About the Wells Score for PE
The Wells score for pulmonary embolism (PE) estimates how likely a PE is before imaging. The simplified seven-item version was derived by Wells and colleagues from a prospective cohort of patients with suspected PE and published in Thrombosis and Haemostasis in 2000. Points are weighted: clinical signs of DVT (3), PE as the most likely diagnosis (3), heart rate above 100 (1.5), immobilisation or surgery in the previous four weeks (1.5), previous DVT or PE (1.5), haemoptysis (1) and malignancy (1), for a maximum of 12.5.
Two interpretations were defined in the same paper. The two-tier rule classifies PE as unlikely at 4 points or less and likely above 4; combined with a negative D-dimer, an unlikely score left a PE rate of only 2.2% in the derivation set and 1.7% in validation. The three-tier rule groups scores below 2 as low, 2–6 as moderate and above 6 as high probability.
The score was developed in adults with suspected PE in emergency departments and inpatient wards. It structures the decision about D-dimer testing and CT pulmonary angiography; it does not diagnose or exclude PE by itself, and the "PE most likely" item relies on clinical judgement.
With the default inputs, the wells pe score is 4.5 / 12.5. Change any value above to recalculate instantly.
How to use the wells score for pe
- 1Use this for an adult in whom pulmonary embolism is suspected.
- 2Tick clinical signs of DVT and whether PE is the most likely diagnosis.
- 3Tick heart rate over 100, recent immobilisation or surgery, and previous DVT/PE.
- 4Tick haemoptysis and active malignancy if present.
- 5Read the two-tier result to decide between D-dimer and CT pulmonary angiography.
Formula and method
The seven variables and their weights came from logistic regression on 40 candidate clinical variables in a random 80% of a prospective cohort of patients with suspected PE, then were tested in the remaining 20%. The total ranges from 0 to 12.5.
Two-tier (dichotomised) rule: ≤ 4 PE unlikely, > 4 PE likely — 7.8% of patients scoring ≤ 4 had PE in the derivation study, falling to 2.2% when the D-dimer was also negative. Three-tier rule: < 2 low, 2–6 moderate, > 6 high probability. The dichotomised rule was later validated in the 3,306-patient Christopher Study (JAMA 2006).
- DVT
- Deep vein thrombosis
- VTE
- Venous thromboembolism (DVT or PE)
- HR
- Heart rate, beats per minute
Worked examples
Breathless, tachycardic, no other cause
PE as the most likely diagnosis (3) plus heart rate over 100 (1.5) gives 4.5: above 4, so PE is likely on the two-tier rule and moderate probability on the three-tier rule.
Pleuritic pain, alternative diagnosis more likely
Haemoptysis alone scores 1 point: PE unlikely and low probability. A D-dimer would usually be the next test.
Post-operative patient with a swollen leg
DVT signs (3), PE most likely (3), heart rate over 100 (1.5), recent surgery (1.5) and malignancy (1) total 10 — high probability; imaging is indicated.
Frequently asked questions
What Wells score means PE is likely?+
On the two-tier rule, a score above 4 means PE is likely and 4 or less means PE is unlikely. On the three-tier rule, below 2 is low, 2 to 6 moderate and above 6 high probability.
Can a D-dimer rule out PE?+
In patients with a Wells score of 4 or less (PE unlikely), a negative D-dimer makes PE unlikely enough that imaging can usually be avoided. In the Christopher Study only 0.5% of such patients had a venous thromboembolism in the next three months.
Why is “PE most likely” worth 3 points?+
The clinician’s overall judgement that PE is the leading diagnosis was one of the strongest predictors in the derivation study. It is subjective, which is why the Geneva score was developed as a fully objective alternative.
What is the PERC rule and how does it relate?+
The PERC rule is used in emergency patients with a low clinical suspicion of PE. If all eight PERC criteria are negative, PE can be excluded without a D-dimer. It is applied before or alongside a low Wells score.
Should I use the Wells score in pregnancy?+
The Wells score was not derived in pregnant patients and performs less well there. Pregnancy-specific approaches such as the YEARS algorithm adapted for pregnancy are used instead.
For healthcare professionals and education only. This calculator implements a published formula or score but is not a diagnosis and does not replace clinical judgment. Verify inputs and results against the original source before using them in patient care.
Sources
- Wells PS et al. Derivation of a simple clinical model to categorize patients’ probability of pulmonary embolism. Thromb Haemost 2000
- van Belle A et al. (Christopher Study). Effectiveness of managing suspected pulmonary embolism using an algorithm combining clinical probability, D-dimer testing, and CT. JAMA 2006