Wells Score for Pulmonary Embolism
Assess pre-test probability of pulmonary embolism (PE). Wells PE score stratifies patients into low, moderate, or high probability to guide CT-PA and D-dimer testing.
What is the Wells PE?
The Wells score for pulmonary embolism (PE) is the most widely used and validated clinical prediction rule for estimating pre-test probability of PE in patients presenting with suspected thromboembolic disease. It combines seven clinical variables — including clinical signs of DVT, heart rate, recent immobilisation or surgery, prior PE or DVT, haemoptysis, malignancy, and clinical judgement — to stratify patients into low, intermediate, or high probability groups. This stratification directly guides the diagnostic pathway: whether to proceed to CT pulmonary angiography (CT-PA) immediately, or to first perform D-dimer testing to safely rule out PE in low-risk patients.
When to use it
Apply to any patient presenting with acute dyspnoea, pleuritic chest pain, tachycardia, or other features suggesting PE. Use before ordering CT-PA or D-dimer to determine the appropriate diagnostic pathway. Do not apply after CT-PA has already been ordered without consideration of pre-test probability.
Scoring Criteria
Wells PE — Variables & Points
Clinical signs and symptoms of DVT (leg swelling, tenderness)
PE is the #1 diagnosis or equally likely
Heart rate > 100 bpm
Immobilisation ≥3 days or surgery in previous 4 weeks
Previous DVT or PE
Haemoptysis
Malignancy (on treatment, treated in last 6 months, or palliative)
Score Interpretation
Low probability
D-dimer testing appropriate; CT-PA if D-dimer positive
Moderate probability
D-dimer or CT-PA depending on clinical context and D-dimer availability
High probability
Proceed directly to CT-PA; do not use D-dimer to rule out
Guideline Recommendation
ESC 2019 PE Guidelines recommend using a validated clinical probability score (Wells or revised Geneva) before diagnostic imaging. In low-probability patients with a negative age-adjusted D-dimer, PE can be safely excluded without CT-PA (Class I, Level A).
Clinical Pearls
D-dimer has high sensitivity but low specificity — only use it to RULE OUT PE in low-to-moderate probability patients, never to confirm PE.
Age-adjusted D-dimer threshold (age × 10 µg/L in patients >50 years) increases specificity and reduces unnecessary CT-PA.
In high-probability patients, go straight to CT-PA — a negative D-dimer does NOT safely exclude PE when pre-test probability is high.
The two-tier model (PE likely vs unlikely, using cut-off of 4) is simpler and performs comparably for binary clinical decisions.
Always consider alternative diagnoses — pneumothorax, pneumonia, and ACS can mimic PE clinically.
Limitations
The "PE is most likely diagnosis" criterion introduces subjective clinical assessment.
Not validated in pregnant patients — use YEARS algorithm in pregnancy.
Low discriminatory value in haemodynamically unstable patients requiring emergency CT-PA regardless of score.
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Frequently Asked Questions
What Wells score rules out PE?
A Wells PE score of ≤1 (low probability) combined with a negative D-dimer (conventional or age-adjusted threshold) safely excludes PE without CT-PA in the majority of patients. This approach has a miss rate of <1% in large validation studies.
What is the difference between Wells PE and Wells DVT?
Wells PE estimates the probability of pulmonary embolism, while Wells DVT estimates the probability of deep vein thrombosis in the lower limbs. They share some overlapping variables (DVT history) but are distinct scores applied in different clinical presentations.
Should I use Wells or Geneva score for PE?
Both are validated and guideline-endorsed. The Wells score is more widely used in the UK and North America; the revised Geneva score is fully objective (no clinical judgement component). Clinical outcomes are comparable — use whichever your institution has adopted.