深部静脈血栓症（DVT）のウェルズスコアの総合ガイド

Comprehensive Guide to Wells Score for Deep Vein Thrombosis (DVT)

Deep Vein Thrombosis (DVT) is a life-threatening condition where blood clots form in deep veins, typically in the legs. It requires prompt diagnosis and treatment. Physicians rely on several tools to assess the likelihood of DVT, one of which is the Wells Score. This guide explores the Wells Score, detailing its inputs, outputs, and how it aids in diagnosing DVT.

What is the Wells Score?

The Wells Score is a clinical prediction rule used to estimate the probability of DVT. The score incorporates various clinical features and assigns points based on the presence of these factors, helping healthcare providers determine the likelihood of DVT.

Key Inputs for Wells Score Calculation

• Active Cancer: 1 point if the patient has active cancer (ongoing treatment, within 6 months, or palliative).
• Paralysis, Plegia, or Recent Plaster Immobility: 1 point for limb paralysis or recent plaster immobilization.
• Bedridden: 1 point if the patient has been recently bedridden for more than 3 days or had major surgery within the past 12 weeks.
• Tenderness Along Deep Vein System: 1 point for localized tenderness.
• Leg Swelling: 1 point if the entire leg is swollen.
• Calf Swelling: 1 point if calf swelling is greater than 3 cm compared to the asymptomatic side.
• Pitting Edema: 1 point for pitting edema in the symptomatic leg.
• Collateral Superficial Veins: 1 point if there are non-varicose collateral superficial veins.
• Previous DVT: 1 point if the patient has had a previous DVT.
• Alternative Diagnosis: Subtract 2 points if an alternative diagnosis is at least as likely as DVT.

How to Calculate the Wells Score

To calculate the Wells Score, sum the points from the listed factors. For example, if a patient has recent surgery (1 point), leg swelling (1 point), tenderness (1 point), and previous DVT (1 point), while an alternative diagnosis is as likely (-2 points), the Wells Score will be 2.

Interpreting the Wells Score

The final score falls into three probability categories: low, moderate, or high:

• 0 points: Low probability (<1% chance of DVT)
• 1-2 points: Moderate probability (17% chance of DVT)
• 3 points or more: High probability (75% chance of DVT)

Real-Life Example

Consider Jane, a 65-year-old woman who recently had hip surgery and has been bedridden. Jane experiences leg tenderness, swelling, and has a history of DVT. Using the Wells Score:

• Bedridden: 1 point
• Tenderness: 1 point
• Swelling: 1 point
• Previous DVT: 1 point
• Alternative Diagnosis: -2 points

Jane’s Wells Score is 2, indicating a moderate probability of DVT. Her physician may then decide to run further diagnostic tests.

Conclusion

The Wells Score is an invaluable tool in the clinical assessment of DVT likelihood. By evaluating specific risk factors and assigning a score, healthcare providers can make informed decisions about further diagnostics and treatment pathways. Understanding and correctly applying the Wells Score can significantly impact patient outcomes in clinical practice.