Detection of deep venous thrombosis by impedance plethysmography

Ninety-eight limbs in sixty-seven patients supected of having lower extremity deep venous thrombosis were evaluated by physical examination, venous impedance plethysmography (IPG), and venography. Diagnosis based on physical signs commonly associated with deep venous thrombosis was false-positive in 43 to 66 per cent and false-negative in 26 to 73 per cent when compared with evidence obtained by venography. The overall accuracy of IPG was 94 per cent, with false-positive results occurring in 10 per cent and false-negative results in 4 per cent. IPG is sufficiently accurate to be considered a reliable screening test for lower extremity deep venous thrombosis.