What is the Wells Score for PE?

It is a clinical decision tool that estimates the probability of pulmonary embolism using seven clinical criteria. Scores can be interpreted using a three-tier model (low/moderate/high) or a two-tier model (PE unlikely ≤4, PE likely >4). It guides the choice between D-dimer testing and CT angiography.

What do the risk levels mean for workup?

Low risk ( 6): proceed directly to CTPA without waiting for D-dimer.

When is PE considered 'likely' by Wells?

In the two-tier Wells model, a score >4 is PE likely and generally warrants imaging if PE remains a concern. A score ≤4 is PE unlikely and is usually paired with D-dimer first.

CT Pulmonary Angiography is the gold standard imaging test for diagnosing pulmonary embolism. It uses IV contrast and CT scanning to directly visualize blood clots in the pulmonary arteries. It is fast, widely available, and has high sensitivity and specificity.

What is the difference between Wells DVT and Wells PE?

They are two separate scoring systems. The [Wells DVT score](/tools/wells-dvt) has 10 criteria and evaluates deep vein thrombosis probability. The Wells PE score has 7 criteria and evaluates pulmonary embolism probability. They share some risk factors but are used for different clinical questions.

What is the PE prevalence by Wells category?

Low probability ( 6): ~66.7% have PE. These prevalences inform how we interpret D-dimer and imaging.

What is the PERC rule?

[Pulmonary Embolism Rule-out Criteria (PERC)](/tools/perc-rule) can rule out PE without D-dimer if all 8 criteria are negative: age <50, HR <100, O2 sat ≥95%, no hemoptysis, no estrogen use, no prior DVT/PE, no unilateral leg swelling, no surgery/trauma requiring hospitalization in past 4 weeks.

When should I use PERC vs. Wells?

Use [PERC](/tools/perc-rule) first in patients with LOW clinical suspicion (gestalt: <15% probability). If all PERC criteria are negative, no further testing is needed. If any PERC is positive or suspicion is moderate/high, proceed to Wells scoring and D-dimer.

What is subsegmental PE?

Subsegmental PE is clot in the smallest pulmonary arteries. Clinical significance is debated. Many are incidental findings on CTPA done for other reasons. Treatment decisions should consider clinical context and patient bleeding risk.

Can Wells rule out massive PE?

Wells stratifies probability, not severity. A patient with massive PE (hemodynamic instability) should have immediate imaging regardless of score. Wells is for stable patients where PE is possible but not certain.

What if CTPA is contraindicated?

Alternatives: V/Q scan (best for normal chest X-ray, no COPD), lower extremity ultrasound (if DVT found, can treat VTE without lung imaging), or MRA (less validated). Discuss with radiology.

How do I score immobilization?

Immobilization means ≥3 days of bedrest, OR major surgery requiring general anesthesia in the past 4 weeks. Minor procedures and limited activity don't count.

Is Wells valid for outpatients?

Yes. Wells was validated in both inpatient and outpatient populations. It applies to ED patients who may be discharged and to clinic patients with suspected PE.

What is the YEARS algorithm?

YEARS is an alternative approach: assess 3 items (DVT signs, hemoptysis, PE most likely diagnosis) plus age-adjusted D-dimer. If 0 items and D-dimer <1000, or ≥1 item and D-dimer <500, PE is ruled out without imaging.

Can PE and DVT occur together?

Yes. PE results from emboli, usually from DVT. About 50% of patients with proximal DVT have asymptomatic PE. About 70% of PE patients have DVT on ultrasound. Finding DVT changes your management approach.

What anticoagulation do I start for PE?

Unless contraindicated, start anticoagulation immediately upon diagnosis. Options include DOACs (preferred for most), LMWH, or heparin infusion (for high-risk PE or renal failure). Duration is typically 3+ months depending on provoked vs. unprovoked.

Online Medical Tools — Wells Score (PE)

Printed on 8/14/2026

For informational purposes only. This is not medical advice.

