factors for PE, available testing options, and other conditions you possibly have. You may have one or more of the following tests.

Ultrasound

Doctors use ultrasound to look for blood clots in your legs. Ultrasound uses high-frequency sound waves to check the flow of blood in your veins.

Gel is put on the skin of your leg. A hand-held device called a transducer is placed on the leg and moved back and forth over the affected area. The transducer gives off ultrasound waves and detects their echoes after they bounce off the vein walls and blood cells.

A computer then turns the echoes into a picture on a computer screen, allowing your doctor to see the blood flow in your leg. If blood clots are found in the deep veins of your legs, your doctor will recommend treatment.

DVT and PE are both treated with the same medicines.

Computed Tomography Scans

Doctors use computed tomography (to-MOG-rah-fee), or CT, scans to look for blood clots in your lungs and in your legs.

Dye is injected into a vein in your arm. The dye makes the blood vessels in your lungs and legs show up on an x-ray image. While you lie on a table, an x-ray tube rotates around you, taking pictures from different angles.

This test allows doctors to detect most cases of PE. The test only takes a few minutes. Results are available shortly after the scan is completed.

Lung Ventilation/Perfusion Scan

A lung ventilation/perfusion scan, or VQ scan, uses a radioactive substance to show how well oxygen and blood are flowing to all areas of the lungs. This test can help detect PE.

Pulmonary Angiography

Pulmonary angiography (an-jee-OG-ra-fee) is another test used to diagnose PE. It's not available at all hospitals, and a trained specialist must perform the test.

For this test, a flexible tube called a catheter is threaded through the groin (upper thigh) or arm to the blood vessels in the lungs. Dye is injected into the blood vessels through the catheter.

X-ray pictures are taken to show blood flowing through the blood vessels in the lungs. If a blood clot is found, your doctor may use the catheter to extract it or deliver medicine to dissolve it.

Blood Tests

Certain blood tests may help your doctor find out whether you're likely to have PE.

A D-dimer test measures a substance in the blood that's released when a clot breaks up. High levels of the substance may mean there's a clot. If your test is normal and you have few risk factors, PE isn't likely.

Other blood tests check for inherited disorders that cause clots and 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.

Other Tests

To rule out other possible causes of your symptoms, your doctor may use one or more of the following tests.

• Echocardiogram. This test uses sound waves to check heart function and to detect blood clots inside the heart.
• EKG (electrocardiogram). An EKG measures the rate and regularity of your heartbeat.
• Chest x ray. This test provides a picture of your lungs, heart, large arteries, ribs, and diaphragm (the muscle below your lungs).
• Chest MRI (magnetic resonance imaging). This test uses radio waves and magnetic fields to make pictures of organs and structures inside the body. In many cases, an MRI can provide information that can't be seen on an x ray.