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PERC Rule for PE Rule-Out
Pulmonology / Thromboembolism
The Pulmonary Embolism Rule-out Criteria (PERC) can exclude PE in low-risk patients without further workup. All 8 criteria must be answered NO to rule out PE. Answer YES or NO for each criterion below.
1. Age ≥50 years
2. Heart rate ≥100 bpm
3. SpO₂ <95% on room air
4. Unilateral leg swelling
5. Hemoptysis
6. Recent surgery or trauma (requiring intubation/anesthesia within 4 weeks)
7. Prior DVT or PE
8. Estrogen use (OCP, HRT, or pregnancy)
Answered: 0/8 criteria
Reference
| PERC Result | Meaning | Next Step |
|---|---|---|
| All 8 NO | PERC Negative | PE excluded — no further workup needed |
| Any YES | PERC Positive | D-dimer testing or CTPA required |
Clinical Notes
Sensitivity ~97%, Specificity ~22%. PERC negative in a low pre-test probability patient reduces the probability of PE below the testing threshold (~1.8%).
Do NOT use PERC if: Wells score >4, clinical gestalt suggests moderate/high PE probability, or the patient is hemodynamically unstable.
Do NOT use PERC if: Wells score >4, clinical gestalt suggests moderate/high PE probability, or the patient is hemodynamically unstable.
For educational use only. Not a substitute for clinical judgment.
