What is the Wells Criteria?

The Wells Criteria is a validated clinical prediction rule that assigns points to specific signs, symptoms, and history elements to estimate the pre-test probability of pulmonary embolism before ordering confirmatory imaging.

What score means high probability?

A Wells score greater than 6 indicates high probability (approximately 40–67% chance of PE). Scores of 2–6 indicate moderate probability (~20%), and scores below 2 indicate low probability (~3%).

Can this tool replace physician judgment?

No. This tool is for educational and clinical reference only. All diagnostic and treatment decisions must be made by a licensed clinician who has directly evaluated the patient.

What is the difference between the 2-tier and 3-tier Wells models?

The 3-tier model stratifies patients into Low ( 6) risk categories. The 2-tier (simplified) model uses PE Likely (> 4) vs. PE Unlikely (≤ 4). This tool uses the 3-tier model.

When should I order CT pulmonary angiography?

CT-PA is typically recommended for patients with high Wells scores (> 6), for those with moderate scores plus a positive D-dimer, or when clinical suspicion remains high despite a negative D-dimer.

How do the PERC rule and Wells criteria work together?

They serve different roles. The Wells criteria estimate pre-test probability of PE. The PERC rule is applied only to low-risk patients to decide whether even a D-dimer can be safely skipped. Use Wells first; if low risk, then check PERC.

Wells Criteria for PE

Score Wells criteria risk factors to determine low, moderate, or high pre-test probability of pulmonary embolism.

Clinical Criteria

Check all that apply to the patient.

Clinical signs and symptoms of DVT +3

Leg swelling, pain with palpation of deep veins

PE is the #1 diagnosis, or equally likely +3

Alternative diagnoses less likely than PE

Heart rate > 100 bpm +1.5

Tachycardia at time of evaluation

Immobilization ≥ 3 days OR surgery in past 4 weeks +1.5

Bed rest or recent operative procedure

Previous DVT or PE +1.5

Objectively diagnosed prior event

Hemoptysis +1

Coughing up blood

Malignancy (treatment within 6 months or palliative) +1

Active cancer or on treatment

Wells Score

0 Total Points

Low Probability

~3% chance of PE

Recommended Next Step

D-dimer testing. If negative, PE can be excluded. If positive, consider further imaging.

Score Reference

Low < 2 pts — ~3%

Moderate 2 – 6 pts — ~20%

High > 6 pts — ~40–67%

For clinical reference only. All diagnostic decisions must be made by a licensed clinician.

Summary

The Wells Criteria for Pulmonary Embolism (PE) is a validated clinical scoring system used to estimate the pre-test probability that a patient has a PE. By checking off clinical findings and risk factors, clinicians generate a score that guides the next diagnostic step — from D-dimer testing in low-risk patients to immediate CT pulmonary angiography in high-risk cases. This tool implements the original Wells scoring rubric for educational and clinical reference purposes.

How it works

Review each of the seven clinical criteria listed in the scoring panel.
Check every criterion that applies to the patient being evaluated.
The tool sums the points and displays the total Wells score.
Based on the score, a risk category (Low, Moderate, or High) is shown.
Use the recommended next step as a guide for further diagnostic workup.

Use cases

Estimate pre-test probability of PE in the emergency department.
Decide whether a D-dimer test is sufficient or CT-PA is needed.
Support clinical documentation with an objective risk score.
Teach medical students and residents the Wells scoring logic.
Cross-check bedside clinical impression against a validated rubric.
Apply to patients presenting with dyspnea, chest pain, or unexplained tachycardia.

Frequently Asked Questions

Last updated: 2026-05-23 · Reviewed by Nham Vu