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PERC Rule for Pulmonary Embolism

The PERC rule rules out PE without testing when pretest probability is low (<15%) and all 8 criteria are absent: age <50, HR <100, SpO₂ ≥95%, no hemoptysis, no estrogen use, no prior DVT/PE, no unilateral leg swelling, no recent surgery or trauma. Any positive criterion means PERC cannot be used to exclude PE.

  • Age (years)
  • Heart rate (/min)
  • Oxygen saturation (SpO₂) (%)
  • Unilateral leg swelling (yes/no, +1)
  • Hemoptysis (yes/no, +1)
  • Recent surgery or trauma (≤ 4 weeks, requiring general anesthesia/hospitalization) (yes/no, +1)
  • Previous DVT or PE (yes/no, +1)
  • Hormone use (oral contraceptives, HRT or estrogen) (yes/no, +1)
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Interpretation

ResultMeaning
0 positive (and low gestalt)PE ruled out, no further testing
≥ 1 positiveCannot exclude PE with PERC

Formula

PERC negative only if ALL: age < 50 · HR < 100 · SpO₂ ≥ 95% · no hemoptysis · no estrogen use · no prior DVT/PE · no unilateral leg swelling · no surgery/trauma requiring hospitalization in past 4 weeks

Clinical pearls

  • Only apply PERC when your gestalt pretest probability is already low (< 15%); it is not for moderate- or high-risk patients.
  • Validated in emergency department populations; use caution in high-prevalence settings (e.g. Europe) where miss rates were higher.

Examples

perc 32F hr 88 sat 98 on ocpperc rule for a 40 year old man, pulse 92, oxygen saturation 97%, no leg swelling, no prior clotscan i rule out pe 45M hr 105 sats 96

FAQ

When can I use the PERC rule?

Only when clinical pretest probability of PE is low (under about 15%); if all 8 criteria are negative, no D-dimer or imaging is needed.

Does one positive PERC criterion mean PE is likely?

No. It only means PERC cannot exclude PE; continue with Wells or Geneva and D-dimer.

Evidence

  1. Kline JA et al. Clinical criteria to prevent unnecessary diagnostic testing in emergency department patients with suspected pulmonary embolism. J Thromb Haemost 2004;2:1247–55.
  2. Kline JA et al. Prospective multicenter evaluation of the pulmonary embolism rule-out criteria. J Thromb Haemost 2008;6:772–80.

Cardiology · Reviewed 2026-10-14 · Methodology