liminfoWells Score Calculator
Free web tool: Wells Score Calculator
Wells Score
0
3-Level Risk
Low
~5%
2-Level Risk
DVT Unlikely
~6%
Wells criteria for DVT. Clinical reference only.
About Wells Score Calculator
The Wells Score Calculator implements the Wells Criteria for DVT (Deep Vein Thrombosis) — a validated clinical decision rule developed by Dr. Philip Wells to estimate the pre-test probability of DVT in patients presenting with leg symptoms. The tool presents all 10 Wells criteria as checkboxes, each assigned a point value (+1 per positive finding, −2 if an alternative diagnosis is at least as likely). Checking or unchecking criteria automatically updates the total Wells Score and the corresponding risk classification.
The calculator provides two risk stratification systems simultaneously: the 3-level model (Low: score ≤0, ~5% DVT probability; Moderate: score 1–2, ~17%; High: score ≥3, ~53%) and the 2-level model (DVT Unlikely: score <2, ~6%; DVT Likely: score ≥2, ~28%). The 2-level model is more commonly used in modern clinical practice, particularly alongside D-dimer testing — a negative D-dimer in the "DVT Unlikely" group effectively rules out DVT without requiring imaging.
The Wells Score is used by emergency physicians, internists, primary care doctors, and medical students as part of the structured clinical assessment for suspected DVT. It is not a standalone diagnostic test but a pre-test probability tool that guides the next step in the diagnostic algorithm — typically D-dimer testing for low/moderate probability and venous duplex ultrasound for higher probability cases. This tool is for clinical reference and educational purposes only.
Key Features
- All 10 Wells DVT criteria presented as interactive checkboxes with point values shown (+1 or -2)
- Real-time Wells Score total that updates instantly as criteria are checked or unchecked
- Both 3-level risk stratification (Low/Moderate/High) and 2-level model (Likely/Unlikely) displayed simultaneously
- Estimated DVT probability percentages for each risk category (~5%, ~17%, ~53% for 3-level; ~6%, ~28% for 2-level)
- Color-coded risk indicators (green for low, yellow for moderate, red for high) for quick visual reference
- Includes the negative scoring criterion (−2 for alternative diagnosis at least as likely as DVT)
- Clinical disclaimer note reminding users this is a reference tool, not a substitute for professional judgment
- 100% client-side processing — patient data never leaves the browser, maintaining privacy
Frequently Asked Questions
What is the Wells Score for DVT?
The Wells Score (or Wells Criteria) is a validated clinical prediction rule used to estimate the pre-test probability that a patient has deep vein thrombosis (DVT). It was developed by Dr. Philip Wells and colleagues and scores 10 clinical findings, with each positive criterion adding 1 point and a compensating factor subtracting 2 points if an alternative diagnosis is more likely. The total score classifies patients into Low, Moderate, or High risk categories.
What are the 10 Wells DVT criteria?
The 10 criteria are: (1) Active cancer treated within 6 months (+1); (2) Paralysis, paresis, or recent leg immobilization (+1); (3) Recently bedridden >3 days or major surgery within 12 weeks (+1); (4) Localized tenderness along the deep venous system (+1); (5) Entire leg swollen (+1); (6) Calf swelling >3 cm vs asymptomatic leg (+1); (7) Pitting edema confined to the symptomatic leg (+1); (8) Collateral superficial veins (non-varicose) (+1); (9) Previously documented DVT (+1); (10) Alternative diagnosis at least as likely as DVT (−2).
How is the Wells Score interpreted?
In the 3-level model: score ≤0 = Low risk (~5% DVT probability), score 1–2 = Moderate risk (~17%), score ≥3 = High risk (~53%). In the widely used 2-level model: score <2 = DVT Unlikely (~6% probability), score ≥2 = DVT Likely (~28%). The 2-level model is often preferred because a negative D-dimer in the "DVT Unlikely" group can effectively exclude DVT without ultrasound imaging.
What is D-dimer and how does it relate to the Wells Score?
D-dimer is a blood test that measures fibrin degradation products released when a clot breaks down. It is very sensitive but not specific — elevated in many conditions. In clinical practice, the Wells Score and D-dimer are used together: if a patient scores <2 (DVT Unlikely) AND has a negative D-dimer (<500 ng/mL), DVT can be confidently excluded without imaging. If D-dimer is elevated, or if the Wells Score is ≥2, venous duplex ultrasound is needed.
Why does "alternative diagnosis at least as likely" subtract 2 points?
The −2 criterion accounts for clinical situations where another diagnosis (such as a muscle strain, Baker's cyst, cellulitis, or superficial thrombophlebitis) is at least as plausible as DVT. Subtracting 2 points reflects the importance of clinical gestalt in lowering pre-test probability — if the clinician thinks another diagnosis is equally or more likely, the overall probability of DVT is meaningfully reduced.
What DVT risk does a Wells Score of 0 indicate?
A Wells Score of 0 or below places the patient in the Low risk category with approximately 5% estimated DVT probability. Combined with a negative D-dimer test, this can effectively rule out DVT in most clinical settings without requiring venous duplex ultrasound, reducing unnecessary imaging. However, clinical judgment should always override a scoring system when there is strong clinical suspicion.
Is this calculator appropriate for use in patients with suspected PE?
No. This tool calculates the Wells Score specifically for DVT, not for pulmonary embolism (PE). There is a separate Wells Score for PE (Wells PE Criteria) that uses different clinical variables and cutoffs. If you are assessing pre-test probability for PE, you need to use the Wells PE Score or the Geneva Score, not the DVT Wells Score.
Can this tool be used for clinical decision-making?
This tool is intended for clinical reference and educational purposes only. The Wells Score is a validated decision-support tool, but it must be applied by a qualified healthcare professional in the context of a full clinical assessment. Scores alone do not diagnose or exclude DVT. Always integrate the score with clinical history, physical exam findings, and relevant laboratory and imaging results.