What does PERC-negative mean?

PERC-negative means all 8 criteria are absent. In a patient with low clinical pre-test probability (< ~15%), a PERC-negative result allows the clinician to safely exclude PE without ordering a D-dimer or imaging.

Can PERC be used in all patients with suspected PE?

No. PERC is validated only for patients with LOW pre-test probability (gestalt < 15%). It should not be applied when pre-test probability is moderate or high — those patients require further workup regardless of PERC result.

What happens if one criterion is present?

A single positive criterion makes the patient PERC-positive, meaning PE cannot be ruled out by PERC alone. The next step is typically D-dimer testing, and potentially CT pulmonary angiography depending on D-dimer result and clinical judgment.

How accurate is the PERC Rule?

Prospective studies show a miss rate of less than 2% when PERC is applied correctly to low-probability patients. The rule has high sensitivity in this selected population.

Does this tool replace physician judgment?

No. PERC is a clinical decision support aid. It must be used alongside full clinical assessment, physician experience, and local protocols.

What is estrogen use in the context of PERC?

Estrogen use refers to oral contraceptives, hormone replacement therapy (HRT), or any other estrogenic medication. Estrogens increase thromboembolic risk and represent one of the PERC criteria.

PERC Rule for Pulmonary Embolism

Name: PERC Rule for Pulmonary Embolism
Availability: InStock
Author: Nham Vu

Check all 8 PERC criteria to determine if pulmonary embolism can be safely ruled out in low pre-test probability patients.

PERC Criteria

Check each criterion that is present in the patient. PERC applies only when clinical pre-test probability is low (< 15%).

If ALL criteria are absent, PE can be ruled out without further testing.

Age ≥ 50 years Heart rate ≥ 100 bpm O₂ saturation on room air < 95% Unilateral leg swelling Hemoptysis (coughing up blood) Recent surgery or trauma within 4 weeks requiring general anesthesia Prior PE or DVT diagnosis Estrogen use (oral contraceptives, HRT, or estrogenic medications)

Result

Criteria Present 0

out of 8 total criteria

0 8

PERC Negative

0 criteria present — PE can be ruled out if pre-test probability is low

Interpretation

PERC Negative (0 criteria) — No further workup needed if pre-test probability is low

PERC Positive (1+ criteria) — Further evaluation required; consider D-dimer or CT pulmonary angiography

Important: PERC is valid only when clinical pre-test probability is low (< 15%). Do not apply PERC to patients with moderate or high pre-test probability.

This tool is for educational purposes only. Clinical decisions should be made by qualified healthcare professionals.

Summary

Check all 8 PERC criteria to determine if pulmonary embolism can be safely ruled out in low pre-test probability patients.

How it works

Estimate clinical pre-test probability for PE — PERC applies only when that probability is low (below ~15%).
Check each of the 8 PERC criteria that applies to the patient.
If zero criteria are present (PERC-negative), PE can be ruled out without further testing.
If one or more criteria are present (PERC-positive), proceed with D-dimer testing or CT pulmonary angiography.
Always integrate findings with the full clinical picture and local institutional protocols.

Use cases

Avoid unnecessary D-dimer tests in low-risk ED patients with no PERC criteria.
Quickly screen patients presenting with chest pain or shortness of breath for PE likelihood.
Support clinical documentation for PE workup decisions.
Educate residents and students on evidence-based PE risk stratification.
Determine whether imaging is required before ordering a CT pulmonary angiogram.

Frequently Asked Questions

Last updated: 2026-06-09 · Reviewed by Nham Vu