Emergency Medicine Risk score Strong evidence Clinical review pending v1.0.0

Wells' Criteria for Pulmonary Embolism

What is the pretest probability of pulmonary embolism?

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About this tool

Seven-item pretest probability score for PE, reported in three-tier and two-tier (PE likely/unlikely) forms.

Intended use

Adults with suspected acute PE, combined with D-dimer and imaging in a diagnostic algorithm.

Outcome

Pretest probability of PE

Time horizon

Current episode

Derivation population

Inpatients and outpatients with suspected PE (Canadian derivation).

Limitations

'PE most likely' is subjective and heavily weighted.
Requires adaptation in pregnancy.

Clinical problems

Suspected pulmonary embolism Chest pain

Evidence

Evidence level

Strong evidence

Derived and externally validated in multiple cohorts (including prospective studies) and incorporated into major clinical guidelines. Methodology

Guideline status

Incorporated in the 2019 ESC acute PE guideline diagnostic algorithms.

Evidence summaries for this tool are awaiting independent clinical review. Statistics are shown only where they could be attributed to a specific publication.

References

Original publicationWells PS, Anderson DR, Rodger M, et al. Derivation of a simple clinical model to categorize patients probability of pulmonary embolism. Thromb Haemost 2000;83:416-420. Find on PubMed (opens in a new tab)
GuidelineKonstantinides SV, Meyer G, et al. 2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism. Eur Heart J 2020;41:543-603. Find on PubMed (opens in a new tab)

Version history

Version	Formula	Effective	Reviewer	Changes
v1.0.0	Wells 2000	2026-10-03	—	Initial implementation with reference test vectors.

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Clinical decision support only. Interpret results in the context of the individual patient and current guidance; HumanPulse does not replace professional medical judgment.