Pulmonary Embolism

A sudden blockage of an artery in the lung. In most cases, the blockage is caused by a blood clot that has traveled to the lung from a vein in the leg. At least 100,000 cases of pulmonary embolism occur in the United States every year.

A number of factors may contribute to the formation of a blood clot within a vein deep in the body. This condition is called deep vein thrombosis (DVT) and typically occurs in the lower legs, thighs, or pelvis. Certain types of surgery, especially hip and knee replacements, may cause clots to form in the leg. Long periods of inactivity, caused by prolonged bed rest or long plane rides or car trips, may decrease blood flow in the veins and predispose people to blood clots. Certain medical conditions, some of them inherited, also make people more prone to blood clots. The hallmark symptoms of DVT in the legs are swelling in the leg or along a vein in the leg, pain or tenderness in the leg, especially when standing or walking, increased warmth in the swollen or painful area of the leg, and red or discolored skin on the leg.


A clot in a leg vein that travels to the lungs and blocks a pulmonary artery can cause such symptoms as sudden shortness of breath, chest pain, cough that produces blood or bloody mucus, and rapid heart beat. If you have any of these symptoms, seek medical help immediately. A pulmonary embolism can cause low oxygen levels in the blood, permanent damage to part of the lung due to inadequate blood flow, and damage to other organs due to lack of oxygen. A pulmonary embolism can even be fatal, especially if left untreated.

Doctor’s use a number of different tests to diagnose pulmonary embolism. A standard chest x-ray may be used to rule out other conditions that may be causing the symptoms. A lung scan, also known as a ventilation-perfusion scan, uses radioactive tracers to study air flow and blood flow in the lungs. A spiral computerized tomography (CT) scan involves injecting a dye into the bloodstream and using a scanner that spirals around the body to create three-dimensional images of the lungs. In a pulmonary angiogram, a catheter is inserted into a large vein and threaded through the heart and into the pulmonary artery, which leads to the lungs. A special dye is injected through the catheter, and x-rays are taken as the dye travels through the arteries and into the lungs.

A pulmonary embolism is usually treated with one or more anticoagulants (blood thinners). Patients initially receive the drug heparin, which is injected under the skin. Sometimes doctors also prescribe warfarin, which is taken orally. Patients may continue to take anticoagulants even after the original clot has dissolved. In particularly severe cases, patients may be given thrombolytic drugs, or “clot-busters,” such as urokinase or tissue plasminogen activator, to dissolve the clot.

There are a few measures you can take to lower your risk of developing deep vein thrombosis and a pulmonary embolism. During long flights, get up and walk around the cabin every hour or so. Likewise, during long drives, park the car every hour or so and walk around. Drinking plenty of water can also reduce the risk of developing clots.