Several studies have suggested that pulmonary embolism is an important cause of death in patients under going major surgery. These conclusions, however, are based on retrospective case-note analysis and the criteria for diagnosing fatal pulmonary embolism are often not defined. In this paper, we report the findings of a prospective, study involving 2,164 patients over the age of 40 undergoing major surgery. Age, sex, blood group, type of operation performed, the presence of malignancy and of

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... er factors which could possibly predispose to pulmonary embolism were recorded in each case. Operations performed included major abdominal, orthopaedic, gynaecological and urological procedures. The diagnosis of fatal pulmonary embolism was based on the presence at autopsy of emboli in the main pulmonary artery, its first division or the lobar arteries, with no other cause being found for the patient's death. One hundred patients died during the postoperative period and autopsy examination was performed in 73. Sixteen patients died due to fatal pulmonary embolism as defined above - an incidence of 0.73%. This was the commonest single cause of death recorded, others being pneumonia (13 patients), myocardial infarction (13 patients), peritonitis (9 patients) and miscellaneous (22 patients). The significance of the various factors which may influence the incidence of fatal pulmonary embolism will be discussed.