Thrombosis at mountain altitudes.

Victims of high-altitude pulmonary edema often have clots obstructing the pulmonary vessels. This, together with an apparent high incidence of thrombophlebitis and cerebral emboli at altitude suggests that mountain travel may predispose to hypercoagulability. A critical analysis of the available data suggests that, although thrombosis may be a late event complicating various forms of mountain sickness, the laboratory techniques of characterizing hypercoagulability are not sufficient to define and characterize the mechanism.