⚕️ For clinical reference only. Not a substitute for professional judgment.

Wells Score — PE Pulmonary Embolism

Pre-test probability for pulmonary embolism. Guides D-dimer vs direct CT-PA decision.

Low Probability

Select criteria present.

Clinical Criteria

Clinical signs/symptoms of DVT (leg swelling + tenderness)+3 PE more likely than alternative diagnosis+3 Heart rate >100 bpm+1.5 Immobilisation ≥3 days or surgery in past 4 weeks+1.5 Previous DVT or PE+1.5 Haemoptysis+1 Malignancy (treated in last 6 months or palliative)+1

When to use

Suspected PE in haemodynamically stable patients
Score ≤4: D-dimer first (PERC rule if very low risk)
Score >4 (or "likely"): direct CT-PA
Haemodynamically unstable → urgent CT-PA or bedside echo — skip scoring

Formula / Thresholds

≤1 = Low (~5% PE prevalence)
2–4 = Moderate (~28%)
≥5 = High (~59%)

Alternative dichotomised:
≤4 = PE "unlikely" → D-dimer
>4 = PE "likely" → CT-PA

References

Wells PS et al. Ann Intern Med. 2001.
NICE CG144 — Venous thromboembolic diseases. 2020.
ESC Guidelines on Pulmonary Embolism 2019.