Light reflection rheography as a noninvasive screening test for deep venous thrombosis

Abstract

Study objective: To determine if light reflection rheography is a useful screening tool for the diagnosis of proximal leg deep venous thrombosis.

Design: Light reflection rheography was compared with duplex ultrasonography and/or contrast venography on emergency patients being evaluated for proximal leg deep venous thrombosis.

Setting: University hospital emergency department.

Type of participants: Seventy-five ED patients being evaluated for acute leg deep venous thrombosis.

Interventions: Seventy-five patients being evaluated for clinically suspected deep venous thrombosis had light reflection rheography performed on the involved extremity immediately before duplex ultrasonography and/or contrast venography. Duplex ultrasonography and/or contrast venography was the definitive diagnostic test.

Measurements and results: Seventy-five patients had light reflection rheography performed, 72 had duplex ultrasonography, 19 had contrast venography, three had contrast venography alone, and 16 had both duplex ultrasonography and contrast venography. A comparison of light reflection rheography with duplex ultrasonography and/or contrast venography reveals that 39 light reflection rheography examinations were true-negative, 17 were true-positive, one was false-negative, and 18 were false-positive. The sensitivity of light reflection rheography for the detection of proximal leg deep venous thrombosis is 94.4% (95% confidence interval [CI], 72.7-99.9%), the negative-predictive value is 97.5% (95% CI, 86.8-99.9%), the specificity is 68.4% (95% CI, 54.8-80.1%), and the positive-predictive value is 48.6% (95% CI, 31.4-66%).

Conclusion: Light reflection rheography proved to be an excellent screening tool for emergency patients with the clinical suspicion for an acute proximal leg deep venous thrombosis. A normal light reflection rheography examination was 97.5% accurate as a negative predictor. That is, a normal light reflection rheography excluded the diagnosis of proximal leg deep venous thrombosis when compared with duplex ultrasonography and/or contrast venography when the duplex ultrasonography and/or contrast venography showed no evidence of proximal leg deep venous thrombosis. An abnormal light reflection rheography does not equate to an acute leg deep venous thrombosis as the specificity was only 68.4%. An abnormal light reflection rheography mandates further diagnostic studies such as duplex ultrasonography and/or contrast venography to confirm a diagnosis of proximal leg deep venous thrombosis.