Seasonal variations of deep vein thrombosis and its influence on the location of the thrombus.

The role of season as a predisposing factor for the development of deep vein thrombosis is controversially discussed. We analysed retrospectively seasonal variations in the occurrence of deep vein thrombosis of the leg in 905 patients between 1996 and 2000. Additionally, we evaluated the relationship between the season and the location of the thrombus. Our study revealed that the frequency of deep vein thrombosis of the leg was significantly higher during the winter half than during the summer half (p < 0.001). Regarding the seasonal variation of the location of the thrombus, distal deep vein thrombosis was more frequent during the winter half while proximal deep vein thrombosis was diagnosed more often during the summer half of the year. In conclusion, we suggest that the season has an influence on the development of deep vein thrombosis in the leg as well as on the location of the thrombus. Copyright 2002 Elsevier Science Ltd.