Wells Score (Pulmonary Embolism)
Calculate the Wells score to estimate pre-test probability of pulmonary embolism.
Formula
Sum of 7 criteria. ≤1: low; 2–6: moderate; ≥7: high probability of PE
- Three-tier: ≤1 low (~10%), 2–6 moderate (~30%), ≥7 high (~65%).
- Two-tier: ≤4 PE unlikely (D-dimer test first); >4 PE likely (CT-PA).
- Per NICE NG158 and ESC 2019 PE guidelines.
Classic PE presentation
Inputs
- Clinical signs of DVT: 3
- Alternative diagnosis less likely than PE: 3
- Heart rate > 100: 1.5
- Immobilisation or surgery in previous 4 weeks: 0
- Previous DVT or PE: 0
- Haemoptysis: 0
- Active malignancy (on treatment, treated in last 6 months, or palliative): 0
3+3+1.5 = 7.5. High probability. CT-PA indicated.
Frequently asked questions
What do I do with a low Wells score?
With Wells ≤1 (or ≤4 two-tier), order a D-dimer. If negative, PE is excluded. If positive, CT-PA is needed. A negative D-dimer with low pre-test probability has >99% sensitivity for excluding PE.