Wells Score Calculator for DVT
Estimate the pre-test probability of deep vein thrombosis (DVT) using the Wells clinical prediction score. Most findings add one point, while an equally or more likely alternative diagnosis subtracts two. The score sorts patients into likelihoods that guide whether to proceed with D-dimer testing or straight to ultrasound. Tick the findings that are present.
The Wells DVT criteria
Nine findings each add one point, and an equally or more likely alternative diagnosis subtracts two. See also the Wells score for PE. Source: Wells PS et al., N Engl J Med 2003;349:1227–1235.
Frequently asked questions
How is the Wells DVT score calculated?
Add one point for each of: active cancer; paralysis, paresis or recent plaster immobilization; being bedridden more than 3 days or major surgery within 12 weeks; localized tenderness along the deep veins; the whole leg swollen; calf swelling more than 3 cm larger than the other side; pitting edema confined to the symptomatic leg; collateral non-varicose superficial veins; and a previously documented DVT. Subtract two points if an alternative diagnosis is at least as likely as DVT. The total runs from −2 upward.
What do the Wells DVT categories mean?
In the three-tier version, a score of 0 or less is low probability (DVT unlikely, roughly 5%), 1–2 is moderate (about 17%), and 3 or more is high probability (DVT likely, 17–53%). In the widely used two-tier version, a score of 2 or more is “DVT likely” and under 2 is “DVT unlikely.” Most current pathways use the two-tier split, because it pairs cleanly with a single D-dimer decision. Remember that the total can be negative: subtracting two points for an equally likely alternative diagnosis puts a patient firmly in the unlikely group. The probabilities attached to each band come from the derivation cohorts and shift with the population being tested, so treat them as approximate.
What happens after the score?
A common pathway is: DVT unlikely (score < 2) → D-dimer; a negative high-sensitivity D-dimer rules DVT out, while a positive one prompts ultrasound. DVT likely (score ≥ 2–3) → proceed directly to compression ultrasound. The exact protocol depends on local practice and the D-dimer assay used, and is a clinical decision.
How is calf swelling measured?
Measure the calf circumference 10 cm below the tibial tuberosity on each leg; a difference of more than 3 cm on the symptomatic side scores the point. Measuring at a consistent landmark on both legs avoids over- or under-counting this criterion. Mark the tibial tuberosity on each side first, since measuring at different levels is the commonest way this item is mis-scored. The threshold is strict — the difference must exceed 3 cm, so a 2 cm difference scores nothing even when the swelling is obvious to the eye.
When should the Wells DVT score not be relied on?
The Wells DVT score is a pre-test probability aid for suspected lower-limb DVT, not a diagnosis, and it performs best when combined with D-dimer and imaging. Use clinical judgement in pregnancy, recurrent or upper-extremity DVT, and other situations the score was not derived for. This calculator is an educational reference, not medical advice.
This is a reference tool, not a diagnosis or medical advice. Results depend on the laboratory, assay and clinical context, and reference intervals vary between labs and by age and sex — always read your result against the range printed on your own report and discuss it with a qualified healthcare professional.
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