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Evidence summaries

Diagnostic Strategies for Pulmonary Embolism

Negative lung scan, spiral computed tomography in combination with ultrasound, or quantitative D-dimer assay are adequate to rule-out PE where the population prevalence is 35% or less. Positive high probability ventilation perfusion lung scan, spiral computed tomography, or ultrasound are adequate to rule-in PE where the population prevalence is 35% or greater. Level of evidence: "A"

A systematic review 1 including 48 studies with a total of 11,004 subjects was abstracted in DARE. The included studies were required to use pulmonary angiography (confirmation strategies), and follow-up or pulmonary angiography (exclusion strategies) as the reference standard.

Confirmation strategies. The pooled positive LRs were as follows: high probability ventilation perfusion lung scan (1 study), 18.3 (95% CI: 10.3 to 32.5); spiral computed tomography (6 studies), 24.1 (95% CI: 12.4 to 46.7); ultrasonography of leg veins (4 studies), 16.2 (95% CI: 5.6 to 46.7). In patients with moderate (prevalence of PE 35% or greater) or high (prevalence of PE 70% or greater) pre-test probability, a positive finding on high probability ventilation perfusion lung scan, spiral computed tomography, or ultrasonography of the leg veins was associated with a greater than 85% post-test probability of PE.

Exclusion strategies. The pooled negative LRs were as follows: normal or near normal lung scan (9 studies), 0.05 (95% CI: 0.03 to 0.10); negative spiral computed tomography and leg vein ultrasonography (3 studies), 0.04 (95% CI: 0.03 to 0.06); D-dimer concentration of less than 500 microg/L as measured by quantitative enzyme-linked immunosorbent assay (11 studies; significant heterogeneity, quantitative latex agglutination tests excluded), 0.08 (95% CI: 0.04 to 0.18); negative spiral computed tomography (9 studies; significant heterogeneity), 0.11 (95% CI: 0.06 to 0.19); negative leg vein ultrasonography (6 studies; significant heterogeneity), 0.67 (95% CI: 0.50 to 0.89); negative D-dimer test measured by semi-quantitative latex agglutination (2 studies), 0.29 (95% CI: 0.03 to 2.46). In patients with low (prevalence of PE 10% or less) or moderate pre-test probability, a normal or near normal appearance on lung scan, a negative result on both spiral computed tomography and ultrasound, or a D-dimer concentration of 500 microg/L or less (measured by quantitative enzyme-linked immunosorbent assay) was associated with a less than 5% post-test probability of PE.

    References

    • Roy PM, Colombet I, Durieux P, Chatellier G, Sors H, Meyer G. Systematic review and meta-analysis of strategies for the diagnosis of suspected pulmonary embolism. BMJ 2005 Jul 30;331(7511):259. [PubMed] [DARE]

Primary/Secondary Keywords