Wells Score Calculator for DVT
The two-level Wells score for deep vein thrombosis, scored exactly as NICE tabulates it, with the DVT likely and unlikely pathways each result leads to.
Wells Score Calculator for DVT: with the default inputs, two-level dvt wells score is 0.
Treatment ongoing, within the last 6 months, or palliative.
Range −2 to 9.
- Clinical probability
- DVT unlikely (1 point or less)
- The pathway this leads to
- NICE: offer a D-dimer test with the result available within 4 hours. If D-dimer is positive, proceed to a proximal leg vein ultrasound scan; if it is negative, DVT is not likely — but discuss the signs and symptoms of DVT and when to seek further help.
- Features scored
- 0
Assumptions
- This is an estimate for education. It does not diagnose anything and does not replace clinical judgement.
- This is the two-level Wells score for deep vein thrombosis, not the Wells score for pulmonary embolism, which is a different instrument.
- Items and point values are those tabulated in NICE NG158, Table 1, adapted from Wells et al. (2003).
- The score is decision support that selects a diagnostic pathway; it does not diagnose or exclude DVT on its own.
- The pathways quoted are NICE's; local pathways differ.
- Six of the ten items are examination findings, so the score is only as good as the examination behind it.
| Clinical feature | Points | Scored |
|---|---|---|
| Active cancer | 1 | |
| Paralysis, paresis or recent plaster immobilisation of the lower extremities | 1 | |
| Recently bedridden for 3 days or more, or major surgery within 12 weeks requiring general or regional anaesthesia | 1 | |
| Localised tenderness along the distribution of the deep venous system | 1 | |
| Entire leg swollen | 1 | |
| Calf swelling at least 3 cm larger than the asymptomatic side | 1 | |
| Pitting oedema confined to the symptomatic leg | 1 | |
| Collateral superficial veins (non-varicose) | 1 | |
| Previously documented DVT | 1 | |
| An alternative diagnosis is at least as likely as DVT | -2 |
As tabulated in NICE NG158, Table 1, adapted from Wells et al. (2003). Two points or more is DVT likely; one point or less is DVT unlikely.
How this is worked out
The formula
Two-level DVT Wells score — one point for each feature, except the last:
Active cancer (treatment ongoing, within 6 months, or palliative) 1
Paralysis, paresis or recent plaster immobilisation of the lower extremities 1
Recently bedridden ≥3 days, or major surgery within 12 weeks under
general or regional anaesthesia 1
Localised tenderness along the distribution of the deep venous system 1
Entire leg swollen 1
Calf swelling at least 3 cm larger than the asymptomatic side 1
Pitting oedema confined to the symptomatic leg 1
Collateral superficial veins (non-varicose) 1
Previously documented DVT 1
An alternative diagnosis is at least as likely as DVT −2
2 points or more → DVT likely
1 point or less → DVT unlikelyOpen How it’s calculated above to see this worked through with your own numbers.
What you enter
- Active cancer (1 point)
- Treatment ongoing, within the last 6 months, or palliative.defaults to off
- Paralysis, paresis or recent plaster immobilisation of the lower extremities (1 point)
- Turn this on or off.defaults to off
- Recently bedridden for 3 days or more, or major surgery within 12 weeks requiring general or regional anaesthesia (1 point)
- Turn this on or off.defaults to off
- Localised tenderness along the distribution of the deep venous system (1 point)
- Turn this on or off.defaults to off
- Entire leg swollen (1 point)
- Turn this on or off.defaults to off
- Calf swelling at least 3 cm larger than the asymptomatic side (1 point)
- Turn this on or off.defaults to off
- Pitting oedema confined to the symptomatic leg (1 point)
- Turn this on or off.defaults to off
- Collateral superficial veins (non-varicose) (1 point)
- Turn this on or off.defaults to off
- Previously documented DVT (1 point)
- Turn this on or off.defaults to off
- An alternative diagnosis is at least as likely as DVT (−2 points)
- Turn this on or off.defaults to off
What you get back
- Two-level DVT Wells scoremain answer
- Range −2 to 9.
