What is the Wells score for DVT?

The Wells DVT score is a validated clinical prediction rule that combines nine clinical features into a single number to estimate the pre-test probability of deep vein thrombosis. It helps decide whether a patient needs a D-dimer test, a compression ultrasound, or both.

How is the Wells DVT score interpreted?

In the three-tier model, a score of 0 or less is low probability, 1 to 2 is moderate, and 3 or more is high. In the more common two-tier model, a score of 2 or more is DVT likely and below 2 is DVT unlikely, which then guides D-dimer and ultrasound pathways.

Why does an alternative diagnosis subtract points?

If a condition at least as likely as DVT can explain the leg symptoms, such as cellulitis or a ruptured Baker's cyst, the probability of DVT falls. The Wells rule reflects this by subtracting two points, which can move a patient into a lower-risk pathway.

What do I do with a DVT-unlikely result?

For a DVT-unlikely score, a negative high-sensitivity D-dimer can safely rule out DVT without imaging. A positive D-dimer or a DVT-likely score should be followed by a proximal leg compression ultrasound, per NICE and other guidelines.

Does the Wells DVT score replace imaging?

No. The score only estimates probability and directs the testing pathway. A definitive diagnosis of DVT still relies on compression ultrasound. The tool supports clinical judgement and local protocols rather than replacing them.

Wells Score for DVT — Gera Tools

What the Wells DVT score does

The Wells score for deep vein thrombosis is a clinical prediction rule that turns bedside findings into an estimated pre-test probability of DVT. By stratifying patients before any blood test or scan, it allows clinicians to use D-dimer testing and compression ultrasound efficiently and safely, avoiding unnecessary imaging in low-risk patients while ensuring high-risk patients are investigated promptly.

How it works

Each of the following clinical features scores +1:

Active cancer (treatment within 6 months, or palliative)
Paralysis, paresis, or recent plaster immobilisation of the leg
Recently bedridden ≥3 days, or major surgery within 12 weeks requiring anaesthesia
Localised tenderness along the deep venous system
Entire leg swollen
Calf swelling >3 cm compared with the asymptomatic leg (measured 10 cm below tibial tuberosity)
Pitting oedema confined to the symptomatic leg
Collateral superficial (non-varicose) veins
Previously documented DVT

One feature scores −2:

An alternative diagnosis is at least as likely as DVT.

The points are summed. In the two-tier model a total ≥2 is “DVT likely” and <2 is “DVT unlikely”. In the three-tier model ≤0 is low, 1–2 is moderate, and ≥3 is high probability.

Tips and example

A patient with active cancer (+1), a swollen entire leg (+1), calf swelling >3 cm (+1), and no equally likely alternative diagnosis scores 3 — high probability (three-tier) and DVT likely (two-tier), warranting compression ultrasound. Always pair the score with a high-sensitivity D-dimer where the pathway calls for it, and follow your local DVT protocol and clinical judgement.