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Wells Score for DVT Calculator

Calculate the Wells score for deep vein thrombosis (DVT) probability assessment using clinical criteria.

About this calculator

Developed by Philip Wells and colleagues and first published in The Lancet in 1997, this clinical prediction rule scores nine findings associated with DVT -- active cancer, paralysis or recent immobilization, being bedridden or post-surgical, localized tenderness, leg or calf swelling, pitting edema, collateral veins, and prior DVT -- each worth +1 point, and then subtracts 2 points if an alternative diagnosis is judged at least as likely as DVT. That -2 term is the only double-weighted criterion in the score, deliberately built to pull the total down harder than any single positive finding can push it up, on the reasoning that a clinician's judgment that something else better explains the presentation should carry outsized weight.

The resulting score sorts patients into three pretest-probability bands: high (score 3 or more, roughly 75% prevalence of DVT in the original derivation cohort), moderate (score 1-2, roughly 17%), and low (score 0 or below, roughly 3%). Wells is meant to be paired with a D-dimer test, not used alone -- a low-probability score combined with a negative D-dimer is generally considered sufficient to rule out DVT without imaging, while moderate or high scores, or any positive D-dimer, typically prompt compression ultrasound.

Inputs

Results

Wells Score

0pts

Risk Category

1(1=Low, 2=Moderate, 3=High)

DVT Prevalence3%

Figures current as of 1997. Source: Wells PS, Anderson DR, Bormanis J, et al. Value of assessment of pretest probability of deep-vein thrombosis in clinical management. Lancet. 1997;350(9094):1795-1798.

How to Use This Calculator
  1. Select Yes or No for each Wells DVT criterion (active cancer, paralysis, bedridden, local tenderness, etc.).
  2. Review Wells DVT Score and pre-test probability category (low, moderate, high).
  3. Low probability score with negative D-dimer effectively rules out DVT without ultrasound.

What each input means

Active Cancer
Treatment within 6 months or palliative (+1 point).
Paralysis/Paresis/Immobilization
Recent paralysis, paresis, or plaster cast of lower extremity (+1 point).
Bedridden >3 Days / Surgery <12 Weeks
Bedridden for >3 days or major surgery within 12 weeks (+1 point).
Localized Tenderness
Tenderness along deep venous system (+1 point).
Entire Leg Swollen
Entire leg is swollen (+1 point).
Calf Swelling >3 cm
Calf swelling >3 cm compared to asymptomatic leg (+1 point).
Pitting Edema
Pitting edema confined to symptomatic leg (+1 point).
Collateral Superficial Veins
Non-varicose collateral superficial veins (+1 point).
Previously Documented DVT
Previously documented DVT (+1 point).
Alternative Diagnosis Likely
Alternative diagnosis at least as likely as DVT (-2 points).

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Active Cancer = 0, Paralysis/Paresis/Immobilization = 0, Bedridden >3 Days / Surgery <12 Weeks = 0, Localized Tenderness = 0 = 10 input(s) provided
  2. Calculate Wells Score
    Wells Score
    0 = 0
  3. Calculate Risk Category
    Risk Category
    1 = 1
  4. Calculate DVT Prevalence
    DVT Prevalence
    3 = 3%

Figures and sources

Engine last updated . Checked against 3 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.

Frequently Asked Questions

Why is the alternative-diagnosis criterion worth -2 points instead of -1?

It's the only criterion in the Wells DVT score weighted more heavily than the others -- every positive finding (cancer, immobilization, swelling, and so on) adds exactly 1 point, but a clinician judging that another diagnosis is at least as likely as DVT subtracts 2. That makes it the single most influential item in the score: no combination of the nine positive findings can outweigh a confident alternative diagnosis the way one positive finding could be offset by another.

What DVT probability does a Wells score of 3 or higher correspond to?

A score of 3 or more places a patient in the "high probability" category, which corresponded to roughly 75% prevalence of confirmed DVT in the original derivation study. That's a strong enough pretest probability that a negative D-dimer alone is generally not considered sufficient to rule out DVT in this group -- compression ultrasound is typically still needed.

Can a low Wells score alone rule out a DVT?

Not by itself. A low-probability score (0 or below, roughly 3% prevalence in the original study) is meant to be combined with a D-dimer test -- when both the score is low and the D-dimer is negative, DVT is generally considered effectively ruled out without needing an ultrasound. The score alone, without a D-dimer, isn't treated as sufficient to stop the workup.

Does the Wells DVT score use the same criteria as the Wells score for PE?

No -- they're related but separate tools developed for different conditions. The DVT version scores leg-specific findings like calf swelling, pitting edema, and collateral veins, while the pulmonary embolism version scores different criteria such as heart rate, immobilization, and hemoptysis. A calculator or chart labeled simply "Wells score" should always specify which condition it's scoring.

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