Computer assisted strain-gauge plethysmography is a practical method of excluding deep venous thrombosis.
OBJECTIVE
To evaluate a computed strain-gauge plethysmograph (CSGP) as a screening tool to exclude above knee deep venous thrombosis (DVT).


METHODS
The first phase took place in the Radiology department. One hundred and forty-nine patients had both Doppler ultrasound and CSGP performed. Discordant results were resolved by venography where possible. The second phase took place in an acute medical admissions ward using a modified protocol. A further 173 patients had both studies performed. The results were collated and analysed.


RESULTS
Phase 1. The predictive value of a negative CSGP study was 98%. There were two false-negative CSGP results (false-negative rate 5%), including one equivocal CSGP study which had deep venous thrombosis on ultrasound examination. Two patients thought to have thrombus on ultrasound proved not to have acute thrombus on venography. Phase 2. The negative predictive value of CSGP using a modified protocol was 97%. There were two definite and one possible false-negative studies (false-negative rate 4-7%).


CONCLUSIONS
Computer strain-gauge plethysmograph can provide a simple, cheap 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 Radiology56, 30-34.
Goddard
A J
AJ
Department of Radiology, Bradford Royal Infirmary, Duckworth Lane, Bradford BD9 6RJ, UK.
Chakraverty
S
S
Wright
J
J
D000208:Acute Disease; D005188:False Negative Reactions; D006801:Humans; D010991:Plethysmography / Q000295:instrumentation / Q000379:methods*; D019095:Point-of-Care Systems; D011237:Predictive Value of Tests; D012815:Signal Processing, Computer-Assisted; D014463:Ultrasonography; D020246:Venous Thrombosis / Q000175:diagnosis* / Q000000981:diagnostic imaging