Computer assisted strain-gauge plethysmography is a practical method of excluding deep venous thrombosis

AIM: To evaluate a computed strain-gauge plethysmograph (CSGP) as a screeni ng tool to exclude above knee deep venous thrombosis (DVT). METHODS: The first phase took place in the Radiology department. One hundre d and forty-nine patients had both Doppler ultrasound and CSGP performed. D iscordant results were resolved by venography where possible. The second ph ase took place in an acute medical admissions ward using a modified protoco l. A further 173 patients had both studies performed. The results were coll ated and analysed. RESULTS: Phase 1, The predictive value of a negative CSGP study was 98%, Th ere were two false-negative CSGP results (false-negative rate 5%), includin g one equivocal CSGP study which had deep venous thrombosis on ultrasound e xamination. Two patients thought to have thrombus on ultrasound proved not to have acute thrombus on venography, Phase 2, The negative predictive valu e of CSGP using a modified protocol was 97%. There were two definite and on e possible false-negative studies (false-negative rate 4-7%). CONCLUSION: Computer strain-gauge plethysmograph can provide a simple, chea p and effective method of excluding lower limb DVT. However, its use should be rigorously assessed in each hospital in which it is used. Goddard, A. J . P., Chakraverty, S. & Wright, J. (2001). Clinical Radiology 56, 30-34. (C ) 2001 rue Royal College of Radiologists.