PERC Rule for Pulmonary Embolism

Methodology

PERC (Kline 2004)

Negative only if all 8 criteria are absent

Applies only when the clinician's gestalt probability is already low; it is not a rule for all patients.

Who it is for

Adults in the emergency department whose clinician judges PE probability to be low (under 15%).

Version

1.0.0

How this calculator works

Where the formula comes from

• Kline and colleagues (2004) derived PERC from 21 variables in 3,148 emergency department patients evaluated for pulmonary embolism at 10 US hospitals, aiming to identify patients in whom a D-dimer test is not needed.^[1]
• In the low-risk validation group (1,427 patients) the rule had a sensitivity of 96% and specificity of 27%; the authors noted that its usefulness was limited by low specificity.^[1]

The inputs

• The eight criteria are age 50 or over, heart rate 100 or more, oxygen saturation 94% or less, unilateral leg swelling, haemoptysis, recent trauma or surgery, previous DVT or PE, and hormone use; the rule is negative only if all eight are absent.^[1]

Versions and alternatives

• In the PROPER cluster-randomised trial (2018, 1,916 patients with low clinical probability), a PERC-based strategy was non-inferior for thromboembolic events at three months and reduced CT pulmonary angiography (13% vs 23%).^[2]

Where accuracy falls (published evidence)

• A meta-analysis of 14,844 patients found pooled sensitivity of 97% and specificity of 22%, and recommended the rule for settings with low clinical probability.^[3]
• A European multicentre study (PERCEPIC, 2017) evaluated PERC in patients with low implicit clinical probability because its safety outside the US had been questioned.^[4]

What guidelines say

• The 2019 ESC guideline discusses PERC as a possible way to exclude PE without further testing in selected emergency department patients with low clinical probability.^[5]

Sources

1. Kline JA, Mitchell AM, Kabrhel C, Richman PB, Courtney DM. 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.1538-7836.2004.00790.x
2. Freund Y, Cachanado M, Aubry A, et al. Effect of the Pulmonary Embolism Rule-Out Criteria on subsequent thromboembolic events among low-risk emergency department patients: the PROPER randomized clinical trial. JAMA. 2018;319(6):559–566. doi:10.1001/jama.2017.21904
3. Singh B, Mommer SK, Erwin PJ, Mascarenhas SS, Parsaik AK. Pulmonary embolism rule-out criteria (PERC) in pulmonary embolism—revisited: a systematic review and meta-analysis. Emerg Med J. 2013;30(9):701–706. doi:10.1136/emermed-2012-201730
4. Penaloza A, Soulié C, Moumneh T, et al. Pulmonary embolism rule-out criteria (PERC) rule in European patients with low implicit clinical probability (PERCEPIC): a multicentre, prospective, observational study. Lancet Haematol. 2017;4(12):e615–e621. doi:10.1016/S2352-3026(17)30210-7
5. Konstantinides SV, Meyer G, Becattini C, et al. 2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism developed in collaboration with the European Respiratory Society (ERS). Eur Heart J. 2020;41(4):543–603. doi:10.1093/eurheartj/ehz405

Compiled from the published sources above. Every statement was agreed independently by three AI research tools (Claude, ChatGPT, DeepSeek) and its source verified in PubMed or Crossref by the Hakeemly editorial team. Not reviewed by a doctor unless stated. Agreed on 2026-10-11

Limitations

• Not validated in populations with high PE prevalence.

References

1. Kline JA, Mitchell AM, Kabrhel C, Richman PB, Courtney DM. 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.1538-7836.2004.00790.x