PERC Score for Pulmonary Embolism

How to calculate the PERC Score?

The PERC rule is a clinical decision tool consisting of 8 specific criteria. Each positive finding adds 1 point to the total score.

Formula: Score = Σ(Criteria present)

Using the PERC calculator: an example

A 55-year-old patient presents with a Heart Rate of 105 bpm and no other findings.

Step-by-step calculation:

• Age ≥ 50: Yes (1 point)
• Heart Rate ≥ 100: Yes (1 point)
• Other 6 criteria: No (0 points)
• Final Score: 2 (Rule not satisfied)

Frequently Asked Questions

What is the primary use of the PERC rule?

It is used to safely avoid unnecessary testing like D-dimer or CT scans in patients whose pre-test probability of PE is already very low (<15%).

Does a score of 1 mean the patient has a PE?

No, it simply means the rule-out criteria were not met and the clinician should proceed with standard diagnostic pathways, such as a D-dimer test.

Who should NOT be evaluated with PERC?

Patients with a moderate or high clinical suspicion of PE should proceed directly to diagnostic imaging regardless of their PERC score.