This interactive clinical decision tool calculates the pretest probability of pulmonary embolism (PE) using the validated Wells' Criteria. Results update automatically as you select criteria.
Select all criteria that apply to the patient. Results update instantly:
Select criteria to see detailed results and management recommendations.
Based on the Wells' Criteria score, the following diagnostic pathways are recommended:
PE Unlikely (0-4 points, 12.1% incidence): Consider high sensitivity d-dimer testing. If negative, stop workup. If positive, consider CTA.
PE Likely (>4 points, 37.1% incidence): Consider CTA testing. D-dimer testing is not recommended.
Follow these steps to effectively use the Wells' Criteria Calculator:
Evaluate the patient with suspected pulmonary embolism based on clinical presentation and history.
Click on all criteria that apply to the patient using the side-by-side selection buttons.
Results update automatically as you make selections. Examine risk classification, visualization, and management recommendations.
Generate a PDF report with results for medical records or consultation purposes.
Wells' Criteria is a clinical prediction rule that estimates the pretest probability of pulmonary embolism (PE) in patients with suspected PE based on clinical findings. It was developed to help clinicians determine which patients should undergo further diagnostic testing for PE.
In the traditional three-tier model, a score >6 indicates high probability of PE (approximately 37.5% incidence). In the two-tier model, a score >4 indicates 'PE Likely' (approximately 37.1% incidence).
No, this calculator is a clinical decision aid and should not replace clinical judgment. Physicians must first have suspicion of PE before applying the Wells criteria. The tool is designed to supplement, not replace, clinical evaluation and judgment.
The three-tier model classifies patients as low (<2 points), moderate (2-6 points), or high (>6 points) risk. The two-tier model classifies patients as "PE Unlikely" (0-4 points) or "PE Likely" (>4 points). Guidelines tend to favor the two-tier model for its simplicity and conservative risk stratification.
Age-adjusted d-dimer cutoffs have been validated for use in patients over 50 years in low risk patients. The formula is: Age (years) × 10 µg/L = cutoff. This adjustment increases the specificity of d-dimer testing in older patients while maintaining sensitivity.
This calculator is based on the following evidence-based sources:
For further information, consult these trusted medical resources: