title: A randomized trial of diagnostic strategies after normal proximal vein ultrasonography for suspected deep venous thrombosis: D-dimer testing compared with repeated ultrasonography.
abstract: BACKGROUND
  With suspected deep venous thrombosis and normal results on proximal vein ultrasonography, a negative d-dimer result may exclude thrombosis and a positive D-dimer result may be an indication for venography.
  
  
  OBJECTIVE
  To evaluate and compare the safety of 2 diagnostic strategies for deep venous thrombosis.
  
  
  METHODS
  Randomized, multicenter trial.
  
  
  METHODS
  Four university hospitals.
  
  
  METHODS
  810 outpatients with suspected deep venous thrombosis and negative results on proximal vein ultrasonography.
  
  
  METHODS
  Erythrocyte agglutination D-dimer testing followed by no further testing if the result was negative and venography if the result was positive (experimental) or ultrasonography repeated after 1 week in all patients (control).
  
  
  METHODS
  Symptomatic deep venous thrombosis diagnosed initially and symptomatic venous thromboembolism during 6 months of follow-up.
  
  
  RESULTS
  Nineteen of 408 patients (4.7%) in the D-dimer group and 3 of 402 patients (0.7%) in the repeated ultrasonography group initially received a diagnosis of deep venous thrombosis (P < 0.001). During follow-up of patients without a diagnosis of deep venous thrombosis on initial testing, 8 patients (2.1% [95% CI, 0.9% to 4.0%]) in the D-dimer group and 5 patients (1.3% [CI, 0.4% to 2.9%]) in the repeated ultrasonography group developed symptomatic venous thromboembolism (difference, 0.8 percentage point [CI, -1.1 to 2.9 percentage points]; P > 0.2). Venous thromboembolism occurred in 1.0% (CI, 0.2% to 2.8%) of those with a negative D-dimer result.
  
  
  CONCLUSIONS
  Seventy patients (8.6%) deviated from the diagnostic protocols, and 9 patients (1.1%) had inadequate follow-up.
  
  
  CONCLUSIONS
  In outpatients with suspected deep venous thrombosis who initially had normal results on ultrasonography of the proximal veins, a strategy based on D-dimer testing followed by no further testing if the result was negative and venography if the result was positive had acceptable safety and did not differ from the safety of a strategy based on withholding anticoagulant therapy and routinely repeating ultrasonography after 1 week.
authors.affiliation: McMaster University and the Henderson Research Centre, Hamilton, Ontario, Canada.
authors.forename: Clive
authors.initials: C
authors.lastname: Kearon
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Ginsberg
authors.forename: James
authors.initials: J
authors.lastname: Douketis
authors.forename: Mark A
authors.initials: MA
authors.lastname: Crowther
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Turpie
authors.forename: Shannon M
authors.initials: SM
authors.lastname: Bates
authors.forename: Agnes
authors.initials: A
authors.lastname: Lee
authors.forename: Patrick
authors.initials: P
authors.lastname: Brill-Edwards
authors.forename: Terri
authors.initials: T
authors.lastname: Finch
authors.forename: Michael
authors.initials: M
authors.lastname: Gent
mesh_terms: D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D005500:Follow-Up Studies; D006801:Humans; D007866:Leg / Q000098:blood supply; D008297:Male; D008875:Middle Aged; D018608:Ultrasonography, Doppler; D014680:Veins / Q000000981:diagnostic imaging*; D020246:Venous Thrombosis / Q000175:diagnosis* / Q000000981:diagnostic imaging
chemical_list: D005338:Fibrin Fibrinogen Degradation Products