Wells' Criteria for DVT

The Wells' Criteria for DVT can assist providers in identifying patients who are overall unlikely (low risk) to have a DVT. Further testing with d-dimer can safely rule our DVT without the need for an ultrasound. This tool is intended for the outpatient and emergency department setting, and only for patients who are considered at risk for DVT. The criteria is considered less useful in the hospital setting (Silveira, 2015). Depending on the research study, there are a few versions of the criteria with minor differences. The criteria set in this tool is the most widely validated (Wells, 2003).

Depending on the research study, there are a few versions of the criteria with minor differences. The criteria set in this tool is the most widely validated (Wells, 2003).

• High suspicion for DVT should warrant imaging regardless of Wells score.
• If pulmonary embolism (PE) is on the differential, consider additional decision aids, such as the Wells PE or PERC rule.

The formula consists of the sum of the selected points. Clinical gestalt is an important part of the score ("Alternative diagnosis to DVT as likely or more likely"). A "Yes" is given "-2" points.

Results

"Unlikely" (score ≤ 0): Low risk for DVT (5% prevalence).

Management: Proceed to d-dimer testing

• If negative (high or moderate sensitivity d-dimer), no further imaging is required (probability of DVT is <1%).
• If positive, proceed to US testing.
  • A negative US is sufficient for DVT rule out.
  • A positive US is concerning for DVT. Strongly consider anticoagulation treatment.

Moderate risk for DVT (Score 1-2). A score of 1-2 has a pretest DVT probability of 17%.

Management: Proceed to high-sensitivity d-dimer* testing

• If negative (high sensitivity d-dimer), no further imaging is required (probability of DVT is <1%).
• If positive, proceed to ultrasound testing.
  • A negative ultrasound is sufficient for DVT rule out.
  • A positive ultrasound is concerning for DVT. Strongly consider anticoagulation treatment.

*Moderate sensitivity d-dimer is not sufficient in this risk group to rule out without ultrasound.

"Likely" (score ≥ 3): High risk for DVT. A score of ≥ 3 has a pretest DVT probability of 17-53%.

Management: 

• All high-risk patients for DVT ("Likely") should receive ultrasound (US).
• Obtain D-dimer to further risk-stratify
  • If negative (d-dimer), 
    • A negative US is sufficient for ruling out DVT, consider discharge.
    • A positive US is concerning for DVT, consider anticoagulation treatment.
  • If positive (d-dimer),
    • A negative US is concerning for DVT. Consider repeat US within 1 week for re-evaluation.
    • A positive US is concerning for DVT. Strongly consider anticoagulation treatment.

Intended only for patients who are considered at risk for DVT.

• Less useful in hospitalized patients (Silveira, 2015).
• Clinical gestalt is an important part of the score ("Alternative diagnosis to DVT as likely or more likely"). A "Yes" is given "-2" points.