A pulmonary embolism (PE) is a blood clot that blocks the blood vessels supplying the lungs. The clot (embolus) most often comes from the leg veins and travels through the heart to the lungs. When the blood clot lodges in the blood vessels of the lung, it may limit the heart's ability to deliver blood to the lungs, causing shortness of breath and chest pain, and, in serious cases, death. The US surgeon general estimates that 100 000 to 180 000 deaths occur from PE each year in the United States and identifies PE as the most preventable cause of death among hospitalized patients. The January 9, 2013, issue of JAMA contains an article about management of PE.