Scores & indices
Wells DVT score calculator
Ten criteria — including the minus two a credible alternative diagnosis earns — decide between a blood test and an ultrasound.
How to read the result
Wells (DVT) falls into these published bands.
A patient on active cancer treatment with tenderness along the deep venous system and a calf more than 3 cm larger than the other side.
Wells (DVT) 3 — DVT likely
At or above the two-level threshold: proceed to proximal-leg ultrasound; a D-dimer cannot rule out DVT at this probability.
Who this is for
For clinicians assessing a swollen or painful leg for deep-vein thrombosis. The two-level Wells strategy (Wells 2003) anchors the work-up: below 2, DVT is unlikely and a negative D-dimer ends it without imaging; at 2 or more, DVT is likely and the pathway goes to proximal-leg ultrasound — a D-dimer cannot exclude DVT at that probability.
How it works
What it calculates
Pre-test probability of deep-vein thrombosis from ten clinical criteria, including the −2 correction when an alternative diagnosis is at least as likely.
The two-level pathway
Score below 2: DVT unlikely — a negative D-dimer rules it out without imaging. Score 2 or more: DVT likely — proximal-leg ultrasound; a D-dimer cannot exclude DVT at this probability.
Limitations
Less reliable with prior ipsilateral DVT, and pregnancy needs a modified approach. Reference: Wells et al., NEJM 2003.
Built on published evidence
- Wells et al., NEJM 2003
Codification last reviewed 2026-08-28, and checked against published reference values in automated tests on every release — see the full evidence ledger.
Questions clinicians ask
Why does an alternative diagnosis subtract two points?
The score builds the competing diagnosis in: when cellulitis, a Baker's cyst, or a muscle tear is at least as likely, the −2 correction pulls the total down — sometimes below zero, which still simply reads as DVT unlikely.
Can a negative D-dimer rule out DVT at any score?
No. The D-dimer strategy was validated only in the unlikely group (score below 2). At 2 or more the pre-test probability is too high for a negative result to be trusted — those patients need a proximal-leg ultrasound.
Does the score work after a previous DVT in the same leg?
Less reliably — prior ipsilateral DVT distorts both the examination findings and the D-dimer, and pregnancy needs a modified approach. Previously documented DVT does score a point, but clinical judgement carries more weight in these groups.
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