Abstract
Pulmonary embolism was first recognized as an important entity early in the nineteenth century. The evolution of our knowledge of this disorder has been reviewed with particular emphasis on the various diagnostic techniques which have been used to assist in its recognition. These have included physical examination to demonstrate the presence of classical physical signs, electrocardiography, biochemical tests, radiological examinations, pulmonary function tests, ultra-sound and methods employing radionuclides. The wide variety of techniques applied to this problem clearly indicates that no currently available test is entirely satisfactory alone. Probably the most significant advance in recent years has been the development of lung perfusion scanning which has provided at the very least a valuable screening test and a ready method of studying serially the natural history of the perfusion defects produced by thromboembolic disease.