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Alternative Names Return to topVenous thromboembolism; Lung blood clot; Blood clot - lung; Embolus; Tumor embolus
Definition Return to top
A pulmonary embolus is a blockage of an artery in the lungs by fat, air, a blood clot, or tumor cells.
Causes Return to top
A pulmonary embolus is most often caused by a blood clot in a vein, especially a vein in the leg or in the pelvis (hip area). The most common cause is a blood clot in one of the deep veins of the legs. This type of clot is called a deep vein thrombosis (DVT).
Less common causes include air bubbles, fat droplets, amniotic fluid, or clumps of parasites or tumor cells, all of which may lead to a pulmonary embolus.
Risk factors for a pulmonary embolus include:
People with certain clotting disorders may also have a higher risk.
Symptoms Return to top
Other symptoms that may occur:
Exams and Tests Return to top
The following lab tests may be done to see how well your lungs are working:
The following imaging tests can help determine where the blood clot is located:
Other tests that may be done include:
Treatment Return to top
Emergency treatment and a hospital stay are often necessary. The aim is to prevent new clots from forming. Oxygen therapy may be required to maintain normal oxygen levels.
In cases of severe, life-threatening pulmonary embolism, treatment may involve dissolving the clot and preventing new clots from forming.
Treatment to dissolve clots is called thrombolytic therapy. Clot-dissolving medications include:
Treatment to prevent clots is called anticoagulation therapy. Such drugs are commonly called blood thinners. Clot-prevention medicines include heparin and warfarin (Coumadin). Heparin or heparin-type drugs can be given intravenously (by IV, directly into a vein), or as injections under the skin. These are usually the first medications given, and are then transitioned over to warfarin given in pill form.
When you first start taking warfarin you will need frequent lab tests to check the thickness of your blood. This will help your doctor properly adjust your dose.
Patients who have reactions to heparin or related medications may need other medications.
Patients who cannot tolerate blood thinners may need a device called an inferior vena cava filter (IVC filter). This device is placed in the main central vein in the belly area. It keeps large clots from traveling into the blood vessels of the lungs. Sometimes a temporary filter can be placed and removed later.
Outlook (Prognosis) Return to top
It is difficult to predict how well a patient will do. Often, the outlook is related to what put the person at risk for pulmonary embolism (for example, cancer, major surgery, trauma). In cases of severe pulmonary embolism, where shock and heart failure occur, the death rate may be greater than 50%.
Possible Complications Return to top
When to Contact a Medical Professional Return to top
Go to the emergency room or call the local emergency number (such as 911) if you have symptoms of pulmonary embolus.
Prevention Return to top
Preventing deep venous thrombosis (DVT) is very important, especially in people at high risk. To help prevent DVT, move your legs often or take a stroll during long plane trips, car trips, and other situations in which you are sitting or lying down for long periods of time. Walking and staying active as soon as possible after surgery or during a long-term medical illness can also reduce your risk.
Heparin therapy (low doses of heparin injected under the skin) may be prescribed for those on prolonged bedrest.
Sometimes patients in the hospital wear special soft boots that automatically (and gently) squeeze the calves periodically. This is called intermittent pneumatic compression. It helps keep blood moving and prevents blood clotting.
References Return to top
Anderson DR, Kahn SR, Rodger MA, et al. Computed tomographic pulmonary angiography vs ventilation-perfusion lung scanning in patients with suspected pulmonary embolism: a randomized controlled trial.JAMA. 2007;298(23):2743-53.
Righini M, Le Gal G, Aujesky D, et al. Diagnosis of pulmonary embolism by multidetector CT alone or combined with venous ultrasonography of the leg: a randomised non-inferiority trial. Lancet. 2008;371(9621):1343-52.
Snow V, Qaseem A, Barry P, et al. Management of venous thromboembolism: a clinical practice guideline from the American College of Physicians and the American Academy of Family Physicians. Ann Intern Med. 2007;146(3):204-10. Epub 2007 Jan 29.
Tapson VF. Pulmonary embolism. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 99.Update Date: 1/27/2009 Updated by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.