Prevention of venous thromboembolism in surgical patients by low-dose heparin: prepared by the Council on Thrombosis of the American Heart Association.

Presently available data indicate that low-dose heparin will significantly diminish postoperative deep venous thrombosis and pulmonary embolism in patients over the age of 40 subjected to major elective abdomino-thoracic surgery. The schedule is 5,000 USP units of heparin subcutaneously beginning two hours before operation and continued every twelve hours (10,000 units per day) until the patient is discharged. Whether anticoagulent therapy should be continued after discharge should be decided on an individual basis. Preoperative tests for patients on this regimen should include an hematocrit, prothrombin time, partial thromboplastic time, and a platelet count. They should also not be receiving aspirin or other platelet anti-aggregating agents for five days before operation. The efficacy of this regimen is complemented by the fact that it is well tolerated by the patient and requires no laboratory monitoring. However, it does produce a definite but acceptably low frequency of minor intraoperative and postoperative bleeding. This low-dose regimen has not proved effective in open prostatectomy or major orthopedic operations. Data are not available concerning the drug's safety in patients receiving spinal or epidural anesthesia. Nor is it recommended for operations on the eye, brain or in patients who are experiencing an active thrombotic process. More than five million individuals over the age of 40 undergo major general surgical operations annually in this country. One or two out of each thousand of these patients will die postoperatively from pulmonary embolism. If low dose heparin prophylaxis in 80% effective, then the possibility exists of saving 4,000 to 8,000 lives annually. Such an impact might be realized if physicians are prepared to recommend the low-dose heparin regimen as primary prophylaxis for all hemostatically competent patients over the age of 40 who undergo abdomino-thoracic surgery.