Active malignancy within 6 months or palliative treatment
+1 pointsRecent immobilization or paralysis of the affected leg
+1 pointsProlonged bed rest or recent major surgery
+1 pointsTenderness along the deep venous system
+1 pointsSwelling of the entire affected leg
+1 pointsCalf swelling >3 cm compared to asymptomatic leg
+1 pointsPitting edema only in the symptomatic leg
+1 pointsPresence of collateral superficial veins
+1 pointsHistory of previous deep vein thrombosis
+1 pointsAlternative diagnosis equally or more likely than DVT
-2 pointsWells Score Interpretation
Clinical Management
- Low probability: D-dimer testing. If negative, DVT ruled out
- Moderate probability: D-dimer and/or imaging studies
- High probability: Consider immediate imaging, D-dimer may not be needed
- Always use clinical judgment in addition to the score
Wells Criteria for DVT (Deep Vein Thrombosis)
The Wells Criteria for DVT is a validated clinical prediction rule used to assess the probability of deep vein thrombosis in the lower extremities. This tool helps guide diagnostic testing and management decisions by stratifying patients into low, moderate, and high probability categories.
Wells Criteria Components
The Wells score is calculated by assigning points for each of the following criteria:
- Active cancer (1 point): Treatment within 6 months, palliative, or metastatic
- Paralysis/paresis/recent immobilization (1 point): Recent plaster immobilization of lower extremity
- Recent bed rest (1 point): Bedridden >3 days or major surgery within 12 weeks
- Localized tenderness (1 point): Along distribution of deep venous system
- Entire leg swelling (1 point): Swelling of the entire affected leg
- Calf swelling >3 cm (1 point): Compared to asymptomatic leg, measured 10 cm below tibial tuberosity
- Pitting edema (1 point): Confined to symptomatic leg
- Collateral superficial veins (1 point): Non-varicose collateral veins
- Previously documented DVT (1 point): History of previous deep vein thrombosis
- Alternative diagnosis (-2 points): Alternative diagnosis at least as likely as DVT
Score Interpretation
Low Probability (≤0 points) - 3% Prevalence
- Clinical significance: DVT unlikely
- Management: Consider D-dimer testing
- If D-dimer negative: DVT can be safely ruled out
- If D-dimer positive: Consider imaging studies
Moderate Probability (1-2 points) - 17% Prevalence
- Clinical significance: Moderate probability of DVT
- Management: Consider D-dimer testing and/or imaging studies
- Imaging options: Compression ultrasound, CT venography
- Follow-up: May require repeat testing
High Probability (≥3 points) - 75% Prevalence
- Clinical significance: High probability of DVT
- Management: Consider immediate imaging studies
- D-dimer role: May not be necessary in high-probability cases
- Treatment: Consider anticoagulation while awaiting results
Clinical Applications
Diagnostic Strategy
- Low probability + negative D-dimer: DVT ruled out (99% negative predictive value)
- Moderate probability: D-dimer testing, then imaging if positive
- High probability: Direct to imaging, consider empiric treatment
- Imaging options: Compression ultrasound (first choice), CT venography, MR venography
Management Considerations
- Anticoagulation: Consider in high-probability cases while awaiting imaging
- Compression stockings: May provide symptomatic relief
- Follow-up: Repeat testing may be needed in moderate probability cases
- Risk factors: Address underlying risk factors (immobility, cancer, etc.)
Important Considerations
Limitations
- Not validated for upper extremity DVT
- May not apply to pregnant patients
- Requires clinical judgment in addition to score
- Alternative diagnosis criterion is subjective
- May not capture all risk factors
Special Populations
- Pregnant patients: Modified approach may be needed
- Cancer patients: Higher baseline risk regardless of score
- Elderly patients: May have atypical presentations
- Recurrent DVT: Previous DVT increases risk
Clinical Pearls
- Always use clinical judgment in addition to the Wells score
- Consider patient's overall risk profile and comorbidities
- D-dimer testing is most useful in low-probability cases
- High-probability cases may benefit from immediate imaging
- Monitor for signs of pulmonary embolism in DVT patients
- Address underlying risk factors to prevent recurrence
- Consider alternative diagnoses that may mimic DVT
This calculator provides a validated method for assessing DVT probability, which helps guide appropriate diagnostic testing and management decisions. The Wells criteria are widely used in clinical practice and have been validated in multiple populations.
References
- 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.
- Wells PS, et al. Value of assessment of pretest probability of deep-vein thrombosis in clinical management. Lancet. 1997;350(9094):1795-1798.
- Kearon C, et al. Antithrombotic therapy for VTE disease: CHEST guideline and expert panel report. Chest. 2016;149(2):315-352.
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