Wells Score for DVT Calculator
Wells Score for DVT Calculator
Estimate the clinical probability of deep vein thrombosis with the Wells score, using the two-level DVT-unlikely / DVT-likely interpretation current guidance recommends.
Wells Score for DVT
10 items → -2 to 9Localised tenderness along the deep venous system and a previously documented DVT; no alternative diagnosis
Scoring
- +1 each
- active cancer, leg paralysis/immobilisation, bedridden/recent surgery, deep venous tenderness, whole-leg swelling, calf swelling >3 cm, confined pitting oedema, collateral veins, previous DVT — nine items
- −2
- an alternative diagnosis at least as likely as DVT
- range
- −2 to 9; ≤1 is unlikely, ≥2 is likely
Worked example
Localised tenderness along the deep venous system and a previously documented DVT; no alternative diagnosis
Localised tenderness = +1 · previous DVT = +1
All other eight items = 0
Total 2 points → DVT likely, so proceed to proximal leg ultrasound
Wells DVT criteria
| Clinical feature | Points |
|---|---|
| Active cancer (treatment within 6 months, or palliative) | +1 |
| Paralysis, paresis, or recent plaster immobilisation of a leg | +1 |
| Bedridden ≥3 days, or major surgery within 12 weeks | +1 |
| Localised tenderness along the deep venous system | +1 |
| Entire leg swollen | +1 |
| Calf swelling >3 cm larger than the other leg | +1 |
| Pitting oedema confined to the symptomatic leg | +1 |
| Collateral superficial (non-varicose) veins | +1 |
| Previously documented DVT | +1 |
| Alternative diagnosis at least as likely as DVT | −2 |
Using the two-level Wells score
Wells DVT was originally published with a three-level interpretation — low, moderate and high probability — but current guidance has settled on the simpler two-level version: DVT unlikely at a score of 1 or below, DVT likely at 2 or above. The two-level split performs as well as the three-level one and is easier to apply consistently, which is why it is now the version embedded in most clinical pathways.
The score’s value lies in what it lets a clinician skip. DVT unlikely combined with a negative D-dimer excludes the diagnosis without imaging, which matters given how often leg swelling and pain present without thrombosis. Any other combination — DVT likely regardless of D-dimer, or DVT unlikely with a positive D-dimer — needs a proximal leg compression ultrasound.
The score has real limits worth stating plainly. It was derived and validated in ambulatory outpatients presenting with a first suspected DVT, and it performs less well in three groups: hospital inpatients, where competing causes of leg swelling are common and immobility already inflates the score; pregnant patients, in whom it has not been adequately validated and physiological leg swelling confounds several items; and patients with a previous DVT, where residual swelling and tenderness from the earlier event can score positive independent of any new clot.
Frequently asked questions
What does a Wells DVT score of 1 mean?
In the two-level interpretation, a score of 1 or below is ‘DVT unlikely’. Combined with a negative D-dimer, this excludes DVT without needing an ultrasound.
Can the Wells score exclude DVT without an ultrasound?
Only when the score is 1 or below (DVT unlikely) and the D-dimer is also negative. Any other combination requires a proximal leg ultrasound.
Why does the score subtract points for an alternative diagnosis?
Because a competing explanation — such as a muscle strain, cellulitis or a Baker’s cyst — genuinely lowers the probability that the findings represent DVT, and the minus-2 weighting reflects how strongly that consideration counts against the diagnosis.
Is the Wells DVT score reliable in pregnancy or in inpatients?
No, not to the same degree. It was derived in ambulatory outpatients with a first suspected DVT and performs less well in pregnancy, in hospital inpatients, and in patients with a previous DVT.
Related calculators
References
- Wells PS et al. Value of assessment of pretest probability of deep-vein thrombosis in clinical management. Lancet. 1997;350(9094):1795–8.
- NICE guideline NG158. Venous thromboembolic diseases: diagnosis, management and thrombophilia testing.
Medical Disclaimer: The tools and content provided here are for educational and reference purposes only. They are not intended to substitute for professional medical advice, diagnosis, or treatment. Clinical decisions should always be based on the comprehensive assessment of a qualified healthcare professional.