The current status of low‐dose heparin in the prophylaxis of thrombophlebitis and pulmonary embolism

Abstract The efficacy of low‐dose heparin in preventing postoperative venous thromboembolism has been well established in 27 clinical trials which have been published during the last 3 years. The largest study has been with patients undergoing general abdominal, thoracic, and urological operations. The incidences of isotopic deep vein thrombosis (25%) and extending thrombi likely to produce major pulmonary emboli (6.0%) in the control group have been reduced to 7% and 0.6%, respectively, in those who received heparin. The crucial question concerns the effect of low‐dose heparin in the prevention of fatal pulmonary embolism. This endpoint has been evaluated in a multicenter prospective randomized, controlled trial involving 4,121 patients; 2,076 of these were in the control group and 2,045 received heparin. Sixteen patients in the control group and only 2 in the heparin group were found to have died due to massive pulmonary embolism proved at autopsy. The difference was statistically significant ( p < 0.005). A careful objective analysis of operative and postoperative bleeding in 1,475 patients showed no statistically significant difference in the blood transfusion requirements or in the fall in the postoperative hemoglobin level either in the individual operative groups or in the group as a whole. However, the experience in patients undergoing total hip replacement demonstrates less evidence of benefit than in other groups of surgical patients. The published evidence and the clinical experience with low‐dose heparin prophylaxis should now be used to influence the practice habits of the profession for preventing fatal pulmonary embolism occurring after major surgery .