PERC Rule
Rules out PE without further testing in low-probability patients.
What is PERC Rule?
Rules out PE without further testing in low-probability patients. PERC Rule is intended for use in: Adults.
How to Use the PERC Rule Calculator
- Enter Age ≥ 50.
- Enter Heart rate ≥ 100 bpm.
- Enter SpO2 < 95% on room air.
- Enter Unilateral leg swelling.
- Enter Hemoptysis.
- Enter Recent surgery or trauma (within 4 weeks, requiring anesthesia).
- Enter Prior DVT or PE.
- Enter Hormone use (oral contraceptives, HRT, or estrogenic hormone use).
- Click Calculate to see your result and interpretation.
Formula & Version
This calculator uses formula version 1.0, last reviewed September 2026.
Clinical Considerations & Limitations
- Only intended for patients the clinician has already judged to be low pre-test probability for PE — do not apply to patients with moderate/high pre-test probability.
References
- Kline JA et al., J Thromb Haemost 2004;2:1247-1255
Frequently Asked Questions
What is PERC Rule?
Rules out PE without further testing in low-probability patients.
Who is PERC Rule intended for?
Adults. Always confirm applicability to your specific patient before use.
What are the limitations of PERC Rule?
Only intended for patients the clinician has already judged to be low pre-test probability for PE — do not apply to patients with moderate/high pre-test probability.
What formula or reference does PERC Rule use?
Kline JA et al., J Thromb Haemost 2004;2:1247-1255
Is PERC Rule a diagnosis?
No. PERC Rule produces a score or estimate to support clinical decision-making — it is not a diagnosis and should be interpreted alongside full clinical judgement.
