Wells Pretest Probability Score
Strategy for assessing PE and DVT
Even with the high sensitivity and negative predictive value of D-dimer testing, the D-dimer assay cannot be used alone to exclude venous thromboembolism (VTE); it must be used in combination with a pretest probability scoring system. The Wells scoring system is commonly used to assess a patient’s risk of having either a PE or DVT based on a number of clinical features.
Wells Pretest Probability Model to Assess PE
| Criteria | Points |
|---|---|
| Clinical signs and symptoms of DVT (objectively measured calf swelling or pain with palpation of deep vein region) | 3.0 |
| An alternative diagnosis is less likely than PE | 3.0 |
| Heart rate >100 beats per minute | 1.5 |
| Immobilization or surgery in the previous 4 weeks | 1.5 |
| Previous DVT or PE | 1.5 |
| Hemoptysis | 1.0 |
| Malignancy (on treatment, treated in the past 6 months, or palliative care) | 1.0 |
Interpretation of Point Total
| Score | Mean Probability | Risk |
|---|---|---|
| <2 points | 3.6 | Low |
| 2 to 6 points | 20.5 | Moderate |
| >6 points | 66.7 | High |
Wells Pretest Probability Model to Assess DVT
| Criteria | Points |
|---|---|
| Active cancer (patient either receiving treatment for cancer within the previous 6 months or currently receiving palliative treatment) | 1.0 |
| Paralysis, paresis, or recent case immobilization of the lower extremities | 1.0 |
| Recently bedridden for ≥3 days, or major surgery within the previous 12 weeks requiring general or regional anesthesia | 1.0 |
| Localized tenderness along the distribution of the deep venous system | 1.0 |
| Entire leg swelling | 1.0 |
| Calf swelling at least 3 cm larger than that on the asymptomatic side (measured 10 cm below tibial tuberosity) | 1.0 |
| Pitting edema confined to the symptomatic leg | 1.0 |
| Collateral superficial veins (non-varicose) | 1.0 |
| Previously documented deep vein thrombosis | 1.0 |
| Alternative diagnosis at least as likely as deep vein thrombosis | -2.0 |
Interpretation of Point Total
| Low probability | Moderate probability | High probability |
|---|---|---|
| -2 - 0 | 1-2 | 3-8 |