From the Guidelines
The Wells' score for Deep Vein Thrombosis (DVT) probability assessment is a clinical prediction rule that considers nine criteria, with a score of ≥2 indicating a likely probability of DVT and a score of <2 indicating an unlikely probability. For DVT assessment, the Wells score considers the following criteria:
- Active cancer (treatment within 6 months or palliative) [1 point, 1]
- Paralysis, paresis, or recent plaster immobilization of the lower extremities [1 point, 1]
- Recently bedridden for ≥3 days, or major surgery within the previous 12 weeks requiring general or regional anesthesia [1 point, 1]
- Localized tenderness along the distribution of the deep venous system [1 point, 1]
- Entire leg swollen [1 point, 1]
- Calf swelling at least 3 cm larger than the asymptomatic side [1 point, 1]
- Pitting edema confined to the symptomatic leg [1 point, 1]
- Collateral superficial veins (nonvaricose) [1 point, 1]
- Previously documented deep venous thrombosis [1 point, 1]
- Alternative diagnosis at least as likely as deep venous thrombosis [-2 points, 1] The Wells score helps clinicians stratify patients and guide further diagnostic testing, such as D-dimer tests or imaging studies, as noted in the American College of Chest Physicians evidence-based clinical practice guidelines 1. The criteria and scoring system are based on the most recent and highest quality study available, which provides a comprehensive evaluation of suspected venous thromboembolism 1. It's essential to use the Wells score in conjunction with clinical judgment and other diagnostic methods for a comprehensive evaluation of suspected venous thromboembolism 1.
From the Research
Overview of the Wells' Score
The Wells' score is a widely used prediction rule for pre-test probability assessment of deep vein thrombosis (DVT) 2, 3, 4, 5. It is used to determine the likelihood of DVT in patients with suspected symptoms.
Components of the Wells' Score
The original Wells score consists of nine components, which include:
- Active cancer
- Paralysis or recent immobilization of the lower extremities
- Recently bedridden for more than 3 days
- Local tenderness along the distribution of the deep venous system
- Entire leg swollen
- Calf swelling of more than 3 cm compared to the asymptomatic leg
- Pitting edema
- Collateral superficial veins
- Alternative diagnosis is less likely than DVT
Calculation of the Wells' Score
Each component is assigned a score, and the total score is calculated to determine the pre-test probability of DVT 4. A higher score indicates a higher probability of DVT.
Interpretation of the Wells' Score
The Wells' score can be interpreted as follows:
- Low probability: score of 0-1
- Moderate probability: score of 2-6
- High probability: score of 7 or more
Comparison with Other Scores
The Wells' score has been compared to other clinical decision rules, such as the primary care rule 3 and a new score developed specifically for outpatients 4. These studies have shown that the Wells' score is a reliable and effective tool for assessing the pre-test probability of DVT.
Limitations of the Wells' Score
The Wells' score has been shown to have limitations, particularly in hospitalized patients and those with isolated distal DVT 2, 6. In these cases, alternative risk stratification models may be more effective in assessing the pre-test probability of DVT.
Clinical Application
The Wells' score is widely used in clinical practice to assess the pre-test probability of DVT in patients with suspected symptoms 2, 3, 4, 5. It can be used in combination with other diagnostic tests, such as D-dimer measurement and ultrasonography, to confirm or rule out DVT.