Wells Criteria for PE
Estimates pre-test probability of pulmonary embolism
How to use & interpret
The Wells score for pulmonary embolism estimates the pre-test probability of PE so the right next test is chosen. It is applied when PE is being considered, before imaging.
Using the two-tier version: 'PE unlikely' (≤4) allows a D-dimer — if negative, PE is excluded without imaging; 'PE likely' (>4) should proceed straight to CTPA (or V/Q). In 'PE unlikely' patients, consider the PERC rule or an age-adjusted D-dimer to further reduce unnecessary scanning. Wells estimates probability; it never confirms or excludes PE on its own.
Score interpretation
Score ≤1: ~8% PE probability
→ Consider D-dimer; if negative, PE excluded
Score 2–6: ~28% PE probability
→ D-dimer if score ≤4 (PE unlikely); CTPA if score >4 or D-dimer positive
Score ≥7: ~60% PE probability
→ CTPA without delay; consider empirical anticoagulation
Interpretation bands for the Wells PE. Apply clinical judgement and local guidance.
Frequently asked questions
When can I use an age-adjusted D-dimer?
In 'PE unlikely' patients over 50, an age-adjusted threshold (age × 10 µg/L) raises the cut-off and safely reduces imaging without missing significant PE. Use your lab's validated assay and threshold.
References
- Wells PS, et al. Derivation of a simple clinical model to categorize patients probability of pulmonary embolism. Thromb Haemost. 2000;83(3):416–20.
Related
Curated clinical cross-links plus same-class fallbacks.
- HERDOO2 Rule for Discontinuing Anticoagulation in Unprovoked VTE · Venous Thromboembolism
- RIETE Score for Bleeding Risk in VTE · Venous Thromboembolism
- Wells Criteria for DVT · Venous Thromboembolism
- PERC Rule for PE · Venous Thromboembolism
- Revised Geneva Score for PE · Venous Thromboembolism
- Wells DVT Score · Venous Thromboembolism
- ApixabanRecommendedDirect oral anticoagulant (DOAC) — Factor Xa inhibitor
- Edoxaban (AF Stroke Prevention / VTE)RecommendedDirect Factor Xa Inhibitor (DOAC)
Featured in these MRCEM clinical pathways
The Wells PE is covered in detail — with RCEM/NICE evidence base, indications and pitfalls — in the following exam-focused pathways on our sister siteReviseMRCEM.
MRCEM Primary / Intermediate / OSCE candidates: each pathway includes exam-style questions, RCEM/NICE citations, and FAQ summaries.
Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.