The winds of change continue to blow through the problem of thromboembolic disease. This is not surprising when the etiology still remains obscure. Venous thrombosis not infrequently complicates a variety of medical, surgical, and obstetrical conditions. Pulmonary embolism may cause death when the outcome of surgery might otherwise have been successful. Statistically, pulmonary embolism is the greatest single cause of postoperative deaths as well as the commonest postoperative chest complication. In spite of the growing awareness of thromboembolism this disease remains a constant source of unpleasant surprises.
The clinical diagnosis of incipient or even advanced venous thrombosis in the lower extremities is often impossible. Welch and Faxon1 found that in 128 cases of fatal embolism only 5% had clinical evidence of peripheral vein involvement. Coon and Coller2 reviewed a series of 595 cases of pulmonary embolism proved at autopsy. They found that only 7.1% had a clinical diagnosis