Small heparin doses as prophylaxis against deep-vein thrombosis in major surgery

100 patients were treated either with heparin 5,000 i.u. every 12 hours or placebo in a double-blind, randomized, prospective trial. The treatment was commenced 1-3 hours before surgery and was continued for 6 1/2 days. The criteria for the selection of patients and the principles on which the treatment and investigation schedules were based corresponded generally to those laid down by Kakkar et al. (1972). The incidence of deep-vein thrombosis of the lower extremities was 6% in the group treated with heparin and 20% in the placebo group. The decisive diagnosis of thrombosis was based on the scanning of the lower extremities after administration of I125-fibrinogen. No case of pulmonary embolism occurred and no complications because of the treatment were noted. We propose to institute investigations on a larger scale to evaluate the prophylactic value of small heparin doses with respect to pulmonary embolism.