Computerized strain-gauge plethysmography - An alternative method for the detection of lower limb deep venous thrombosis?

AIM: To test the ability of computerized strain-gauge plethysmography to ac t as a screening test for lower limb deep venous thrombosis (DVT). MATERIALS AND METHODS: Over an 8-month period, all patients referred to our Medical Assessment Unit with suspected lower limb DVT were considered for inclusion in the study. Each patient underwent both plethysmography and asc ending venography within 24 h, and the presence or absence of thrombus in t he popliteal, superficial femoral or iliac veins was noted. The results of the two tests were then used to determine the accuracy of computerized stra in-gauge plethysmography in detecting above knee DVT. RESULTS: The screening tests and venograms of 239 patients referred with cl inically suspected lower limb DVT were compared. The false negative rate of plethysmography was 15.4%, which is significantly different from the 4.8% claimed by the manufacturers of this device (P = 0.00003). CONCLUSIONS: In a population of acute admissions with suspected lower limb DVT, computerized strain-gauge plethysmography is not suitable for use as a screening test due to an unacceptably high proportion of false negative sc reens. (C) 2000 The Royal College of Radiologists.