title: Is it useful to also image the asymptomatic leg in patients with suspected deep vein thrombosis?
abstract: BACKGROUND
  Venous ultrasonography is the cornerstone of the diagnostic work-up in patients with suspected deep vein thrombosis (DVT). Significant variations exist in clinical practice between centers and/or countries, e.g. proximal vs. whole-leg ultrasound, serial tests vs. single test, and combination with clinical probability and D-dimer testing. Fewer data exist on the need for bilateral leg imaging.
  
  
  OBJECTIVE
  To assess the yield of bilateral leg ultrasonography in patients with suspected DVT.
  
  
  METHODS
  This was a retrospective cohort study of consecutive patients with clinically suspected DVT. A single whole-leg ultrasound scan was performed in all patients. We extracted information on demographics, risk factors, clinical signs, pretest probability, side of clinical suspicion, and ultrasound results.
  
  
  CONCLUSIONS
  Among the 2804 included patients, 609 (21.8%) patients had a positive ultrasound finding. A total of 20 patients (0.8%; 95% confidence interval [CI] 0.5-1.2%) had a thrombus diagnosed in both the symptomatic leg and asymptomatic leg. Moreover, five patients (0.2%; 95% CI 0.1-0.5%) did not have a thrombus in the symptomatic leg but had a thrombus in the asymptomatic leg. Two of 2540 patients with unilateral symptoms had no proximal DVT in the symptomatic leg and a proximal DVT in the asymptomatic leg (0.08%; 95% CI 0.0-0.3%). In summary, systematic imaging of both legs in patients with suspected DVT has a very low yield, and therefore does not appear to be justified.
authors.affiliation: Ottawa Hospital Research Institute at the University of Ottawa, Ottawa, ON, Canada; Centre d'Investigation Clinique, Université de Brest, Brest, France.
authors.forename: G
authors.initials: G
authors.lastname: Le Gal
authors.forename: H
authors.initials: H
authors.lastname: Robert-Ebadi
authors.forename: M
authors.initials: M
authors.lastname: Carrier
authors.forename: C
authors.initials: C
authors.lastname: Kearon
authors.forename: H
authors.initials: H
authors.lastname: Bounameaux
authors.forename: M
authors.initials: M
authors.lastname: Righini
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D035002:Lower Extremity / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies; D013557:Switzerland; D018608:Ultrasonography, Doppler; D019564:Unnecessary Procedures; D014680:Veins / Q000000981:diagnostic imaging*; D020246:Venous Thrombosis / Q000000981:diagnostic imaging*
keywords: deep vein thrombosis; diagnosis; diagnostic imaging; thromboembolism; ultrasonography