Deep vein thrombosis: ultrasound screening cannot accurately diagnose asymptomatic DVT.

Clinical bottom line (level 1a)

  1. Ultrasound scan cannot diagnose deep vein thrombosis in asymptomatic patients after orthopaedic surgery- further testing is required if the scan is abnormal.
  2. A negative ultrasound makes a deep vein thrombosis likely, but cannot completely rule it out.
Wells et al: Annals of Internal Medicine 1995; 122 (1): 47-51
Wells et al: Lancet 1995; 345: 1326-1330
Expires May 2003

The study

Systematic review of all of
  • Patients: asymptomatic patients
  • Intervention: ultrasound scan
  • Outcome: diagnosis of deep vein thrombosis


    • Articles found in English using MEDLINE, 1982 to October 1993 (search terms: ultrasound, orthopedics, post operative period, thrombophlebitis ) and bibliographic searches, search of Current Contents and handsearching recent journals

    Selection criteria: as above
    Appraisal criteria: two independent reviewers used set, stated criteria
    Articles excluded if: abstracts

    sixteen articles were identified (all on patients post-orthopaedic surgery; patients' mean age was between 66 and 82 years; majority had total knee or hip replacement)
    studies were found to be homogeneous

    The evidence


    diagnostic test deep vein thrombosis no DVT LR+
    (95% CI)    		 post-test probability LR-
    (95% CI)    		 post-test probability
    real-time B mode ultrasound scan 48 10 30
    (16 to 57)     		83% 0.40
    (0.30 to 0.53)     		6%
    duplex ultrasound scan 34 15 26
    (15 to 43)     		69% 0.22
    (0.12 to 0.39)     		2%
    colour Doppler ultrasound 13 24 8.4
    (4.7 to 15)     		35% 0.61
    (0.45 to 0.83)     		4%
    overall 95 49 19
    (14 to 25)     		66% 0.39
    (0.32 to 0.48)     		4%
    total

    • Prevalence of asymptomatic DVT was 9.5%.
    • Two trials reported on calf DVT, with a sensitivity of 48% for ultrasound scan (specificity not given).

    Comments

    1. Noted that trials that failed to meet all criteria (and excluded from the above analysis) had more favourable likelihood ratios.
    2. Ultrasound scan test characteristics are similar to symptomatic patients- the differences reflect the prevalence of DVT in the two groups.

    Citation

    1. Wells PS, Lensing AWA, Davidson BL, et al: Accuracy of ultrasound for the diagnosis of deep venous thrombosis in asymptomatic patients after orthopedic surgery: a meta-analysis. Annals of Internal Medicine 1995; 122 (1): 47-51
    2. Wells PS, Hirsch J, Anderson DR, et al: Accuracy of clinical assessment of deep-vein thrombosis. Lancet 1995; 345: 1326-1330
    Search Terms: DVT in Cochrane
    Contributor: Chris Ball and Clare Wotton, May 2000
    Reviewer:

    Clinical Question.
    Patient asymptomatic patients
    Intervention or Exposure ultrasound scan
    Outcome diagnosis of DVT