How it's calculated
Each criterion scores 1 point, except an equally-or-more-likely alternative diagnosis, which subtracts 2 points. A total score of ≥2 classifies DVT as "likely"; below 2 classifies it as "unlikely" (two-tier Wells model).
Two-tier interpretation
| Score | Category | Suggested next step |
|---|---|---|
| < 2 | DVT unlikely | D-dimer — if negative, DVT is effectively excluded |
| ≥ 2 | DVT likely | Compression ultrasound |
Clinical use
- The Wells DVT score is designed to be combined with a D-dimer test: a low pre-test probability plus a negative D-dimer reliably excludes DVT without imaging.
- In the "likely" category, D-dimer is not useful for exclusion — proceed directly to compression ultrasound regardless of D-dimer result.
- The score was validated in outpatients with suspected first DVT; its performance is less established in special populations such as pregnancy, active cancer, or suspected recurrent DVT.
- A three-tier version (low/moderate/high) also exists in the original literature, but the two-tier likely/unlikely dichotomy shown here is the version most widely used in current practice.
Frequently asked questions
What is the Wells DVT score used for?
It estimates the pre-test probability that a patient's leg symptoms are due to deep vein thrombosis, guiding whether D-dimer testing alone can exclude DVT or whether ultrasound is needed.
What does a Wells DVT score of 2 or more mean?
It classifies the patient as "DVT likely" — in this group, a D-dimer test isn't reliable for ruling out DVT, so compression ultrasound is the recommended next step regardless of D-dimer result.
Can a negative D-dimer rule out DVT on its own?
Only when combined with a low pre-test probability (Wells score <2, "DVT unlikely") — a negative D-dimer in that group reliably excludes DVT without needing an ultrasound.
Does the Wells score work for pregnant patients?
Its validation was in non-pregnant outpatients with suspected first DVT — special populations like pregnancy or suspected recurrent DVT may need different or additional diagnostic pathways.
References
- Wells PS, et al. Value of assessment of pretest probability of deep-vein thrombosis in clinical management. Lancet. 1997;350:1795-1798.
- Wells PS, et al. Evaluation of D-dimer in the diagnosis of suspected deep-vein thrombosis. N Engl J Med. 2003;349:1227-1235.
- National Institute for Health and Care Excellence (NICE). Venous thromboembolic diseases: diagnosis, management and thrombophilia testing.