Pulmonary Embolism (PE) Risk Calculator (Wells Criteria)
Clinical decision support tool for assessing pre-test probability of pulmonary embolism using Wells Criteria. Stratifies patients into low, moderate, or high risk groups.
About
Pulmonary Embolism (PE) presents a diagnostic challenge in emergency medicine due to its variable clinical presentation. The Wells Criteria serves as a validated risk stratification tool to determine the pre-test probability of PE. By categorizing patients into risk groups, clinicians can standardize the decision to pursue D-dimer testing or proceed directly to CT Pulmonary Angiography (CTPA). This tool automates the scoring process, reducing cognitive load during critical assessment phases.
Misdiagnosis of PE carries severe consequences, including mortality from untreated embolism or complications from unnecessary anticoagulation. Conversely, overuse of imaging exposes patients to radiation and contrast nephropathy. Accurate risk stratification balances these concerns. This calculator utilizes the traditional point system, where specific clinical signs carry weighted integer values.
Formulas
The Wells Score is calculated by summing the weights of present clinical features:
Where w represents the weight of each positive criterion:
- Clinical signs of DVT: +3.0
- Alternative diagnosis less likely than PE: +3.0
- Heart Rate > 100: +1.5
- Immobilization or Surgery: +1.5
- Previous PE/DVT: +1.5
- Hemoptysis: +1.0
- Malignancy: +1.0
Reference Data
| Risk Category | Score Range | Clinical Probability (Incidence) | Recommended Action |
|---|---|---|---|
| Low Risk | 0 to 1 | 1.3% to 12% | Consider D-dimer (High Sensitivity) |
| Moderate Risk | 2 to 6 | 16% to 28% | D-dimer or CTA depending on sensitivity |
| High Risk | > 6 | 37.5% to 60% | CT Pulmonary Angiography (CTA) |
| PE Unlikely (Simplified) | ≤ 4 | 12% | High Sensitivity D-dimer |
| PE Likely (Simplified) | > 4 | 37% | Diagnostic Imaging |