PULMONARY EMBOLISM: ITS INCIDENCE AT NECROPSY IN RELATION TO PERIPHERAL

T H E most dangerous complication of venous thrombosis is pulmonary embolism, with its mortality of about 20 per cent.1 Such embolism has been reported by Barnes 3 to be responsible for 34,000 deaths in this country each year. Knauer 2 has reported fatal pulmonary embolism in 2.5 per cent of 33,558 autopsies. Hunter4 found that over 50 per cent of older people con-fined to bed evidenced thrombosis of the deep leg veins, with pulmonary emboli from these veins accounting for over 3 per cent of all deaths. The factors which determine whether a thrombus will or will not em-bolize are not fully understood. It is commonly assumed that the incidence of pulmonary embolism in any given age or disease group is a direct function of the incidence of thrombosis. If this were not so, the nature of the dis-orders with an altered frequency of embolization might serve as a clue to the understanding of embolization. Accordingly, a study was undertaken to determine if disease of any particular system enhanced or retarded the em-bolization of thrombi. This postmortem study was further stimulated by th