PERC rule


  • Use only if you would be confident in excluding PE with a neg D-dimer
  • If all are present AND low suspicion for PE, no D-dimer needed:

PERC Rule Calculator

Check all of the following that are true:

  • Age <50yr
  • Pulse ox >94% (room air)
  • HR <100
  • No prior PE or DVT
  • No recent surgery or trauma (within prior 4wk)
  • No hemoptysis
  • No estrogen use
  • No unilateral leg swelling

In patients with low suspicion for PE (best-guess pre-test probability <15%) AND all are true, only 0.9% had PE (n=7527) and it can be ruled-out without further testing (i.e. no need for d-dimer)[1][2]


  • Validated on 7527 patients
    • Only 0.9% had PE when PERC negative, no deaths

See Also

Pulmonary Embolism (PE)

External Links

See Also


  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. (PMID: 18318689).