Wells criteria
Background
- Clinical decision tool to estimate pre-test probability of pulmonary embolism
- Used to guide diagnostic workup: determines whether D-dimer alone can exclude PE or if imaging (CTPA) is needed
- Should be used in conjunction with clinical gestalt and the PERC rule
Criteria and Score
Wells Criteria
| Clinical Features | Points |
|---|---|
| Symptoms of DVT (leg swelling and pain with palpation) | 3.0 |
| PE as likely as or more likely than an alternative diagnosis | 3.0 |
| HR >100 bpm | 1.5 |
| Immobilization for >3 consecutive days or surgery in the previous 4 weeks | 1.5 |
| Previous DVT or PE | 1.5 |
| Hemoptysis | 1.0 |
| Malignancy (receiving treatment, treatment stopped within 6 mon, palliative care) | 1.0 |
Two Tier Wells Score
- Score 0-4 = PE Unlikely (12.1% incidence of PE)
- Check D-dimer
- If D-dimer positive then obtain CTPA or V/Q scan
- If D-dimer negative, no further workup needed (0.5% incidence of PE at 3 month follow up)
- Check D-dimer
- Score >4 = PE Likely (37.1% incidence of PE)
- Obtain CT Pulmonary Angiography or V/Q Scan
- New evidence suggests lower Wells Score with D-dimer <1000 ng/mL is effective at ruling out PE without imaging
Interpretation
- Low probability (score ≤4): Obtain D-dimer; if negative, PE effectively excluded
- Age-adjusted D-dimer cutoff (age × 10 for patients >50) improves specificity without sacrificing sensitivity
- High probability (score >4): Proceed directly to CTPA (D-dimer not useful — high false-negative rate)
- Alternative 2-tier model: PE unlikely (≤4) vs PE likely (>4)
Clinical Application
- If Wells ≤4 AND PERC rule negative → no further testing needed
- If Wells ≤4 AND PERC positive → obtain D-dimer
- If Wells >4 → obtain CTPA