PERC Rule

PERC Rule: If all 8 criteria are negative AND pre-test probability is < 15%, PE is ruled out WITHOUT further testing.

Guidelines & Evidence

Verified

Last Review: 2026-07-17

When to Use

Ruling out Pulmonary Embolism (PE) without the need for D-dimer testing or imaging

Applying exclusively to patients deemed strictly "low risk" by clinician gestalt (pre-test probability < 15%)

Reducing false positive D-dimers and subsequent unnecessary, harmful CT pulmonary angiograms (CTPA)

Patient Population

Adult patients in the emergency department setting where the clinician considers PE as a diagnosis but assesses the overall clinical pre-test probability to be low (< 15%). The PERC rule should never be applied to moderate or high-risk patients.

How it Works

Scoring Variables

Age ≥ 50 years

Heart rate ≥ 100 beats per minute

Oxygen saturation < 95% on room air

Unilateral leg swelling

Hemoptysis

Recent surgery or trauma (within prior 4 weeks requiring general anesthesia)

Prior history of DVT or PE

Current use of exogenous estrogen (OCPs, hormone replacement)

Interpretation

0 Criteria Present	PERC negative. No further testing (D-dimer or CTPA) is indicated. Risk of PE is <2%.
≥ 1 Criterion Present	PERC positive. Cannot rule out PE clinically. Proceed to D-dimer testing.

Last Comprehensive Review: 2026-07-17

Recent Journal Updates

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Clinical Context

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Clinical Context

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Clinical Context

We think this might be relevant to the clinical guidance for PERC Rule — Pulmonary Embolism Rule-Out Criteria.

PERC Rule

When to Use

When to Use

Patient Population

How it Works

Scoring Variables

Interpretation

Clinical Pearls

Clinical Pearl

Known Limitations

Next Steps

Actionable Clinical Management

The Evidence

Derivation Study

Clinical criteria to prevent unnecessary diagnostic testing in emergency department patients with suspected pulmonary embolism.

Origins & History

Development Context

Recent Journal Updates

PERC Rule

When to Use

When to Use

Patient Population

How it Works

Scoring Variables

Interpretation

Clinical Pearls

Clinical Pearl

Known Limitations

Next Steps

Actionable Clinical Management

The Evidence

Derivation Study

Clinical criteria to prevent unnecessary diagnostic testing in emergency department patients with suspected pulmonary embolism.

Origins & History

Development Context

Recent Journal Updates