Wells Score Calculator for DVT
Calculate the modified Wells score for suspected lower-extremity DVT, including exact paired calf measurements and current two-level interpretation.
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About
This Wells Score Calculator for DVT implements the modified 2003 Wells clinical prediction rule for an adult, nonpregnant outpatient with suspected lower-extremity deep-vein thrombosis. It adds nine one-point findings and subtracts two points when an alternative diagnosis is at least as likely. [2, 4]
The score estimates pretest probability within a diagnostic pathway. It does not diagnose or exclude DVT, calculate an individual disease probability, or choose D-dimer, ultrasonography, anticoagulation, referral, or treatment. [4, 5]
Interpretation
| Model | Score | Label | Boundary |
|---|---|---|---|
| Current NICE two-level | ≤1 | DVT unlikely | Pretest-probability label; not exclusion. |
| ≥2 | DVT likely | Pretest-probability label; not confirmation. | |
| Traditional three-level | ≤0 | Low | Historical model context. |
| 1–2 | Moderate | Historical model context. | |
| ≥3 | High | Historical model context. |
In the 1997 outpatient cohort, DVT prevalence was 3%, 17%, and 75% in the low, moderate, and high groups. These are historical population observations—not individual probabilities and not universal rates for another setting. [1]
How to use and interpret the Wells DVT score
Measure the calf criterion at the specified landmark
Compare the symptomatic and asymptomatic calves at the same level, 10 cm below the tibial tuberosity. A signed symptomatic-minus-asymptomatic difference of at least 3 cm adds one point. This calculator accepts paired cm or inch measurements and converts inches with the exact 2.54 cm/in factor; it never uses an absolute difference. If the chart already documents the criterion, choose the documented Yes/No mode instead. [2, 4]
The criterion assumes an asymptomatic comparison side. Bilateral swelling or inability to identify an asymptomatic side can limit straightforward application. Both measurements should use the same anatomical level, and software cannot verify the examination technique.
Current two-level diagnostic pathway context
NICE uses the two-level score within a wider pathway: DVT unlikely (≤1) generally enters a D-dimer-first branch, while DVT likely (≥2) generally enters a proximal-leg-vein ultrasound-first branch. NICE also advises considering an age-adjusted D-dimer threshold for people older than 50; this page does not accept a D-dimer value, assume assay units, or calculate its cutoff. Timing, interim actions, repeat imaging, and exceptions belong to the full current pathway. This page reports the score and does not order or authorize any next step. [4]
Outpatient evidence does not transfer automatically to inpatients
The modified rule was evaluated in outpatients with suspected lower-extremity DVT. In a 2015 inpatient study, observed proximal DVT prevalence was 5.9%, 9.5%, and 16.4% across low, moderate, and high groups, with area under the receiver operating characteristic curve 0.60. Do not use a low Wells DVT score alone to rule out DVT or alter management in hospitalized patients. The authors concluded inpatient stratification was not sufficient for either purpose, and these cohort results are not individual probabilities. [2, 6]
Pregnancy and upper-extremity thrombosis require separate pathways
NICE NG158 does not cover pregnant women, and the ASH diagnostic guideline also excludes pregnancy from its modeled recommendations. Suspected upper-extremity DVT uses different evidence and may use the separate Constans clinical decision rule; this calculator does not adapt Wells DVT to either setting. [4, 5]
Wells DVT, Wells PE, and PERC are different tasks
This page scores suspected lower-extremity DVT. Wells PE uses seven differently weighted criteria for suspected pulmonary embolism. PERC is an eight-item conditional rule-out tool only after low PE probability is already established. One result cannot be converted into another. [3, 5]
Why some Wells DVT calculators use different wording
Published and secondary versions vary in small timing and inequality details. This calculator intentionally implements the 2003 modified Wells DVT model as represented in the current NICE two-level table: bedridden for 3 days or more, qualifying major surgery within 12 weeks, and calf swelling at least 3 cm. It does not calculate several subtly different variants. [2, 4]
Previous DVT is a scored item, not an automatic exclusion
Previously documented DVT adds one point in the modified model. That does not make every suspected recurrence equivalent to a first event: recurrent-DVT evaluation can require comparison with prior imaging and other diagnostic context, which this calculator does not collect or interpret. [2, 5]
Important limits
Clinical pretest probability alone cannot diagnose or exclude DVT. Symptoms, alternative diagnoses, care setting, prior thrombosis, anticoagulation, test availability, laboratory assay, and imaging quality affect the appropriate pathway. Urgent or unstable presentations require direct clinical assessment rather than reliance on this page. [4, 5]
References
- Wells PS, et al. Value of assessment of pretest probability of deep-vein thrombosis in clinical management. Lancet. 1997;350(9094):1795–1798. PMID 9428249. DOI 10.1016/S0140-6736(97)08140-3.
