WHO project looks at venous thromboembolism and travel
Results from Phase I of the WHO Research Into Global Hazards of Travel (WRIGHT) project indicate that the risk of developing venous thromboembolism (VTE) approximately doubles after travel lasting four hours or more. However, the study points out that even with this increased risk, the absolute risk of developing VTE, if seated and immobile for more than four hours, remains relatively low at about 1 in 6,000.
The two most common manifestations of VTE are deep vein thrombosis and pulmonary embolism. Deep vein thrombosis (DVT) is a condition in which a blood clot, or thrombus, develops in a deep vein - usually in the lower leg. Symptoms of DVT are principally pain, tenderness and swelling of the affected part. DVT can be detected through medical testing and can be treated. It can be life-threatening when associated with thromboembolism.