Emergency

Wells Score (PE)

The Wells Score for PE is a clinical prediction tool that estimates the pre-test probability of pulmonary embolism. It uses clinical signs, symptoms, and risk factors to stratify patients into low, moderate, or high probability categories, guiding the clinician's decision on whether to order D-dimer testing or proceed directly to CT pulmonary angiography (CTPA).

Formula: Wells PE = DVT symptoms(3) + PE likely(3) + HR>100(1.5) + Immobilization(1.5) + Previous(1.5) + Hemoptysis(1) + Cancer(1)

Clinical Signs/Symptoms of DVT

PE is #1 Diagnosis, or Equally Likely

Heart Rate > 100 bpm

Immobilization or Surgery in Past 4 Weeks

Previous DVT/PE

Hemoptysis

Active Cancer (treatment within 6 months)

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How It Works

Assess clinical signs and symptoms

Evaluate for DVT signs (leg swelling, calf tenderness), check heart rate, review recent immobilization or surgery, and consider whether PE is the most likely diagnosis.

Score each criterion

Award points for each positive finding. Clinical signs of DVT and 'PE most likely' are worth 3 points each; other criteria range from 1-1.5 points.

Determine diagnostic pathway

Low probability: check D-dimer. Moderate: D-dimer with CTPA if positive. High probability (>6): proceed directly to CTPA imaging.

Who Uses the Wells Score (PE)

ED Dyspnea/Chest Pain Workup

Emergency physicians

Stratify patients presenting with shortness of breath, chest pain, or hypoxia to determine whether PE workup is indicated and how to proceed. Assess oxygenation deficits with [A-a Gradient](/tools/aa-gradient) if hypoxic.

Post-Operative PE Evaluation

Surgeons, hospitalists

Evaluate post-surgical patients with new dyspnea or tachycardia. Recent surgery adds 1.5 points, increasing pre-test probability. For ICU patients with suspected PE, also calculate [APACHE II](/tools/apache-ii) or [SOFA Score](/tools/sofa-score) for severity assessment.

Cancer Patient Assessment

Oncologists, palliative care

Assess cancer patients with pulmonary symptoms. Cancer increases VTE risk; active malignancy adds 1 point to Wells PE.

Clinical Pathway Integration

Quality teams, EHR analysts

Build Wells PE into electronic decision support to ensure consistent, evidence-based PE evaluation across providers.

Radiation Stewardship

Radiologists, ED directors

Use D-dimer to avoid unnecessary CTPAs in low-probability patients, reducing radiation exposure and contrast administration.

Teaching Tool

Medical education

Train residents and students in structured PE evaluation. Wells provides a framework for systematic pre-test probability assessment.

Pro Tips

'PE most likely' is subjective but critical

This 3-point criterion asks whether, considering all alternatives, PE is your leading diagnosis. It incorporates clinical gestalt. If you think pneumonia (assess with [CURB-65](/tools/curb-65)) or pleuritis is more likely, don't check this box.

Use PERC before Wells for very low-risk patients

If PE suspicion is low (not 'PE most likely'), apply PERC criteria first. All 8 negative = no further testing needed. PERC can save you from ordering even a D-dimer.

Clinical signs of DVT means both leg AND exam findings

Score 3 points only if the patient has both leg symptoms AND objective swelling/tenderness. Just leg pain without signs doesn't count. Examine the legs on every PE evaluation.

High-probability patients need imaging, not D-dimer

Wells >6 has ~67% PE prevalence. D-dimer can't rule out PE at this prevalence — the false-negative rate is unacceptable. Go directly to CTPA.

Age-adjusted D-dimer applies here too

For patients >50 years, use age × 10 µg/L as the D-dimer threshold. This increases specificity in older patients while maintaining sensitivity.

Heart rate is measured at presentation

Use the heart rate from triage or initial assessment. If it was >100 then but is now 95 after anxiolysis, the point still counts. Document the initial HR.

