The purpose of this study was to find out whether people flying long-haul developed clots in the leg. Before this paper was published deep vein thrombosis (DVT) had been mentioned in a few case reports. We thought that flying might cause clots, some of which could be very serious. We used colour duplex ultrasound imaging to detect very small clots. We found these in 12 out of 100 passengers flying long-haul.
All these clots were small, and in most passengers, dissolved without treatment. In the remaining passengers anti-coagulants were given and the clots all dissolved before they became important. What this study has shown is, that it is extremely common to develop small clots. We still do not know how many passengers will go on to get a bigger clot, either affecting the leg on a long-term basis, or travelling to the lung. At the same time we studied these passengers, a further 100 passengers were fitted with Medi-travel elastic stockings.