Incidence and risk factor of postoperative deep vein thrombosis in Japanese

It has been said that the incidence of postoperative deep vein thrombosis is significantly low in Japanese compared to Western peoples. The study was undertaken to investigate its incidence and risk factors in Japanese.One hundred and twenty patients undergoing major abdominal surgery were investigated for deep vein thrombosis. All patients underwent postoperative isotopic scanning of the legs using the 125I-fibrinogen technique. Systematic studies on blood coagulation and fibrinolysis were performed on the patients before and after operation.In 15 of 120 patients there was the isotopic evidence of deep vein thrombosis, which was confirmed by ascending phlebography in ten in whom this procedure was performed. Thrombosis was unilateral in five and bilateral in ten. There were no physical signs suggesting thrombosis nor further propagation of thrombi into the popliteal vein or more proximal veins in any case, although seven of them recieved urokinase treatment immediately after detection of thrombosis in calf veins.Deep vein thrombosis developed more frequently in patients older than 50 years and in female. Deep vein trombosis was mostly found in patients who had colorectal surgery. All except one had malignant disease. Ten of fifteen cases who developed deep vein thrombosis had complete study of blood coagulation and fibrinolysis showed definite hypercoagulability in thromboelastgram and increase of heparin tolerance compared to those who had no thrombosis. However, euglobulin lysis time was rather shortened, suggesting increased fibrinolysis.The incidence of deep vein thrombosis in our series is definitely low compared to many reports in Western literatures. The cause of the low incidence remain open. Whatever the cause, the differences that we have demonstrated provide the first objective evidence that deep vein thrombosis is truely less frequent in Japanese than in Western peoples.