Screening for lower extremity deep venous thrombosis: An improved plethysmographic and Doppler approach

Noninvasive screening of the lower extremities for deep vein thrombosis was performed bilaterally on 1,118 patients. Impedance plethysmography alone was used in 868. Venography in 135 revealed an accuracy of 88 per cent, with a false-negative rate of 5.3 per cent and a false-positive rate of 18.6 per cent. A combined ultrasonic Doppler and modified impedance technic was used in 250 patients. Venography in forty revealed an accuracy of 95 per cent, with a false-positive rate of 10 per cent and no undetected thrombi. The combined technic, emphasizing the more accurate modality in three anatomic areas, has proven sensitive, specific, and reliable as a screening test for deep venous thrombosis.