Blood Clot FAQs – Testing and Diagnosis

Q. How is a Deep Vein Thrombosis (DVT) diagnosed?Blood Cells

A. Most often, ultrasound is used to diagnose blood clots in the leg veins. This is a non-invasive test. If the results are not definitive, then venography (an invasive test using contrast dye) or MRI (magnetic resonance imaging) may be used.


Q. How is a Pulmonary Embolism (PE) diagnosed?

A. If the VQ scan does not identify a clot, but one is still suspected, a pulmonary angiogram is performed. A catheter is threaded through a vein in the groin, passed through the heart, and into the pulmonary artery. Contrast dye is then injected and X-rays are taken to monitor the blood flow in the lung. The angiogram will give a definite diagnosis as to the presence of a clot.

Occasionally, an echocardiogram will show abnormalities in heart function, particularly in the right ventricle, as it meets resistance in pumping blood into the lungs.

Q. Is the Ventilation-Perfusion VQ scan the best non-invasive method for detecting a PE?

A. It is the best current non-invasive technique for detecting a PE. Spiral CT (computed tomography) imaging is a new non-invasive technique being developed and has potential for replacing the VQ scan.

Q. Why did I get a chest X-ray?

A. To rule out pneumonia, another common cause of chest pain and breathing difficulty.

Q. Is it common for a Pulmonary Embolism (PE) to be misdiagnosed as a pulled muscle, pleurisy, anxiety, asthma, etc?

A. Yes. PE mimics many other diseases and is particularly difficult to diagnose.