Thromboembolism is a syndrome of blockage by a thrombus or embolus of the main branches of the pulmonary artery that carry blood to the lungs. The condition can occur in anyone, even young and healthy people. But most often it affects people with diseases of the veins of the lower extremities and those that contribute to the development of complications after operations. Pathology rarely occurs on its own. Most often, it is combined with deep vein thrombosis and postthrombophlebitic syndrome, as well as as a complication of a localized source of inflammation, for example, chronic tonsillitis or carbuncle.