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 act 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 ascending venography within 24 h, and the presence or absence of thrombus in the popliteal, superficial femoral or iliac veins was noted. The results of the two tests were then used to determine the accuracy of computerized strain-gauge plethysmography in detecting above knee DVT.

RESULTS

The screening tests and venograms of 239 patients referred with clinically 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 screens.