THE USE OF D-DIMER TESTING AND IMPEDANCE PLETHYSMOGRAPHIC EXAMINATIONIN PATIENTS WITH CLINICAL INDICATIONS OF DEEP-VEIN THROMBOSIS

Objective: To prospectively test the hypothesis that a diagnosis of de ep vein thrombosis can be excluded in outpatients who present with cli nical indications of deep vein thrombosis and whose results of D-dimer testing and impedance plethysmographic examination on the day of pres entation are normal. Design: Prospective cohort study. Setting: Four u niversity-affiliated hospitals. Methods: Three hundred ninety-eight co nsecutive patients with clinical indications of deep vein thrombosis w ere included in the final analysis. All patients underwent an assessme nt of pretest probability, bedside D-dimer testing, and impedance plet hysmographic examination. In most patients, if the results of D-dimer testing and impedance plethysmographic examination were negative for d eep vein thrombosis, anticoagulants were withheld and patients were fo llowed up for 3 months. If the results of one or both tests were abnor mal, an examination using venous compression ultrasonography or phlebo graphy was performed. Results: In the majority of patients (69%), the results of D-dimer testing and impedance plethysmographic examination were normal. This combination had a negative predictive value of 98.5% (95% confidence interval, 96.3-99.6) for deep vein thrombosis. Conclu sion: The results of the D-dimer assay and impedance plethysmographic examination on the day of presentation can be used to treat the majori ty of outpatients who present with clinical indications of deep vein t hrombosis without further testing.