Pulmonary Embolism: Symptoms & Signs

Medically Reviewed on 9/10/2019

A pulmonary embolism occurs when a blood clot (deep vein thrombosis) travels through the veins and enters the heart, becoming trapped in the pulmonary artery that exits the heart to carry blood to the lungs. Thrombus is the medical term that refers to the blood clot, and the thrombus is referred to as an embolus if it breaks away from its site of formation and travels in the bloodstream. A pulmonary embolus clogs the pulmonary artery that provides blood supply to part of the lung. The embolus prevents the exchange of oxygen and carbon dioxide as well as decreases blood supply to the lung tissue itself. In this case, the lung tissue may die (or infarct). Chest pain and shortness of breath are the hallmark symptoms. Pulmonary embolism is a medical emergency and can be fatal. In some cases, it can lead to sudden death.

Causes of pulmonary embolism

Risk factors for the formation of the blood clot (thrombus) that travels to the lung (pulmonary embolism) include prolonged immobilization, including bed rest, certain medications, including birth control pills, smoking, genetic predisposition to blood clotting, an increased number of red blood cells (polycythemia), cancer, surgery, or damage to blood vessel walls.

Less commonly, other substances can enter the circulation and cause a pulmonary embolism, including amniotic fluid, fat cells (from a broken thigh bone), or cancer cells.

Other pulmonary embolism symptoms and signs


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Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.