What are the Pulmonary Embolism Rule out Criteria (PERC)?

Updated: Dec 30, 2020
  • Author: Kamran Boka, MD, MS; Chief Editor: Guy W Soo Hoo, MD, MPH  more...
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In 2004, Kline conducted a prospective study looking at eight variables (see below) to rule out pulmonary embolism when clinical Gestalt was low in the patient with low pretest probability for having pulmonary embolism. [6] The rule-out test (with poor specificity of 27% in low-risk patients and 15% in very-low-risk patients) was validated in two studies. [15]

Pulmonary Embolism Rule out Criteria (PERC) are as follows:

  • Age greater than or equal to 50 years

  • Heart rate greater than or equal to 100 beats per minute

  • Arterial oxygen saturation (SaO2) on room air less than 95%

  • Venous thromboembolism

  • Recent (< 28 days) trauma or surgery

  • Unilateral leg swelling

  • Hemoptysis

  • Oral hormone use

Pulmonary embolism workup can be ruled out if (1) none of the above eight variables is positive and (2) there is a less than 15% (very low) pretest probability that the patient has a pulmonary embolism. A PERC evaluation is considered positive if any one of the eight criteria are met.

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