Pulmonology

Wells Score for Pulmonary Embolism

7 inputsPulmonology

Assess pre-test probability of pulmonary embolism (PE).

Calculate

Wells' Criteria (PE) calculator

Result

0.0points

Low (~1.3%) — D-dimer first

How to use it

1
Check DVT signs. Leg swelling, erythema, tenderness along deep veins = 3 points.
2
Is PE most likely?. After reviewing ECG, CXR and bloods, if PE tops your differential = 3 points.
3
Apply pathway. Low + negative D-dimer = excluded. Moderate + negative D-dimer = excluded. High = CTPA directly.

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.

Suspected PE, haemodynamically stable: Standard triage tool in ED and AMU.
With PERC: If all PERC criteria absent in true low-probability, skip D-dimer.
Not for massive PE: Haemodynamic instability → CTPA or bedside echo immediately.

About the score

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.

Scoring criteria

Clinical signs and symptoms of DVT (leg swelling, tenderness): 3
PE is the #1 diagnosis or equally likely: 3
Heart rate > 100 bpm: 1.5
Immobilisation ≥3 days or surgery in previous 4 weeks: 1.5
Previous DVT or PE: 1.5
Haemoptysis: 1
Malignancy (on treatment, treated in last 6 months, or palliative): 1

Score interpretation

< 2Low probabilityD-dimer testing appropriate; CT-PA if D-dimer positive
2–6Moderate probabilityD-dimer or CT-PA depending on clinical context and D-dimer availability
> 6High probabilityProceed directly to CT-PA; do not use D-dimer to rule out

Guideline recommendation

ESC 2019 PE Guidelines recommend basing the diagnostic strategy on clinical probability, assessed with a validated score (Wells or revised Geneva) or clinical judgement (Class I, Level A). In patients with low or intermediate clinical probability, or PE unlikely, D-dimer testing (preferably with a highly sensitive assay) is recommended, and a normal result excludes PE without CT-PA (Class I, Level A). An age-adjusted D-dimer cut-off (age × 10 µg/L above 50 years) should be considered as an alternative to the fixed cut-off (Class IIa, Level B).

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.

A reference for clinicians and students, not medical advice. A score supports a decision; it does not make one. Check every result against the patient in front of you and your local protocol.

At a glance

Specialty: Pulmonology
Inputs: 7
Type: Points score
Guidelines from: ESC, BTS, AHA

Frequently asked questions

What Wells score rules out PE?

No score rules out PE on its own. A Wells PE score below 2 (low probability) or of 2–6 (moderate), or of 4 or less on the two-tier version (PE unlikely), 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.