PERC Rule

Rule out PE without D-dimer in LOW pre-test probability patients

Indication

id: age50; label: Age ≥ 50; type: yesno
id: hr100; label: Heart rate ≥ 100; type: yesno
id: spo2; label: SpO2 < 95% on room air; type: yesno
id: hemoptysis; label: Hemoptysis; type: yesno
id: estrogen; label: Estrogen use (OCP, HRT, pregnancy); type: yesno
id: dvtpe; label: Prior DVT or PE; type: yesno
id: surgery; label: Surgery or trauma requiring intubation/hospitalization in past 4 weeks; type: yesno
id: legswelling; label: Unilateral leg swelling; type: yesno

function(score) { if (score === 0) return { risk: '0/8', tier: 'PERC Negative', action: 'PE ruled out. No D-dimer or imaging needed. Sensitivity 97.4%, miss rate <2%.', color: 'green' }; return { risk: score + '/8 criteria positive', tier: 'PERC Positive', action: 'Cannot rule out PE by PERC alone. Proceed to D-dimer or Wells score.', color: 'red' }; }

PERC is a RULE-OUT tool — only use when your clinical suspicion is already LOW (<15%)
If ANY criterion is positive, PERC fails — proceed to D-dimer or Wells
PERC negative = no further workup needed for PE
Do NOT apply PERC to moderate or high pre-test probability patients