What Causes Deep Vein Thrombosis?

In simplest terms: Inactivity causes blood flow to slow in the deep veins of the lower legs...

In a matter of a few hours, or less, blood can begin to pool and coagulate in the veins, producing an ever-enlarging and hardening blood clot. If or when this clot dislodges (often triggered by decompression after flight), it may move through the body's veins to the lungs or even to the heart where even a small clot can block critical blood flow causing rapid death or, at best, paralysis.

It is important to stress that Deep Vein Thrombosis may form very rapidly and become life threatening in only a matter of hours. However, many studies indicate that the passage of a clot to the lungs or heart may require a day or even weeks. This leads many researchers to believe that only a small percentage of travel-related DVT incidents are properly attributed to the real cause. (Our statistics on DVT may be, in reality, very low.)