THE interruption of deep venous pathways in the treatment and prevention of pulmonary embolism has come to be a generally accepted surgical procedure. The preferred sites for division when deep venous thrombosis is present, or when pulmonary infarction has taken place without evident thrombosis but the latter is suspected, have been the superficial femoral veins, the common femoral veins and, in a few cases, the external and common iliac veins. In the majority of cases, section of the above-named vessels has been adequate to prevent further extension of thrombosis, with its possible detachment of a fatal or near-fatal embolus. It . . .