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Wells Score for DVT

Pre-test probability of deep vein thrombosis (2003 modified version).

For healthcare professionalsThrombosis & VTEv1.0.1

For healthcare professionals / clinical use. Not a self-diagnosis tool.

Your measurements

Active cancer (treatment ongoing, within 6 months, or palliative)
Paralysis, paresis or recent leg plaster cast
Bedridden ≥ 3 days, or major surgery within 12 weeks requiring general or regional anaesthesia
Localised tenderness along the deep veins
Entire leg swollen
Calf swelling ≥ 3 cm more than the other leg
Pitting oedema confined to the symptomatic leg
Collateral superficial (non-varicose) veins
Previously documented DVT
Alternative diagnosis at least as likely as DVT

Calculated on your device. Nothing is sent to a server.

Your result will appear here

Enter your measurements, then press Calculate.

Methodology

Wells DVT (Wells 2003)

1 point per criterion (9 items); −2 if an alternative diagnosis is at least as likely

Used with D-dimer: 'DVT unlikely' plus a negative D-dimer typically allows DVT to be excluded.

Who it is for
Adult outpatients with suspected lower-limb DVT.
Version
1.0.1

How this calculator works

Where the formula comes from

  • Wells and colleagues (1995) first tested a clinical model in 529 outpatients with suspected DVT at three centres; DVT was found in 85% of the high, 33% of the moderate and 5% of the low probability group.[1]
  • In 2003 a modified two-level model (DVT likely or unlikely) was tested in a randomised trial of 1,096 outpatients; DVT or pulmonary embolism was present in 15.7%.[2]
  • In that trial, DVT was ruled out without ultrasound in patients judged clinically unlikely with a negative D-dimer, and only 0.4% of patients in whom DVT had been ruled out had a confirmed event in the D-dimer group over three months.[2]

The inputs

  • One point each for active cancer, paralysis or recent leg plaster, being bedridden 3 days or more or recent major surgery, localised deep-vein tenderness, whole-leg swelling, calf swelling of 3 cm or more, pitting oedema confined to the symptomatic leg, collateral non-varicose superficial veins and previously documented DVT; 2 points are subtracted if an alternative diagnosis is at least as likely.[3]
  • A score of 2 or more means DVT likely and 1 or less means DVT unlikely.[3]

Where accuracy falls (published evidence)

  • In a 2015 study of 1,135 inpatients the Wells score discriminated only slightly better than chance, and the authors concluded it is not sufficient to rule out DVT in hospitalised patients.[4]

What guidelines say

  • NICE (NG158) recommends the two-level DVT Wells score to estimate clinical probability; it recommends proximal leg vein ultrasound when DVT is likely and a D-dimer test when DVT is unlikely.[3]

Sources

  1. Wells PS, Hirsh J, Anderson DR, et al. Accuracy of clinical assessment of deep-vein thrombosis. Lancet. 1995;345(8961):1326–1330. doi:10.1016/s0140-6736(95)92535-x
  2. 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
  3. National Institute for Health and Care Excellence. Venous thromboembolic diseases: diagnosis, management and thrombophilia testing (NG158). London: NICE; 2020 (updated 2023). https://www.nice.org.uk/guidance/ng158
  4. Silveira PC, Ip IK, Goldhaber SZ, Piazza G, Benson CB, Khorasani R. Performance of Wells score for deep vein thrombosis in the inpatient setting. JAMA Intern Med. 2015;175(7):1112–1117. doi:10.1001/jamainternmed.2015.1687

Compiled from the published sources above. Every statement was agreed independently by three AI research tools (Claude, ChatGPT, DeepSeek) and its source verified in PubMed or Crossref by the Hakeemly editorial team. Not reviewed by a doctor unless stated. Agreed on

Worked example: how to calculate wells DVT

Inputs

Active cancer (treatment ongoing, within 6 months, or palliative)
Yes
Localised tenderness along the deep veins
Yes
Calf swelling ≥ 3 cm more than the other leg
Yes

Result

Wells DVT score
3

2 or more: DVT likely

An illustration with sample values, worked out with the same method the tool above uses.

Limitations

  • Developed in outpatients; in hospitalised patients it performed only slightly better than chance (Silveira 2015).

References

  1. 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

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