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)
• 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

See Also

• PERC rule
• Pulmonary embolism
• D-dimer
• Modified Wells Score
• DVT