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BackTable / VI / Tool
Wells' Criteria for DVT
The Wells' criteria DVT calculator is an evidence-based clinical decision-making tool designed to assess the probability of deep vein thrombosis (DVT) in patients presenting with symptoms that may suggest this condition. Deep vein thrombosis is the formation of a blood clot in the deep veins, typically in the legs or pelvis, which can potentially lead to serious complications such as a pulmonary embolism if the clot dislodges and travels to the lungs.
This calculator employs the Wells' criteria for DVT, which is a set of clinical parameters developed by Dr. Phil Wells and his colleagues in 1997. The criteria set below is the most widely validated criteria and is based on Wells 2003 and uses the three-tier model for risk analysis. It is widely used by healthcare professionals to classify patients into different risk categories based on their likelihood of having a DVT.
To utilize the Wells' score DVT calculator, clinicians enter patient-specific data, such as active cancer, recent immobilization, localized tenderness along the deep venous system, and leg swelling. The calculator assigns points to each criterion, and the total score determines the patient's risk category: low, moderate, or high probability of DVT.
Based on the risk category, the clinician may proceed with further diagnostic testing, such as D-dimer testing or imaging studies like venous duplex ultrasonography, to confirm or exclude the presence of a DVT. The Wells' criteria DVT calculator is a valuable tool that helps facilitate the diagnostic process, enabling quicker, more informed decision-making and potentially improving patient outcomes.
Wells' Criteria for DVT
Active Cancer
Treatment or palliation within 6 months
Bedridden recently >3 days or major surgery within 12 weeks
Calf swelling >3cm compared to the other leg
Measured 10 cm below tibial tuberosity
Collateral (nonvaricose) superficial veins present
Entire leg swollen
Localized tenderness along the deep venous system
Pitting edema, confined to symptomatic leg
Paralysis, paresis, or recent plaster immobilization of the lower extremity
Previously documented DVT
Alternative diagnosis to DVT as likely or more likely
Value
Alternative diagnosis to DVT as likely or more likely
How to Use the Calculator and Interpret Results
To use the calculator, check all clinical features that apply to the patient. Each selection adds to the total score and the calculator will automatically display the total Wells score and corresponding DVT risk category.
• Active Cancer: Treatment or palliation within 6 months
• Bedridden recently >3 days or major surgery within 12 weeks
• Calf swelling >3cm compared to the other leg: Measured 10 cm below tibial tuberosity
• Collateral (nonvaricose) superficial veins present
• Entire leg swollen
• Localized tenderness along the deep venous system
• Pitting edema, confined to symptomatic leg
• Paralysis, paresis, or recent plaster immobilization of the lower extremity
• Previously documented DVT
• Alternative diagnosis to DVT as likely or more likely, subtract 2 points.
The calculator will automatically display the total Wells score and corresponding DVT risk category:
• Low Risk (≤0 points): ~5% chance of DVT. D-dimer testing can rule out DVT without imaging if negative.
• Moderate Risk (1–2 points): ~17% chance of DVT. D-dimer or imaging depending on clinical context.
• High Risk (≥3 points): >50% chance of DVT. Recommend immediate imaging.
Clinical Considerations and Best Practices
The Wells Criteria is particularly helpful in emergency and outpatient settings where clinicians must quickly determine the necessity of imaging. It’s most effective when paired with D-dimer testing, especially for patients at low to moderate risk. A low Wells score and negative D-dimer test strongly suggest that DVT is unlikely.
Keep in mind that this DVT risk calculator is less reliable in hospitalized or post-operative patients and should always be used alongside clinical judgment. When in doubt, reevaluate your patient’s symptoms and consider repeat testing if new signs arise.
Learn more on the BackTable VI Podcast
BackTable is a knowledge resource for physicians by physicians. Get practical advice on the Wells' Criteria for DVT and how to build your practice by listening to the BackTable VI Podcast, reading exclusing BackTable Articles, and following the work of our Contributors.
References
[1] Singh, B., et al. "Clinical decision rules in the initial evaluation of deep vein thrombosis in primary care: a systematic review." BMJ Open, 2016.
[2] Goodacre, S., et al. "Systematic review and meta-analysis of the diagnostic accuracy of clinical prediction rules and D-dimer for suspected deep vein thrombosis." Journal of Thrombosis and Haemostasis, 2015.
[3] Wells, P. S., et al. "Use of a clinical model for safe management of patients with suspected pulmonary embolism." Annals of Internal Medicine, 2003.
Disclaimer: The Materials available on BackTable.com are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
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