Abstract
A consecutive, randomly allocated, controlled, double-blind clinical trial of the prophylactic effect of a single pre-operative low dose of heparin on the incidence o-post-operative deep-vein thrombosis showed no reducf tion in the number of thromboses detected. Fifty-five patients were given 5000 units of heparin subcutaneously 1-1½ hr pre-operatively and fifty-seven patients were given a placebo. The incidence of thrombosis detected by the doppler ultrasound was 14·5% in the heparin group and 12·3% in the control group. It is suggested that a further trial monitored by ultrasound is indicated in which low-dose heparin is given for various periods post-operatively in addition to a pre-operative dose.