This Wells score calculator implements the Wells criteria for deep vein thrombosis (DVT): nine positive findings and one −2 discriminator, reported in both the three-tier (low/moderate/high) and two-tier (unlikely/likely) models.











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Pretest Probability: The Score Before the Scan

Part of our Health Calculators collection.

Worked Example

  • Post-surgical patient, whole leg swollen, calf +4 cm, deep tenderness: surgery (1) + entire leg (1) + calf ≥ 3 cm (1) + tenderness (1) = score 4 → DVT likely, three-tier HIGH (≈ 50%+) — straight to ultrasound
  • The −2 is the score's conscience: a clear alternative (cellulitis with a portal of entry, a ruptured Baker's cyst, a muscle tear) subtracts rather than merely failing to add — ticking tenderness and swelling (2 points) with a convincing alternative nets 0, low probability
  • Two-tier vs three-tier: same arithmetic, different routing — two-tier (≤1 / ≥2) pairs with D-dimer triage; three-tier preserves the moderate band many European pathways use

Score Discipline

  • Measure the calf difference with a tape at the same level both sides — “looks swollen” is not the ≥ 3 cm criterion.
  • Previously documented DVT (+1) belongs to the modified Wells used here; the 1997 original lacked it — both are in circulation, so cite which version a protocol uses.
  • D-dimer cannot clear a “likely” score: negative D-dimers in high-pretest patients still proceed to imaging.
  • Bilateral symptoms, pregnancy and upper-limb DVT sit outside the model's derivation — specialist pathways apply.

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Frequently Asked Questions

How is the Wells score for DVT calculated?

One point each for nine findings (active cancer, immobilization/paralysis, recent bedrest or surgery, deep tenderness, whole-leg swelling, calf swelling ≥ 3 cm, pitting edema, collateral veins, previously documented DVT), minus 2 if an alternative diagnosis is at least as likely. This calculator totals it and reports both standard interpretations.

What Wells score means DVT is likely?

In the two-tier model, ≥ 2 = “DVT likely” (proceed to ultrasound); ≤ 1 = “unlikely” (D-dimer triage). In the three-tier original, ≤ 0 is low (~3–5% prevalence), 1–2 moderate (~17%), ≥ 3 high (~50%+).

Why does an alternative diagnosis subtract 2 points?

It's the model's most influential item and its clinical conscience: Wells built it from the observation that experienced clinicians' “something else explains this better” judgment carried real discriminating power. A ruptured Baker's cyst or cellulitis genuinely makes DVT less probable, not merely unproven.

Can a negative D-dimer rule out DVT with a high Wells score?

No. D-dimer exclusion is validated for low/unlikely pretest probability. With a likely/high score, imaging proceeds regardless — a negative D-dimer in that group has an unacceptable miss rate. The score decides which test settles the question.

Is there a Wells score for pulmonary embolism too?

Yes — a related but distinct criteria set (clinical DVT signs +3, “PE is the top diagnosis” +3, heart rate > 100 +1.5, immobilization/surgery +1.5, prior DVT/PE +1.5, hemoptysis +1, malignancy +1), typically read as ≤ 4 / > 4 with D-dimer or CT pathways. This page implements the DVT version.

Is this Wells score calculator medical advice?

No — an educational implementation of a published score. Suspected DVT needs same-day clinical assessment.