The spectrum of pulmonary embolism: twenty years later.

A ten-year analysis of the prevalence of pulmonary embolism found at autopsy examination has been repeated 20 years after a prior study. The frequency of all pulmonary embolism (12.3%) and of "major" pulmonary emboli (7.1%) remains essentially unchanged from that detected 20 years previously (13.6% and 8.6%). Less than 10% of patients had the clinical diagnosis of deep leg vein thrombosis, and only 9.3% had a definitive diagnosis of pulmonary embolism made during life. A sixfold variation in quarterly frequency and a twofold variation in annual prevalence were noted. Since these wide fluctuations in frequency are present, any assumptions regarding a changing disease pattern must be made with great caution. There is no evidence that fatal pulmonary embolism has decreased in frequency in recent years. An effort should be made to increase rate of detection of thromboembolic disease by more widespread use of one or more of the recently developed diagnostic procedures, or a larger segment of the hospital population at risk should receive prophylactic therapy with "low-dose" heparin sodium.