Asymptomatic pulmonary embolism. A common event in high risk patients.

Ventilation and perfusion lung scans were obtained before and at weekly intervals following hip surgery or major amputation in 158 patients. Pulmonary arteriograms were obtained in 21 of 33 patients developing perfusion patterns strongly suggesting embolism; 19 of the 21 arteriograms demonstrated pulmonary embolism. From autopsy and clinical data, 36 patients were diagnosed as having an embolus while under study, and 12 patients were suspected of having had an embolus during their illness but prior to entry into the study. Only four of these 48 patients experienced symptoms suggestive of pulmonary embolism. We conclude that asymptomatic pulmonary embolism is a common event in the populations studied.