From the Guidelines
The Wells criteria for Deep Vein Thrombosis (DVT) are a clinical prediction rule used to estimate the probability of DVT, and they include 9 clinical characteristics that are assigned a score, with a total score of ≥2 indicating a likely probability of DVT.
Clinical Characteristics and Scores
- Active cancer: 1 point
- Paralysis, paresis, or recent plaster immobilization of the lower extremities: 1 point
- Recently bedridden for ≥3 days, or major surgery within the previous 12 weeks requiring general or regional anesthesia: 1 point
- Localized tenderness along the distribution of the deep venous system: 1 point
- Entire leg swollen: 1 point
- Calf swelling at least 3 cm larger than the asymptomatic side: 1 point
- Pitting edema confined to the symptomatic leg: 1 point
- Collateral superficial veins (nonvaricose): 1 point
- Previously documented deep venous thrombosis: 1 point
- Alternative diagnosis at least as likely as deep venous thrombosis: -2 points As noted in the study published in Circulation in 2018 1, a score of ≥2 indicates that the probability of deep venous thrombosis is likely, while a score of <2 indicates that the probability of deep venous thrombosis is unlikely.
From the Research
Wells Criteria for Deep Vein Thrombosis (DVT)
The Wells criteria are a clinical prediction rule used to assess the pre-test probability of DVT. The criteria include:
- Active cancer (1 point)
- Paralysis, paresis, or recent plaster immobilization of the lower extremities (1 point)
- Recently bedridden for more than 3 days or major surgery within the last 12 weeks (1 point)
- Local tenderness along the distribution of the deep venous system (1 point)
- Entire leg swollen (1 point)
- Calf swelling at least 3 cm more than asymptomatic side (1 point)
- Pitting edema confined to the symptomatic leg (1 point)
- Collateral superficial veins (1 point)
- Alternative diagnosis is less likely than DVT (3 points)
Application of Wells Criteria
The Wells criteria have been studied in various settings, including outpatient and inpatient populations. Studies have shown that the Wells score can be useful in identifying patients at low risk of DVT 2, 3, 4. However, the performance of the Wells score in the inpatient setting has been found to be limited, with a higher failure rate and lower efficiency compared to the outpatient setting 5. In primary care settings, the Wells scale has been found to demonstrate a high degree of accuracy in assessing the probability of lower limb DVT 6.
Key Findings
- The Wells score can be used to stratify patients into low, moderate, and high risk categories for DVT 2, 3, 4.
- The score has been found to perform well in outpatient settings, but its performance in inpatient settings is limited 5.
- The Wells scale has been found to demonstrate a high degree of accuracy in primary care settings 6.
- A Wells score of <1 can reliably rule out the possibility of DVT in trauma patients 4.