Pulmonary Embolism: Causes Make an Appointment Refer a Patient Ask a Question Reviewed by Chhaya Patel, MD (March 01, 2021) A pulmonary embolism, or PE, is a blockage of an artery in the lungs. This blockage most often happens when a blood clot occurs in an arm or leg, or other part of your body, detaches from inside the vein, and travels through the bloodstream to an artery in one of your lungs. The most common causes of pulmonary embolism (PE) are: Genetic defects can make some people more prone to clotting issues. Injury to pelvis, hip, knee or leg, or being immobile for a long time which does not allow the blood to circulate properly throughout the body. Cancer, heart diseases (including congestive heart failure atrial fibrillation), heart attack, and stroke, among other conditions, can make it more likely for a blood clot or PE to form. Medications related to hormones can increase the chance of blood clots forming. What increases your risk of having a pulmonary embolism? Being inactive or immobile for long periods of time due to bed rest, surgery or sitting A personal or family history of a blood clots Current or previous cancer treatment Being inactive during long periods of traveling A history of heart failure or stroke Being overweight or obese Injury or trauma to a vein from a recent surgery, facture or varicose veins Giving birth in the last six weeks Taking medication for birth control or hormone replacement therapy Having a central venous catheters in your arm or leg Pulmonary Embolism: Symptoms Clinical Trials For more than 100 years, National Jewish Health has been committed to finding new treatments and cures for diseases. Search our clinical trials.