Air travel and risk of venous thromboembolism.

※ Venous thromboembolism (VTE) consists of two related conditions caused by blood clots: deep vein thrombosis (DVT) and pulmonary embolism (PE). ※ DVT is a condition in which a blood clot develops in one of the deep veins, most commonly in the lower legs. If part of the clot breaks off, travels and becomes lodged in the blood vessels of the lungs, it will cause PE. ※ In healthy individuals, the risk of VTE per more than 4-hour flight is about 1 in 6 000. The risk would increase with increasing travel duration, multiple flights within a short period, and pre-existing risk factors for VTE.