Pulmonary embolism
Usually caused by a blood clot, pulmonary embolism is a blockage of the pulmonary artery, the main artery in the lung. Symptoms include sharp chest pain, shortness of breath, fainting, and anxiety. A 2013 study found that 33.5 percent of patients with pulmonary embolism were sent home or admitted to hospitals with a wrong diagnosis. Pulmonary embolism can be mistaken for other conditions such as a heart attack or pneumonia.