PERC Rule (Pulmonary Embolism Rule-out Criteria) Calculator

PERC Rule (Pulmonary Embolism Rule-out Criteria): Explanation and Clinical Context
The PERC Rule is a clinical decision tool used to identify patients with a very low probability of pulmonary embolism (PE), in whom further diagnostic testing can be safely avoided.
It includes 8 criteria: age > 50 years, heart rate > 100 bpm, oxygen saturation < 95%, prior history of PE or DVT, recent surgery or trauma, hemoptysis, estrogen use, and unilateral leg swelling.
If a patient meets none of these criteria (PERC negative), the risk of PE is extremely low, and testing such as D-dimer or imaging may be unnecessary in low-risk patients.
If any criteria are positive (PERC positive), further evaluation is warranted based on clinical context.

Reference:
Kline JA, et al. "Clinical criteria to prevent unnecessary diagnostic testing in emergency department patients with suspected pulmonary embolism." J Thromb Haemost. 2004;2(8):1247-1255. doi:10.1111/j.1538-7836.2004.00860.x