title: Compression sonography in patients with indeterminate or low-probability lung scans: lack of usefulness in the absence of both symptoms of deep-vein thrombosis and thromboembolic risk factors.
abstract: OBJECTIVE
  We sought to determine whether compression sonography could be eliminated in the evaluation of patients who lacked both thromboembolic risk factors and symptoms of deep-vein thrombosis and who had an indeterminate or low-probability lung scan.
  
  
  METHODS
  The medical records of 155 consecutive patients who underwent bilateral lower-extremity sonography after an indeterminate or low-probability lung scan were reviewed. The presence of thromboembolic risk factors and deep-vein thrombosis symptoms and the result of sonography were recorded. Patients were divided into two groups: group 1 consisted of patients with either thromboembolic risk factors or deep-vein thrombosis symptoms, 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-tailed Fisher's exact test.
  
  
  RESULTS
  Thromboembolic risk factors or deep-vein thrombosis symptoms were found in 109 of 155 patients (70%) (group 1). Deep-vein thrombosis was found in nine of 108 patients (8%) in group 1. Both thromboembolic risk factors and deep-vein thrombosis symptoms were absent in 47 of 155 patients (30%) (group 2). Deep-vein thrombosis was found in none of 47 patients (95% confidence interval, 0-8%) in group 2. The difference in the incidences of deep-vein thrombosis in groups 1 and 2 approached statistical significance (p = .0579). The negative predictive value of the absence of both thromboembolic risk factors and deep-vein thrombosis symptoms in excluding deep-vein thrombosis was 100% (95% confidence interval, 93-100%).
  
  
  CONCLUSIONS
  If both symptoms of deep-vein thrombosis and thromboembolic risk factors are absent, the usefulness of lower-extremity sonography in detecting deep-vein thrombosis in patients with an indeterminate or low-probability lung scan is low. The manner in which these findings may be used to modify individual practice patterns will undoubtedly depend on the rate of detection of deep-vein thrombosis at a given institution.
authors.affiliation: Department of Radiology, Beth Israel Hospital, Boston, MA 02215, USA.
authors.forename: M P
authors.initials: MP
authors.lastname: Rosen
authors.forename: R G
authors.initials: RG
authors.lastname: Sheiman
authors.forename: J
authors.initials: J
authors.lastname: Weintraub
authors.forename: C
authors.initials: C
authors.lastname: McArdle
mesh_terms: D000465:Algorithms; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007866:Leg / Q000098:blood supply; D008168:Lung / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000209:etiology; D011877:Radionuclide Imaging; D012307:Risk Factors; D013923:Thromboembolism / Q000150:complications / Q000453:epidemiology*; D013924:Thrombophlebitis / Q000150:complications / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D014463:Ultrasonography / Q000379:methods / Q000706:statistics & numerical data