PERC rule for pulmonary embolism

The Pulmonary Embolism Rule-out Criteria (PERC) identify low-risk patients in whom PE can be excluded without further testing. All eight criteria must be absent.

What goes into the PERC rule

Age ≥ 50 (+1)
Heart rate ≥ 100 (+1)
SpO₂ < 95% on room air (+1)
Unilateral leg swelling (+1)
Hemoptysis (+1)
Surgery or trauma within 4 weeks (+1)
Prior PE or DVT (+1)
Estrogen use (+1)

How to interpret the result

All 8 absent with low pre-test probability: PE excluded, no D-dimer needed
Any present: use Wells score and D-dimer

Clinical pearls

Apply only when clinical gestalt already puts probability below about 15%.
Not validated in hospitalized patients or in pregnancy.
Use PERC only after a structured pre-test probability assessment (gestalt or Wells).

Evidence

Kline JA, et al. Clinical criteria to prevent unnecessary diagnostic testing in emergency department patients with suspected pulmonary embolism. J Thromb Haemost. 2004;2:1247-1255.

Related workups

Pulmonary embolism Shortness of breath Chest pain

Related calculators

Wells score for PE sPESI All calculators

For education only. Check the inputs and the population the score was validated in before acting on it. Not a substitute for clinical judgment.