Wells Score Calculator
Clinical probability scoring for venous thromboembolism, with separate criteria for deep vein thrombosis and pulmonary embolism.
Also searched as: Wells criteria · Wells score DVT · Wells score PE · two-level Wells score
Wells DVT Score
0
DVT unlikely. Consider D-dimer testing.
Wells criteria
The DVT and PE scores are different instruments that share a name. Choose the one that matches the presentation before you start scoring.
Wells criteria for DVT
| Item | Response | Points |
|---|---|---|
| Active cancer | Treatment within 6 months, or palliative | +1 |
| Paralysis or immobilisation | Paralysis, paresis, or recent plaster immobilisation of the lower limb | +1 |
| Recent immobility or surgery | Bedridden >3 days, or major surgery within 12 weeks | +1 |
| Localised tenderness | Along the distribution of the deep venous system | +1 |
| Leg swelling | Entire leg swollen | +1 |
| Calf swelling | >3 cm compared with the asymptomatic leg | +1 |
| Pitting oedema | Greater in the symptomatic leg | +1 |
| Collateral veins | Superficial, non-varicose | +1 |
| Previous DVT | Previously documented | +1 |
| Alternative diagnosis | At least as likely as DVT | −2 |
Wells criteria for PE
| Item | Response | Points |
|---|---|---|
| Clinical signs of DVT | Leg swelling and pain on palpation of the deep veins | +3 |
| PE is the most likely diagnosis | Or equally likely to any alternative | +3 |
| Heart rate | >100 bpm | +1.5 |
| Immobilisation or surgery | Immobilisation >3 days, or surgery in the previous 4 weeks | +1.5 |
| Previous PE or DVT | Objectively diagnosed | +1.5 |
| Haemoptysis | Present | +1 |
| Malignancy | Treatment within 6 months, or palliative | +1 |
Wells score interpretation
The DVT score uses three probability bands; the PE score is most commonly used in its two-level form.
DVT ≤0Low probability (~5%)
DVT unlikely. Consider D-dimer testing.
DVT 1–2Moderate probability (~17%)
DVT possible. D-dimer or ultrasound recommended.
DVT ≥3High probability (~53%)
DVT likely. Ultrasound recommended regardless of D-dimer.
PE ≤4PE unlikely
Consider D-dimer testing. If negative, PE is effectively ruled out.
PE >4PE likely
CTPA recommended. Do not wait for the D-dimer result before imaging.
NICE guidance on venous thromboembolic diseases describes the two-level Wells scores and the associated D-dimer and imaging pathways used in the NHS.
How to calculate a Wells score
- 1Decide whether you are assessing for DVT or PE and select the matching criteria set.
- 2Work through each criterion and record it as present or absent — items are not weighted equally.
- 3For DVT, remember to subtract 2 points if an alternative diagnosis is at least as likely.
- 4Total the points and read off the probability band.
- 5Apply the band to your local VTE pathway: an unlikely result generally leads to D-dimer, a likely result to imaging.
Common pitfalls
- Mixing the two criteria sets. The PE score has weighted items of 3 and 1.5 points; the DVT score is mostly 1-point items with a single −2.
- Using a D-dimer to exclude VTE when the score is in the likely band — a negative D-dimer does not exclude PE in that group.
- Applying the score in pregnancy or the postpartum period, where it has not been validated and separate pathways apply.
- Forgetting that the "alternative diagnosis" items are deliberately subjective and depend on a proper clinical assessment.
- Scoring on history alone without examining the leg for swelling, tenderness and collateral veins.
Frequently asked questions
- When should the Wells Score be used?
- The Wells Score is used when DVT or PE is suspected to determine pre-test probability and guide investigation. Use the DVT version for suspected leg thrombosis and the PE version for suspected pulmonary embolism. It informs whether to proceed with D-dimer testing or imaging.
- How do you interpret the Wells Score?
- For DVT: a score of 0 or less is low probability (approximately 5%) - consider D-dimer testing. A score of 1-2 is moderate probability (approximately 17%) - D-dimer or ultrasound recommended. A score of 3 or more is high probability (approximately 53%) - ultrasound recommended regardless of D-dimer. For PE: a score of 4 or less means PE unlikely - consider D-dimer. A score above 4 means PE likely - CTPA recommended without waiting for D-dimer.
- What is the difference between the Wells score for DVT and for PE?
- They are separate scores with different items and different weightings. The DVT score has ten criteria, mostly worth 1 point, with minus 2 points if an alternative diagnosis is at least as likely. The PE score has seven criteria weighted 1, 1.5 or 3 points.
- What is the two-level Wells score?
- The two-level version collapses the result into "likely" and "unlikely" bands rather than three probability levels. It is the form used in NICE guidance on venous thromboembolic diseases to decide between D-dimer testing and proceeding straight to imaging.
- Can the Wells score be used in pregnancy?
- No. The Wells scores were not validated in pregnancy or the postpartum period, and separate diagnostic pathways should be followed for suspected VTE in these groups.
Sources and further reading
This page is reference information for registered healthcare professionals. It is not medical advice and does not replace clinical judgement, local policy, or the current version of the source guidance. Always verify scores and thresholds against your own organisation's pathway before acting on them.
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