During the winter of 1977, the emperor of embolism stalked the land, shivering, no doubt, in his underwear! Since Dr. Eugene Robin spoke up, like the young child in the fairy story, challenging conventional widsom, retrospective studies have been published clarifying and refining the interpretation of ventilation-perfusion studies (1-6). Impedance plethysmography has gained stature as a safe and reliable noninvasive test for venous thrombosis in the popliteal fossa, or deep veins of the thigh (7, 8). Pulmonary angiography, the "gold" standard (1), with a mortality rate of 0.5% (9), remains the final arbiter, short of autopsy (10, 11).
The diagnosis