Wells DVT score: how the points are calculated

The Wells score for deep vein thrombosis (DVT) adds 1 point for each of nine findings, such as active cancer, calf swelling more than 3 cm compared with the other leg, or a previous DVT, and subtracts 2 points if another explanation is at least as likely as DVT. The total runs from −2 to 9. Active cancer plus calf swelling, with nothing else, scores 2.

Not a medical device. Not a diagnosis or dosing recommendation.

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Infection and VTE calculators
Wells PS et al. · 2003
The Wells DVT formula
Worked examples
Wells DVT points table
Frequently asked questions

What is the Wells DVT score?

The Wells DVT score is a clinical model for suspected deep vein thrombosis in the leg, from Philip S. Wells and colleagues. Magent's calculator follows the version in their 2003 New England Journal of Medicine paper, which lists nine findings worth 1 point each and one item that takes 2 points away.

It's also called the Wells criteria for DVT or the Wells deep vein thrombosis score.

This page explains the arithmetic. It doesn't give a cutoff, it doesn't sort totals into probability groups, and it doesn't say what a score means for a particular person.

The Wells DVT formula

Wells DVT = (+1 for each of 9 findings present)
          − 2 if an alternative explanation is at least as likely as DVT
range = −2 to 9

Exact expression the calculator uses:

Wells DVT = +1 each of 9 findings; −2 if alternative_diagnosis_as_likely

What each part means

Input	Finding	Points
`active_cancer`	Active cancer (currently treated, treated within the last 6 months, or palliative care)	+1
`paralysis_or_cast`	Paralysis, paresis, or recent plaster immobilization of the legs	+1
`bedridden_or_surgery`	Recently bedridden 3 days or more, or major surgery within 12 weeks	+1
`tenderness`	Localized tenderness along the deep veins	+1
`entire_leg_swollen`	The entire leg is swollen	+1
`calf_swelling_gt_3cm`	Calf swelling more than 3 cm compared with the other leg	+1
`pitting_edema`	Pitting edema in the symptomatic leg alone	+1
`collateral_veins`	Collateral superficial veins (not varicose veins)	+1
`previous_dvt`	A previously documented DVT	+1
`alternative_diagnosis_as_likely`	Another explanation is at least as likely as DVT	−2

How the score works

Go through the nine findings. Each one present adds 1 point.
Ask about another explanation. If another explanation is at least as likely as DVT, subtract 2.
Add it up. The total can be as low as −2 (no findings, another explanation as likely) or as high as 9 (all nine findings, no other explanation as likely).

Yes/no inputs

Every input is true or false. The record says the findings come from the person using the calculator; Magent doesn't examine the leg. The calculator returns the total, the maximum of 9, and a line for each item. It also returns group labels for the total; this page doesn't describe them.

Worked examples

These use Magent's own expected values for the calculator.

Example 1: no findings

None of the nine findings; no alternative explanation as likely.
Score = 0.

Example 2: active cancer and calf swelling

Active cancer → +1.
Calf swelling more than 3 cm → +1.
Score = 2.

Example 3: four findings

Active cancer → +1; paralysis or cast → +1.
Bedridden or recent surgery → +1; tenderness along the deep veins → +1.
Score = 4.

Example 4: another explanation is as likely

Active cancer → +1; calf swelling → +1.
Another explanation at least as likely → −2.
Score = 1 + 1 − 2 = 0.

Wells DVT points table

Item	Points if present
Each of the nine findings	+1
Another explanation at least as likely	−2
Lowest possible total	−2
Highest possible total	9

Wells DVT reference values

These are Magent's expected values for the calculator. No findings scores 0. Active cancer with calf swelling scores 2. Active cancer, paralysis or a cast, being bedridden or recent surgery, and tenderness score 4. Active cancer with calf swelling scores 0 when another explanation is at least as likely.

History of the Wells DVT score

The calculator cites Philip S. Wells, David R. Anderson, Marc Rodger and colleagues, Evaluation of D-dimer in the diagnosis of suspected deep-vein thrombosis, New England Journal of Medicine 2003 (volume 349, issue 13, pages 1227–1235).

The abstract describes outpatients with suspected DVT in the leg. Physicians used a clinical model to evaluate each patient and placed them in one of two groups. The trial randomly assigned 530 patients to one testing approach and 566 to another, so 1,096 in all.

When it's used

The 2003 abstract describes the clinical model being used by physicians for outpatients with suspected lower-extremity DVT.

Where it's used

The 2003 trial enrolled outpatients. The record describes the calculator as doing the published Wells DVT arithmetic from yes/no findings.

Who uses it

In the 2003 paper, physicians assessed the patients. With Magent's calculator, the person using it supplies each finding.

Limits of the calculation

It adds up yes/no findings. It doesn't diagnose or rule out a DVT.
The "alternative explanation" item subtracts 2; it can take the total below zero.
Findings come from the user. Nothing is inferred from notes.
This page doesn't say what to do with a score.

Clinical decisions belong to a qualified clinician who knows the patient.

Wells PE is a separate score for suspected pulmonary embolism. It uses seven weighted items, so its total can include halves.

Glossary

Deep vein thrombosis (DVT): a blood clot in a deep vein, usually in the leg.
Paresis: partial weakness of a limb.
Pitting edema: swelling that keeps a dent after it's pressed.
Collateral superficial veins: surface veins that become visible as blood finds another route.
Palliative: care aimed at comfort rather than cure.

Common mistakes

Forgetting the −2. If another explanation is at least as likely, subtract 2.
Measuring calf swelling on one leg alone. It's compared with the other leg, and it has to be more than 3 cm.
Counting varicose veins. The item is for collateral veins that aren't varicose.
Mixing up the DVT and PE scores. They have different items and weights.

Source

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. DOI: 10.1056/NEJMoa023153

Frequently asked questions

How do you calculate the Wells DVT score?

Add 1 point for each of nine findings present, then subtract 2 if another explanation is at least as likely as DVT. The total is −2 to 9.

What Wells score means DVT is likely?

This page doesn't give a cutoff or sort scores into groups. It adds up the points; what a score means depends on the person and the clinical context.

Can the Wells DVT score be negative?

Yes. With one finding or none and another explanation as likely, the total drops below zero. The lowest is −2.

What is the highest Wells DVT score?

9, with all nine findings and no alternative explanation as likely.

Does the entire leg being swollen count separately from calf swelling?

Yes. They're two separate findings, each worth 1 point. A swollen leg can score both if the calf on that side is also more than 3 cm larger than the other calf.

How many points is active cancer?

1 point, the same as each of the other eight findings. In the Wells DVT score, the one item with a different weight is the alternative explanation, which takes away 2.

Does a previous DVT count?

Yes. A previously documented DVT adds 1 point.

Who developed the Wells DVT score?

Philip S. Wells and colleagues. Magent's calculator cites their 2003 New England Journal of Medicine paper.