How it's calculated
Each criterion carries its own weight (1 to 3 points) rather than a flat 1 point per item. A total score >4 classifies PE as "likely"; ≤4 classifies it as "unlikely" (two-tier Wells model).
Two-tier interpretation
| Score | Category | Suggested next step |
|---|---|---|
| ≤ 4 | PE unlikely | D-dimer — if negative, PE is effectively excluded |
| > 4 | PE likely | CT pulmonary angiogram (or V/Q scan) |
Clinical use
- Like the DVT version, the Wells PE score is designed to pair with a D-dimer: PE-unlikely plus a negative D-dimer reliably excludes PE without CT imaging.
- The PERC (Pulmonary Embolism Rule-out Criteria) rule is often used alongside or before the Wells score in very low-risk patients, to decide whether D-dimer testing is even needed.
- "PE is the #1 diagnosis or equally likely" is the single highest-weighted and most subjective criterion — it reflects overall clinical gestalt rather than one fixed measurable sign.
- Age-adjusted D-dimer thresholds (age × 10 μg/L FEU, for patients over 50) further reduce unnecessary CT scans in the PE-unlikely group without missing clinically significant PE.
Frequently asked questions
What is the Wells PE score used for?
It estimates the pre-test probability that a patient's symptoms (like pleuritic chest pain or breathlessness) are due to pulmonary embolism, guiding whether D-dimer alone can exclude PE or CT imaging is needed.
What does a Wells PE score over 4 mean?
It classifies the patient as "PE likely" — D-dimer isn't reliable for exclusion in this group, so CT pulmonary angiogram (or a V/Q scan where CT isn't suitable) is the recommended next step.
What is the most heavily weighted criterion in the Wells PE score?
Two criteria carry the highest weight (+3 each): clinical signs/symptoms of DVT, and PE being the most likely or equally likely diagnosis compared to alternatives — the latter reflecting overall clinical judgement.
How does the Wells PE score relate to the PERC rule?
PERC is often applied first, in very low pre-test-probability patients, to decide whether D-dimer testing is needed at all — the Wells score is then used in patients where PE is being more actively considered.
References
- Wells PS, et al. Derivation of a simple clinical model to categorize patients probability of pulmonary embolism. Thromb Haemost. 2000;83:416-420.
- van Belle A, et al. Effectiveness of managing suspected pulmonary embolism using an algorithm combining clinical probability, D-dimer testing, and CT. JAMA. 2006;295:172-179.
- Righini M, et al. Age-adjusted D-dimer cutoff levels to rule out pulmonary embolism (ADJUST-PE). JAMA. 2014;311:1117-1124.