Pulmonary embolism: compression ultrasound could help diagnose PE.

Clinical bottom line (level 1b)

  1. A positive bilateral compression ultrasound made pulmonary embolism more likely (LR+10) , but could not rule it out (LR-0.73) .
Turkstra et al: Annals Internal Medicine 1997; 126 (10): 775-781
Expires October 2003

The study

Setting: teaching hospital, Holland

357 patients (aged range 18 to 92 years; mean 56, 56% female) suspected pulmonary embolism

Excluded if
  • aged <18



    • Independent blinded reference standard, applied in all patients from a consecutive appropriate spectrum.
    Reference standard:
    • perfusion lung scan in six views. PE was excluded if normal, and diagnosed if high-probability scan. Pulmonary angiography was performed if the scan was non-diagnostic
    Diagnostic test: Bilateral B-mode grey scale compression ultrasound of common femoral, popliteal and distal popliteal veins. Abnormal if venous segment could not be completely compressed.
    • Patients were followed for six months.

    The evidence

    pre-test probability of pulmonary embolism: 46%, (95% CI: 40% to 51%)

    diagnostic test pulmonary embolism no pulmonary embolism LR+
    (95% CI)    		 post-test probability LR-
    (95% CI)    		 post-test probability
    ultrasound positive 43 5 10
    (4.2 to 25)     		90% 0.73
    (0.66 to 0.81)     		38%
    total 149 178

    Comments

    1. If ultrasound scanning was performed before v/q scan, v/q scans would be reduced by 14%, and angiograms by 9%. 4.2% of all patients would be inappropriately treated using this method.
    2. If ultrasound was performed only on patients with non-diagnostic v/q scans, then angiograms would be reduced by 9%. 2% of all patients would be inappropriately treated
    3. The study states that "9/35 or 26% of patients with abnormal ultrasound scans would be treated inappropriately" if USS scans were done after non-diagnostic v/q scans. Using PIOPED data, patients with non-diagnostic scans have 21% chance of a PE. Post-test probability following compression ultrasound if positive is 74% - i.e. not diagnostic.
    4. Can study be used to infer diagnostic strategy for non-diagnostic v/q scan patients? Since this is a different population, the test performs less well.

    Citation

    1. Turkstra F, Kuijer PM, van Beek EJ, et al: Diagnostic utility of ultrasonography of leg veins in patients suspected of having pulmonary embolism. Annals Internal Medicine 1997; 126 (10): 775-781
    Contributor: Chris Ball and Clare Wotton, October 2000
    Reviewer:

    Clinical Question.
    Patient suspected pulmonary embolism
    Intervention or Exposure bilateral compression ultrasound
    Outcome diagnosis