Wells Score Calculator (DVT) Formula

Understand the math behind the wells score calculator (dvt). Each variable explained with a worked example.

Formulas Used

Wells Score

wells_total = active_cancer + paralysis + bedridden + tenderness + leg_swelling + calf_difference + pitting_edema + collateral_veins + alternative_diagnosis

Maximum Possible Score

risk_category = 8

Variables

Variable	Description	Default
`active_cancer`	Active Cancer?	0
`paralysis`	Paralysis/Immobilization of Leg?	0
`bedridden`	Bedridden >3 days or Major Surgery <12 wks?	0
`tenderness`	Tenderness Along Deep Vein?	0
`leg_swelling`	Entire Leg Swollen?	0
`calf_difference`	Calf >3 cm Larger Than Other?	0
`pitting_edema`	Pitting Edema in Symptomatic Leg?	0
`collateral_veins`	Collateral Superficial Veins?	0
`alternative_diagnosis`	Alternative Diagnosis as Likely?	0

How It Works

Wells Score for DVT

The Wells score estimates the pre-test probability of deep vein thrombosis.

Scoring Criteria

Each criterion scores +1 point, except "alternative diagnosis as likely" which scores -2.

Risk Categories

ScoreProbabilityDVT Prevalence 0 or lessLow~5% 1-2Moderate~17% 3+High~53%

Patients with low probability and negative D-dimer can safely avoid imaging.

Worked Example

A patient with active cancer, bedridden >3 days, and calf swelling.

active_cancer = 1paralysis = 0bedridden = 1tenderness = 0leg_swelling = 0calf_difference = 1pitting_edema = 0collateral_veins = 0alternative_diagnosis = 0

01Active cancer = +1
02Bedridden >3 days = +1
03Calf >3 cm larger = +1
04Total = 3 (High probability)

Frequently Asked Questions

What is the Wells score?

The Wells score is a clinical decision tool that estimates the probability of DVT based on signs, symptoms, and risk factors. It was developed by Dr. Philip Wells.

What happens after calculating the Wells score?

Low-probability patients get a D-dimer blood test. If negative, DVT is ruled out. Moderate and high-probability patients typically get an ultrasound.

Can I use this to diagnose DVT myself?

No. The Wells score is a clinical tool for healthcare providers. If you suspect a blood clot, seek immediate medical attention. Symptoms include leg pain, swelling, warmth, and redness.

Ready to run the numbers?

Open Wells Score Calculator (DVT)