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PERC Rule Calculator

Apply the Pulmonary Embolism Rule-out Criteria (PERC) to determine if a low-risk patient can avoid further testing for PE.

Enter Values

Age < 50

Pulse < 100 bpm

SpO2 > 94% on room air

No Exogenous Hormone use

Result

Enter values above and click Calculate to see your result.

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Formula

8 criteria (All must be negative to "rule out")

If a patient is "low risk" by clinical judgment and meets all 8 PERC criteria, the risk of PE is less than 2%, making further testing unnecessary.

Worked Example

Age < 50, HR < 100, SpO2 > 94%, No unilateral leg swelling... -> PERC Negative (PE ruled out).

Frequently Asked Questions

What is the utility of PERC?

It allows doctors to "rule out" pulmonary embolism in low-risk patients without even ordering a D-dimer blood test.

What if one criterion is positive?

The PERC rule cannot be used to rule out PE. The clinician must proceed to further testing, typically starting with a D-dimer.

Can I use it on high-risk patients?

No. The PERC rule is only valid for patients where the clinician's "gestalt" or suspicion of PE is already low (< 15%).

Medical Disclaimer

This calculator is provided for informational and educational purposes only. It is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making any decisions based on these results. Do not disregard or delay seeking medical advice because of information obtained from this tool.

AI Assistant

Ask about this calculator

I can help you understand the perc rule calculator formula, interpret your results, and answer follow-up questions.

Try asking

Our AI assistant provides general estimates and advice only. Please consult a qualified healthcare professional before making any health-related decisions.

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