- Clinical probability
- The pathway this leads to
- Features scored
What this assumes
- This is an estimate for education. It does not diagnose anything and does not replace clinical judgement.
- This is the two-level Wells score for deep vein thrombosis, not the Wells score for pulmonary embolism, which is a different instrument.
- Items and point values are those tabulated in NICE NG158, Table 1, adapted from Wells et al. (2003).
- The score is decision support that selects a diagnostic pathway; it does not diagnose or exclude DVT on its own.
- The pathways quoted are NICE's; local pathways differ.
- Six of the ten items are examination findings, so the score is only as good as the examination behind it.
About this calculator
This is an estimate for education. It does not diagnose anything and does not replace clinical judgement.
What the score is for
The Wells score for deep vein thrombosis is a pre-test probability tool. Its job is not to say whether a patient has a clot — it is to decide which of two diagnostic pathways they should go down, because the value of a D-dimer test depends entirely on the probability you started with.
This page implements the two-level DVT version, scored exactly as NICE tabulates it in NG158 and adapted from Wells et al. (2003). Nine clinical features score one point each, and one item — an alternative diagnosis being at least as likely as DVT — subtracts two. Two points or more puts the patient in the DVT likely group; one point or less in the DVT unlikely group.
Note the name carefully. There is a separate Wells score for pulmonary embolism, with different items, different weights and a different threshold. The two are not interchangeable and mixing them up is a real error.
What each result leads to
DVT likely (2 or more). NICE: offer a proximal leg vein ultrasound scan, with the result available within 4 hours if possible, and a D-dimer if the scan is negative. If the scan cannot be obtained within 4 hours, offer a D-dimer, start interim therapeutic anticoagulation, and get the scan within 24 hours.
DVT unlikely (1 or less). NICE: offer a D-dimer with the result available within 4 hours. If it is positive, proceed to ultrasound. If it is negative, DVT is not likely — and the patient should still be told what the signs and symptoms of DVT are and when to seek help.
That last clause matters. "Unlikely" is a branch of a pathway, not a discharge diagnosis.
Where it stops being a calculation
Six of the ten items are examination findings. Calf circumference has to be measured, not eyeballed. Pitting oedema has to be confined to the symptomatic leg. Collateral veins have to be distinguished from varicose ones. And the −2 item asks whether an alternative diagnosis is at least as likely — a judgement that no scoring system can standardise, and which frequently decides which side of the threshold a patient lands on. That is why the score belongs to the clinician who examined the patient rather than to a form filled in afterwards.
The limits of the pathway
D-dimer rises in pregnancy, in cancer, after surgery, with infection and with age, which is why it is used to rule DVT out rather than to rule it in. Ultrasound of the proximal veins does not reliably see isolated calf vein thrombosis, which is part of why a negative initial scan with a positive D-dimer prompts a repeat rather than a discharge. And clinical decision rules describe populations: a patient whose story does not fit the rule is still a patient, and the score does not overrule the clinician who is worried.
Frequently asked questions
▸How is the two-level DVT Wells score calculated?
One point for each of nine clinical features, minus two if an alternative diagnosis is at least as likely as DVT. Two points or more is DVT likely; one point or less is DVT unlikely.
▸What happens if the Wells score says DVT is likely?
NICE recommends a proximal leg vein ultrasound within 4 hours where possible, with a D-dimer if the scan is negative. If the scan cannot be done in 4 hours, a D-dimer plus interim anticoagulation and a scan within 24 hours.
▸Does a low Wells score rule out DVT?
No. It puts the patient on the pathway that starts with a D-dimer. DVT is only considered unlikely when a low score is combined with a negative D-dimer, and even then the patient should be told when to seek help.
▸Is this the same as the Wells score for pulmonary embolism?
No. The PE score uses different items with different weights — clinical signs of DVT and an alternative diagnosis being less likely score 3 each — and a different threshold. Do not substitute one for the other.
▸Why does one item subtract points?
Because a plausible alternative explanation for a swollen leg — cellulitis, a ruptured Baker's cyst, chronic venous insufficiency — genuinely lowers the probability of DVT. It is also the most subjective item on the score and often decides the classification.
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