Pulmonary Embolism Rule-out Criteria — 8-item rule to exclude PE without testing.
When to use: Applied in patients with LOW pretest probability for PE. If ALL 8 criteria are negative (PERC negative), PE can be excluded without D-dimer or CT-PA. Do not apply if pretest probability is intermediate or high.
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Formula
PERC Negative = ALL 8 criteria met:
Age <50, HR <100, SpO₂ ≥95%, No leg swelling, No haemoptysis,
No recent surgery, No prior VTE, No hormone use
Key Points for NEET PG
PERC only valid when pretest probability is LOW (clinical gestalt or Wells PE score <2)
PERC-negative has ~2% false-negative rate — acceptable threshold per guidelines
D-dimer is sensitive but non-specific; PERC avoids D-dimer testing entirely in low-risk patients
Wells PE score first classifies pretest probability; PERC applies only to low-probability group
CT-PA is test of choice for PE diagnosis — PERC avoids unnecessary radiation in low-risk patients
References
Prospective multicenter evaluation of the pulmonary embolism rule-out criteria · Journal of Thrombosis and Haemostasis (2008)
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