Definition

A pulmonary embolism (PE) is a blockage in a blood vessel of the lungs. This lowers oxygen levels in the lungs and raises blood pressure in the vessels. It can be deadly in some people.

Pathway of Pulmonary Embolism Copyright © Nucleus Medical Media, Inc.

Causes

A PE is often caused by a blood clot in the leg or pelvis that travels to the lungs. Less common causes include floating pieces of fat, tumor tissue, or air.

Risk Factors

Having a blood clot in a deep vein of a leg or the pelvis raises the risk of PE. Other things that may raise the risk are:

• Lack of activity due to things like bed rest or a long trip
• Blood clotting disorders
• Recent surgery
• Bone fractures
• Cancer and cancer treatment
• Being overweight or obese
• Smoking
• Recent pregnancy or childbirth
• Some medicines, such as birth control pills and hormone replacement therapy
• Health problems such as stroke, heart disease, and high blood pressure

Symptoms

The symptoms of PE will depend on the size and location of the blockage. The amount of lung tissue that has reduced blood flow will also affect the symptoms. PE may cause:

• Problems breathing, such as shortness of breath and rapid breathing
• Chest pain
• Cough, sometimes with bloody phlegm
• Fever
• Feeling faint or lightheaded
• Seizures

Diagnosis

The doctor will ask about your symptoms and health history. A physical exam will be done.

Blood tests will be done to look for signs of a clot and to check oxygen levels.

Images may be taken. This may be done with:

• Chest x-ray
• CT scan
• Lung ventilation and perfusion scan
• Pulmonary angiogram
• Ultrasound
• MR angiogram
• Echocardiogram

An electrocardiogram (EKG) may be done to check the electrical activity of the heart.

Treatment

Treatment depends on the size of the clot and the symptoms it is causing. Emergency treatment may be needed.

Prevention

To lower the risk of blood clots that cause PE:

• Break up long periods of sitting. Get up and walk every few hours.
• People who have had a recent illness or surgery should begin to walk as soon as it is safe to do so.