title: Venous thromboembolism: detection by duplex scanning.
abstract: OBJECTIVE
  The usefulness of transcranial Doppler monitoring in identifying emboli in the arterial circulation has been established. We attempted to extend this technique to identify embolism in the venous circulation and to note any changes in embolism rate with anticoagulation.
  
  
  METHODS
  From March to July 1993, 218 patients were evaluated by duplex scan for deep venous thrombosis.
  
  
  RESULTS
  Sixty patients had positive study results; 26 scans (43%) demonstrated embolism. In five patients (19%) the emboli were also seen on a B-mode image, enabling us to estimate embolus size, which ranged from 200 to 5000 micrometer. Embolus counts varied from 5 to 800 per minute. Deep venous thrombosis was located in the iliofemoral vein in 2 patients, superficial femoral/profunda vein in 8, saphenofemoraal junction in 1, popliteal vein in 1, and the calf in 10. Concomitantly, studies in 158 patients were negative for deep venous thrombosis; embolism was detected in 4 patients (3%) in this group. In patients taking heparin, the embolus counts decreased 50% or more within 24 hours, and all embolism was abolished within 72 hours. Two patients died of pulmonary embolus.
  
  
  CONCLUSIONS
  Patients with duplex scans that are positive for deep venous thrombosis have a high incidence of ongoing embolism. Heparin appears effective in eliminating the microemboli detected. The relationship among microembolism, deep venous thrombosis, and clinically significant pulmonary embolism remains to be elucidated.
authors.affiliation: Department of Surgery, Harborview Medical Center, University of Washington School of Medicine, Seattle 98104, USA.
authors.forename: S C
authors.initials: SC
authors.lastname: Nicholls
authors.forename: J K
authors.initials: JK
authors.lastname: O'Brian
authors.forename: M G
authors.initials: MG
authors.lastname: Sutton
mesh_terms: D005268:Femoral Vein / Q000000981:diagnostic imaging; D006801:Humans; D011152:Popliteal Vein / Q000000981:diagnostic imaging; D012501:Saphenous Vein / Q000000981:diagnostic imaging; D013923:Thromboembolism / Q000000981:diagnostic imaging*; D013927:Thrombosis / Q000000981:diagnostic imaging*; D013977:Tibia / Q000098:blood supply; D018616:Ultrasonography, Doppler, Duplex / Q000295:instrumentation / Q000379:methods; D014680:Veins / Q000000981:diagnostic imaging