Wells DVT Score Calculator
Assess the clinical probability of deep vein thrombosis with the Wells DVT criteria — nine clinical points, minus two when an alternative diagnosis is at least as likely.
How it works
Sum of nine +1 clinical criteria, minus 2 if an alternative diagnosis is at least as likely · ≤0 low, 1–2 moderate, ≥3 high (three-tier model)
The Wells DVT score turns the bedside exam and history into a pre-test probability, which is what makes D-dimer testing useful: a low Wells score plus a negative D-dimer safely rules out DVT without imaging, while a high score usually goes straight to ultrasound. The alternative-diagnosis item is the only one that subtracts points, reflecting that a plausible competing explanation makes clot less likely. It is a probability tool, not a diagnosis.
Worked example
A patient with active cancer (1), calf swelling more than 3 cm (1) and localised deep-vein tenderness (1), with no equally-likely alternative diagnosis, scores 3 — the high-probability band, where ultrasound is typically the next step.
Frequently asked questions
What do I do with a low Wells score?
A low score combined with a negative D-dimer blood test makes DVT very unlikely and often avoids the need for ultrasound. This pathway should be applied by a clinician, not self-directed.
Is a two-tier version different?
Yes. Some protocols collapse the score into "DVT likely" (≥2) versus "unlikely" (<2). This calculator uses the original three-tier low/moderate/high model.
Can I rule out a clot with this alone?
No. The score only estimates probability. Ruling DVT in or out requires D-dimer, ultrasound and clinical judgement. Sudden leg swelling or breathlessness is an emergency — seek care.
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Educational clinical estimate only — not a diagnosis, medical advice, or treatment. Scores are screening aids that must be interpreted by a qualified clinician alongside the full clinical picture. Never make care decisions from this tool alone.