- Wells PS, et al. Evaluation of D-dimer in the diagnosis of suspected deep-vein thrombosis. N Engl J Med. 2003;349(13):1227–1235. PMID 14507948. DOI 10.1056/NEJMoa023153.
- Wells PS, Owen C, Doucette S, Fergusson D, Tran H. Does this patient have deep vein thrombosis? JAMA. 2006;295(2):199–207. PMID 16403932. DOI 10.1001/jama.295.2.199.
- National Institute for Health and Care Excellence. Venous thromboembolic diseases: diagnosis, management and thrombophilia testing (NG158), recommendations 1.1.2–1.1.8 and two-level DVT Wells table. Published 2020; updated 2023; reviewed May 1, 2026.
- Lim W, et al. American Society of Hematology 2018 guidelines for management of venous thromboembolism: diagnosis of venous thromboembolism. Blood Adv. 2018;2(22):3226–3256. PMID 30482764. DOI 10.1182/bloodadvances.2018024828.
- Silveira PC, et al. Performance of Wells Score for Deep Vein Thrombosis in the Inpatient Setting. JAMA Intern Med. 2015;175(7):1112–1117. PMID 25985219. DOI 10.1001/jamainternmed.2015.1687.
FAQ
It adds ten explicitly assessed findings from the modified Wells clinical prediction rule for suspected lower-extremity DVT. Nine findings add 1 point each and an alternative diagnosis at least as likely as DVT subtracts 2 points. The result estimates pretest probability within a diagnostic pathway; it does not diagnose or exclude DVT.
The criteria cover active cancer; lower-extremity paralysis, paresis, or plaster immobilization; bedridden status for at least 3 days or qualifying major surgery within 12 weeks; deep-venous tenderness; entire-leg swelling; calf swelling at least 3 cm; symptomatic-leg pitting edema; nonvaricose collateral superficial veins; previous DVT; and an alternative diagnosis at least as likely as DVT.
Measure the symptomatic and asymptomatic calves at the same level, 10 cm below the tibial tuberosity. Subtract the asymptomatic-side circumference from the symptomatic side. A signed difference of at least 3 cm adds 1 point; exactly 3 cm qualifies. This calculator can make the exact comparison from paired cm or inch measurements.
The current NICE table adapted from Wells 2003 says calf swelling at least 3 cm larger than the asymptomatic side, so exactly 3 cm meets this implementation's criterion. Some secondary calculators use greater-than wording; QuickMedCalc does not blend those variants into the primary model.
In the current NICE two-level model, a score of 2 or more is DVT likely and a score of 1 or less is DVT unlikely. These are pretest-probability labels used within a testing pathway, not confirmation or exclusion of DVT and not individual disease probabilities.
Sources: [4]
The traditional three-level model uses 0 or less for low, 1–2 for moderate, and 3 or more for high pretest probability. The page shows this only as secondary historical model context; it does not replace the current two-level result or turn historical cohort rates into individual probabilities.
No. NICE places the two-level score inside a broader pathway that generally uses a D-dimer-first branch for DVT unlikely and a proximal-leg-vein ultrasound-first branch for DVT likely. A score alone neither diagnoses nor excludes DVT. The full pathway controls timing, exceptions, assay use, repeat testing, and interim actions; this calculator only reports the score.
This implementation is scoped to the adult nonpregnant outpatient suspected-lower-extremity-DVT context. A 2015 inpatient study found limited discrimination and concluded the score was not sufficient to rule out DVT or guide inpatient management. Its observed group rates are population findings, not individual probabilities.
Related Calculators
Wells PE
Calculate the seven-criterion Wells score for pulmonary embolism with modified two-level and standard three-level classifications.
PERC Rule
Check all eight PERC criteria for a low-probability adult suspected-PE assessment, with exact age, pulse, room-air oxygen, history, and examination boundaries.
Disclaimer
Educational and informational reference only. Not intended to replace professional medical advice, diagnosis, treatment, or independent verification.