COMPRESSION SONOGRAPHY IN PATIENTS WITH INDETERMINATE OR LOW-PROBABILITY LUNG SCANS - LACK OF USEFULNESS IN THE ABSENCE OF BOTH SYMPTOMS OFDEEP-VEIN THROMBOSIS AND THROMBOEMBOLIC RISK-FACTORS

OBJECTIVE. We sought to determine whether compression sonography could be eliminated in the evaluation of patients who lacked both thromboem bolic risk factors and symptoms of deep-vein thrombosis and who had an indeterminate or low-probability lung scan, MATERIALS AND METHODS. Th e medical records of 155 consecutive patients who underwent bilateral lower-extremity sonography after an indeterminate or low-probability l ung scan were reviewed, The presence of thromboembolic risk factors an d deep-vein thrombosis symptoms and the result of sonography were reco rded, Patients were divided into two groups: group 1 consisted of pati ents with either thromboembolic risk factors or deep-vein thrombosis s ymptoms, and group 2 consisted of patients without thromboembolic risk factors and without deep-vein thrombosis symptoms, The incidences of deep-vein thrombosis in groups 1 and 2 were compared by use of a two-t ailed Fisher's exact test. RESULTS. Thromboembolic risk factors or dee p-vein thrombosis symptoms were found in 108 of 155 patients (70%) (gr oup 1). Deep-vein thrombosis was found in nine of 108 patients (8%) in group 1. Both thromboembolic risk factors and deep-vein thrombosis sy mptoms were absent in 47 of 155 patients (30%) (group 2), Deep-vein th rombosis was found in none of 47 patients (95% confidence interval, 0- 8%) in group 2, The difference in the incidences of deep-vein thrombos is in groups 1 and 2 approached statistical significance (p = .0579). The negative predictive value of the absence of both thromboembolic ri sk factors and deep-vein thrombosis symptoms in excluding deep-vein th rombosis was 100% (95% confidence interval, 93-100%). CONCLUSION. If b oth symptoms of deep-vein thrombosis and thromboembolic risk factors a re absent, the usefulness of lower-extremity sonography in detecting d eep-vein thrombosis in patients with an indeterminate or low-probabili ty lung scan is low, The manner in which these findings may be used to modify individual practice patterns will undoubtedly depend on the ra te of detection of deep-vein thrombosis at a given institution.