Wells PE
Wells PE criteria: assess pulmonary embolism risk using 7 clinical signs. Free online clinical risk stratification tool with 2-tier and 3-tier classification.
About This Calculator
The Wells Criteria for Pulmonary Embolism (PE) Calculator helps clinicians assess the pre-test probability of pulmonary embolism using seven validated clinical parameters. Developed by Dr. Phil Wells and colleagues in 2001, this clinical prediction rule enables bedside risk stratification without requiring advanced diagnostic testing, making it an essential tool in emergency departments and hospital settings worldwide.
The Wells criteria assign weighted scores to seven clinical findings: clinical signs of deep vein thrombosis (3 points), PE as the most likely diagnosis (3 points), heart rate greater than 100 beats per minute (1.5 points), immobilization for three or more days or surgery within the past four weeks (1.5 points), prior objectively diagnosed DVT or PE (1.5 points), hemoptysis or coughing up blood (1 point), and active cancer with treatment within the past six months or palliative care (1 point). The total score ranges from 0 to 12.5 points.
The calculator provides both the traditional 3-level classification (low risk 0-1, moderate risk 2-6, high risk ≥7) and the clinically preferred 2-level classification (PE unlikely ≤4, PE likely ≥5) recommended by the ESC guidelines. The 2-tier approach is particularly useful for determining the diagnostic pathway: patients with PE unlikely classification should undergo D-dimer testing first, while those with PE likely classification should proceed directly to CT pulmonary angiography (CTPA) or ventilation-perfusion (V/Q) scanning for definitive diagnosis.
This Wells PE calculator applies the original scoring system as published in the Annals of Internal Medicine (2001) and validated in the Christopher Study (2006). While developed for use in North America and European populations, the Wells criteria have been extensively validated across diverse clinical settings globally and remain one of the most widely used clinical prediction rules for pulmonary embolism assessment alongside the revised Geneva score.
Frequently Asked Questions
What is the Wells score for pulmonary embolism?
The Wells score is a validated clinical prediction rule used to estimate the pre-test probability of pulmonary embolism (PE) before diagnostic imaging. It assigns weighted points to seven clinical criteria: clinical signs of DVT (3 points), PE as the most likely diagnosis (3 points), heart rate above 100 bpm (1.5 points), immobilization or surgery within four weeks (1.5 points), prior objectively diagnosed DVT or PE (1.5 points), hemoptysis (1 point), and active cancer within six months (1 point). Scores range from 0 to 12.5.
How is the Wells PE score interpreted with the 2-tier classification?
The 2-tier classification (from the Christopher Study) divides patients into two groups: a score of 4 or less indicates 'PE unlikely' with about 12% of patients expected to have confirmed PE, while a score of 5 or more indicates 'PE likely' with about 50% of patients expected to have confirmed PE. Patients with PE likely classification should proceed directly to CT pulmonary angiography (CTPA) or V/Q scan.
What are the three risk categories in the original Wells criteria?
The original 3-level Wells classification assigns patients to low risk (0-1 points, ~10% PE prevalence), moderate risk (2-6 points, ~30% PE prevalence), or high risk (7 or more points, ~65% PE prevalence). This traditional classification was proposed by Dr. Phil Wells in 2001 based on a study of 930 emergency department patients.
When should D-dimer testing be used instead of CTPA?
According to ESC guidelines, patients with a Wells score of 4 or less (PE unlikely) should first undergo D-dimer testing. D-dimer has a very high negative predictive value, meaning a negative result effectively excludes PE without the need for radiation exposure from CTPA. If D-dimer is positive, imaging is then warranted. Patients with a Wells score of 5 or more should proceed directly to CTPA or V/Q scan.
What clinical findings constitute signs of DVT in the Wells criteria?
Clinical signs of deep vein thrombosis include objective leg swelling (measurable difference in calf circumference), pain on deep vein palpation along the deep venous system, unilateral pitting edema, and collateral superficial veins. These signs are weighted at 3 points in the Wells criteria because PE and DVT represent the same disease process (venous thromboembolism) at different anatomical locations.
How is active cancer defined in the Wells criteria for PE?
In the Wells criteria, active cancer is defined as cancer that is currently receiving treatment, cancer for which treatment was terminated within the last 6 months, or cancer managed with palliative care. This criterion is worth 1 point. Cancer patients have a significantly increased risk of venous thromboembolism due to prothrombotic factors including tumor-derived procoagulants and chemotherapy-induced endothelial damage.
What is the difference between Wells criteria and the revised Geneva score?
Both Wells and revised Geneva scores are validated clinical prediction rules for PE pre-test probability. The Wells score includes the subjective criterion 'PE is the most likely diagnosis' (3 points), which relies on clinical gestalt and has been criticized for subjectivity. The revised Geneva score uses only objective parameters such as age, heart rate, clinical signs of DVT, surgery, prior VTE, cancer, hemoptysis, and unilateral leg pain, eliminating the subjective judgment component.
Can the Wells score definitively diagnose or exclude pulmonary embolism?
No, the Wells score is a clinical pre-test probability assessment tool, not a diagnostic test. It stratifies patients into risk categories to guide further testing. A low Wells score alone cannot definitively exclude PE — D-dimer testing is required. Similarly, a high Wells score does not confirm PE — imaging such as CTPA or V/Q scan is necessary for definitive diagnosis. The Wells score is always used in conjunction with D-dimer and imaging as part of the diagnostic pathway.