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Wells Score for Deep Vein Thrombosis

Estimates the clinical pretest probability of lower-limb deep vein thrombosis to guide D-dimer testing and compression ultrasound.

The Wells score for DVT combines ten clinical variables into a pretest probability for lower-limb deep vein thrombosis. In the widely used two-tier version, "DVT likely" patients proceed to ultrasound and "DVT unlikely" patients are triaged with D-dimer.

🧮 Interactive Calculator

Active cancer (treatment within 6 months / palliative) (+1)

Paralysis, paresis or recent plaster immobilisation of leg (+1)

Bedridden ≥ 3 days or major surgery within 12 weeks (+1)

Localised tenderness along deep venous system (+1)

Entire leg swollen (+1)

Calf swelling > 3 cm vs asymptomatic leg (+1)

Pitting oedema confined to symptomatic leg (+1)

Collateral superficial (non-varicose) veins (+1)

Previously documented DVT (+1)

Alternative diagnosis at least as likely as DVT (−2)

📐 Formula

Sum of criteria (alternative diagnosis −2). ≥ 2 DVT likely; < 2 DVT unlikely.

When to Use

Adult patients with a swollen, painful lower limb and suspected DVT.
Before ordering D-dimer or compression ultrasound to stratify pretest probability.
Outpatient and emergency assessment of possible venous thromboembolism.

How It Works

Award +1 for each of nine positive criteria (active cancer, paralysis/immobilisation, bedridden/surgery, deep-vein tenderness, whole-leg swelling, calf swelling > 3 cm, pitting oedema, collateral superficial veins, previous DVT).
Subtract 2 if an alternative diagnosis is at least as likely as DVT.
Sum the points to obtain the total score.

Interpreting the Result

Two-tier: score ≥ 2 = DVT likely; score < 2 = DVT unlikely.
DVT unlikely + negative D-dimer: DVT excluded without imaging.
DVT likely (or positive D-dimer): proceed to compression ultrasound.
Original three-tier: 0 low, 1–2 moderate, ≥ 3 high probability.

Limitations & Pitfalls

Less well validated in inpatients, pregnancy and recurrent/known DVT.
The subtractive "alternative diagnosis" criterion is clinician-dependent.
A single negative ultrasound in a "likely" patient may require repeat imaging.

References

Wells PS, Anderson DR, Rodger M, et al. Evaluation of D-dimer in the diagnosis of suspected deep-vein thrombosis. N Engl J Med. 2003;349(13):1227-1235.
Wells PS, Hirsh J, Anderson DR, et al. Accuracy of clinical assessment of deep-vein thrombosis. Lancet. 1995;345(8961):1326-1330.

⚕️ For clinical decision support only. Always verify calculations and apply clinical judgment.

Wells Score for Deep Vein Thrombosis

🧮 Interactive Calculator

📐 Formula

🎯 When to Use

⚙️ How It Works

📊 Interpreting the Result

⚠️ Limitations & Pitfalls

📚 References

When to Use

How It Works

Interpreting the Result

Limitations & Pitfalls

References