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BackTable / VI / Tool
Wells' Criteria for Pulmonary Embolism
The Wells' criteria PE calculator is a clinical decision-making tool designed to assess the probability of a pulmonary embolism (PE) in patients presenting with symptoms suggestive of this life-threatening condition. A pulmonary embolism occurs when a blood clot, usually originating from a deep vein thrombosis (DVT) in the legs or pelvis, travels to the lungs and obstructs blood flow. Rapid diagnosis and treatment are crucial to prevent severe complications or death.
This calculator uses the Wells' criteria, which is a set of clinical parameters developed by Dr. Phil Wells and his colleagues in 1998. It has been widely accepted and utilized by healthcare professionals to stratify patients into different risk categories based on the likelihood of having a PE.
To use the Wells' criteria PE calculator, clinicians input patient-specific data, such as signs and symptoms of DVT, heart rate, recent surgery or immobilization, and the presence of hemoptysis. The calculator then assigns points to each criterion, and the total score determines the patient's risk category: low, moderate, or high probability of PE.
Based on the risk category, the clinician may proceed with additional diagnostic testing, such as D-dimer testing or imaging studies like computed tomography pulmonary angiography (CTPA) or ventilation-perfusion (V/Q) scanning, to confirm or rule out the presence of a PE. The Wells' criteria PE calculator is a valuable tool that helps streamline the diagnostic process, allowing for quicker, more informed decision-making and potentially improving patient outcomes.
Wells' Criteria for Pulmonary Embolism
Clinical signs and symptoms of DVT
PE is #1 diagnosis OR equally likely
Heart rate > 100
Immobilization at least 3 days or surgery in the previous 4 weeks
Previous, objectively diagnosed PE or DVT
Hemoptysis
Malignancy with treatment within 6 months or palliative
Value
Alternative diagnosis to DVT as likely or more likely
Alternative diagnosis to DVT as likely or more likely
How to Use the Calculator and Interpret Results
To use the calculator, select all applicable clinical criteria. The tool automatically sums the total Wells score for PE and classifies the patient into a risk category. The Wells Criteria for PE:
• Clinical signs of DVT (3 points)
• PE is #1 diagnosis OR equally likely (3 points)
• Heart rate >100 bpm (1.5 points)
• Immobilization ≥3 days or surgery within the past 4 weeks (1.5 points)
• Previous, objectively diagnosed PE or DVT (1.5 points)
• Hemoptysis (1 point)
• Malignancy (treatment within 6 months or palliative care) (1 point)
Three-tier model scoring interpretation:
• Low Risk (0–1 points): ~1.3% probability of PE. Consider a D-dimer to rule out PE; no imaging if negative.
• Moderate Risk (2–6 points): ~16.2% probability of PE. D-dimer or imaging depending on clinical context.
• High Risk (≥7 points): ~37.5% probability of PE. Recommend immediate imaging (e.g., CT pulmonary angiography).
Two-tier model scoring interpretation:
• PE Unlikely (≤4 points): Tested with a d-dimer and a 3% incidence of PE.
• PE Likely (>4 points): Straight to CTPA and a 28% incidence of PE.
This Wells score PE calculator helps streamline decision-making and minimize unnecessary testing when paired with D-dimer results.
Clinical Considerations and Best Practices
The Wells criteria for PE is especially useful in ambulatory or emergency settings where rapid triage decisions are needed. When used alongside D-dimer testing, it can help rule out PE without imaging in low-risk patients—supporting safer and more cost-effective care.
However, it's important to use the Wells criteria PE tool as part of a broader clinical picture. The score depends on subjective elements like whether PE is considered the most likely diagnosis, which can vary between clinicians. In hospitalized or high-risk populations, consider that pretest probability may already be elevated.
For best results:
• Pair with age-adjusted D-dimer testing.
• Reassess if new symptoms emerge.
• Document reasoning when using subjective elements like "PE most likely."
Learn more on the BackTable VI Podcast
BackTable is a knowledge resource for physicians by physicians. Get practical advice on the Wells' Criteria for Pulmonary Embolism and how to build your practice by listening to the BackTable VI Podcast, reading exclusing BackTable Articles, and following the work of our Contributors.
References
[1] Wells, P. S., et al. "Excluding pulmonary embolism at the bedside without diagnostic imaging: management of patients with suspected pulmonary embolism presenting to the emergency department by using a simple clinical model and D-dimer." Annals of Internal Medicine, 2001.
[2] Anderson, D. R., et al. "Accuracy of clinical assessment of deep-vein thrombosis." The Lancet, 2003.
[3] Wells, P. S., et al. "Evaluation of D-dimer in the diagnosis of suspected deep-vein thrombosis." New England Journal of Medicine, 2003.
Disclaimer: The Materials available on BackTable.com are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
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