Over a century ago, Virchow suggested that pulmonary embolism was related to thrombophlebitis of the lower extremities, but it remained for Homans6 in 1934 to conceive of ligation of the inferior vena cava as a physiologically sound procedure to prevent thromboembolic episodes in patients with venous thrombosis in the lower half of the body. Trendelenburg15 had already accomplished a successful ligation of this vessel, in 1910, for pelvic thrombophlebitis complicated by puerperal pyemia, and earlier surgeons performed ligations (with fatal outcome) necessitated by inadvertent injury to the vena cava during operative procedures. In 1937, Krotoski8 collected 48 instances of ligation from the world literature, and by 1958, when Dale3 presented 16 cases and once more reviewed the subject, the total number of published reports had increased tenfold to 468. In 1951, Collins and his associates2 recorded the largest individual series, 70 patients with ligation of