Question 1: Do objective criteria provide improved risk stratification over gestalt clinical assessment in the evaluation of patients with possible pulmonary embolism?

• Level A recommendations. None specified.
• Level B recommendations. Either objective criteria or gestalt clinical assessment can be used to risk stratify patients with suspected pulmonary embolism. There is insufficient evidence to support the preferential use of one method over another.
• Level C recommendations. None specified.

Estimation of pretest probability is imperative for proper interpretation of tests performed in the evaluation of patients with suspected pulmonary embolism. Pretest probability can be performed by either objective criteria (e.g., Geneva score, Wells Canadian score, Kline Charlotte criteria, Pisa model) or gestalt clinical assessment. With the advent of electronic charting, computer support aides should be developed that will facilitate pretest probability assessment.

Since publication of the 2003 ACEP clinical policy on PE, there have been more than 1,000 publications each year on the subject.

Question 2: What is the utility of the Pulmonary Embolism Rule-out Criteria (PERC) in the evaluation of patients with suspected pulmonary embolism?

• Level A recommendations. None specified.
• Level B recommendations. In patients with a low pretest probability for suspected pulmonary embolism, consider using the PERC to exclude the diagnosis based on historical and physical examination data alone.
• Level C recommendations. None specified.

The D-dimer assay for exclusion of pulmonary embolism has a high sensitivity but poor specificity. As the risks of additional testing in low-risk patients with a false-positive D-dimer may outweigh the benefits, the PERC were developed to select a population at such low risk of pulmonary embolism that D-dimer testing may be unnecessary. In order to be considered PERC negative, the following criteria must be met: age younger than 50 years, pulse rate less than 100 beats/min, SaO2 greater than 94% (at sea level), no unilateral leg swelling, no hemoptysis, no recent trauma or surgery, no previous PE or DVT, and no hormone use. To date, there have been no prospective outcome studies in the use of the PERC for clinical decision making.

Question 3: What is the role of quantitative D-dimer testing in the exclusion of pulmonary embolism?

• Level A recommendations. In patients with a low pretest probability for pulmonary embolism, a negative quantitative D-dimer assay (high sensitivity [e.g., turbidimetric, ELISA]) result can be used to exclude pulmonary embolism.
• Level B recommendations. None specified.
• Level C recommendations. In patients with an intermediate pretest probability for pulmonary embolism, a negative quantitative D-dimer assay (high sensitivity [e.g., turbidimetric, ELISA]) result may be used to exclude pulmonary embolism.

Although the D-dimer assay is not specific, the sensitivity of a negative D-dimer for pulmonary embolism is 93% to 96%. In low-risk patients, studies are consistent in that a negative D-dimer reliably excludes pulmonary embolism. In patients with intermediate pretest probability, studies that included intermediate pretest probability patients within their D-dimer strategy have either not reported the results separately or have had too few patients in this subgroup to draw any firm conclusion. A negative D-dimer should never be utilized to exclude pulmonary embolism in patients with high pretest probability.