Consider V/Q scan if CTPA contraindicated

For patients with contrast allergy, severe renal disease (check [eGFR Calculator](/tools/egfr-calculator) or [Creatinine Clearance](/tools/creatinine-clearance)), or pregnancy, V/Q scanning is an alternative. Low-probability V/Q + low clinical probability rules out PE.

Hemoptysis in PE is usually small-volume

PE-associated hemoptysis is typically blood-streaked sputum from pulmonary infarction. Massive hemoptysis suggests other diagnoses. Any hemoptysis scores 1 point.

Pregnancy complicates the algorithm

D-dimer is elevated in pregnancy. Many experts recommend compression ultrasound first (looking for DVT); if positive, treat without CTPA. If negative, V/Q or CTPA depending on gestational age (calculate with [Pregnancy Due Date Calculator](/tools/pregnancy-due-date)).

Document the score and your reasoning

Write 'Wells PE = 4.5, proceeding with D-dimer' in your note. This documents your systematic approach and helps colleagues understand your decision-making.

Common Questions About Your Results

Evidence-Based Methodology

Wells PE Score was developed by Wells et al. (Thromb Haemost 2000) and has been extensively validated. PERC was developed by Kline et al. (J Thromb Haemost 2004) to identify patients who don't need D-dimer. Age-adjusted D-dimer thresholds are supported by ADJUST-PE (JAMA 2014) and subsequent meta-analyses.

Clinical Content Trust

Last reviewed:: April 21, 2026
Guideline version:: General evidence framework v2026.04
Source set version:: Primary-source set v1

How to Interpret Your Result

Your Wells PE score estimates the pre-test probability of pulmonary embolism. Using the three-tier model, a score below 2 indicates low probability (approximately 3.6% PE prevalence), 2–6 points indicates moderate probability (approximately 20.5%), and above 6 points indicates high probability (approximately 66.7%). Using the simplified two-tier model, a score of 4 or below is PE unlikely, and above 4 is PE likely.

As with the DVT score, this result guides the diagnostic workup rather than providing a definitive diagnosis. Low-probability patients can be evaluated with D-dimer first — a negative D-dimer in this group effectively rules out PE. Moderate-probability patients should have D-dimer testing, with CT pulmonary angiography (CTPA) if the D-dimer is positive. High-probability patients should proceed directly to CTPA without waiting for D-dimer results.

When to Use This Tool

Use this calculator when evaluating a patient with symptoms that could represent pulmonary embolism — including acute dyspnea, pleuritic chest pain, tachycardia, hemoptysis, or unexplained hypoxia. It is a cornerstone of the PE diagnostic algorithm recommended by major guidelines (ACEP, BTS, ESC) and helps clinicians decide whether D-dimer testing alone is sufficient or whether imaging is needed.

The score is most impactful in the emergency department, where PE is a common diagnostic consideration for chest pain and dyspnea. By identifying patients with low pre-test probability who can be safely cleared with a negative D-dimer, it reduces unnecessary CTPA imaging — avoiding radiation exposure, contrast dye risks, and incidental findings that may lead to further testing.

Limitations

The Wells PE score includes a highly subjective criterion: whether PE is the most likely diagnosis (worth 3 points). This element accounts for the clinician's gestalt and can swing the total score significantly, introducing inter-rater variability. Some studies have shown that experienced clinicians sometimes outperform the formal score using gestalt alone, while less experienced clinicians benefit more from structured scoring.

The score was validated in outpatient and emergency department populations and may not perform optimally in hospitalized or post-operative patients where the baseline prevalence of PE is different. It does not account for certain PE-specific risk factors such as recent long-haul air travel, thrombophilia, or nephrotic syndrome as independent criteria. In pregnant patients, the score has limited validation and clinical algorithms typically differ. Additionally, the PERC (Pulmonary Embolism Rule-out Criteria) rule may be more appropriate than Wells for very low-risk patients to avoid unnecessary D-dimer testing altogether.

Disclaimer: This tool is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your health.

Changelog

April 21, 2026 · trust-baseline
Clinical trust metadata enabled for this tool page with structured review/version fields.

Used in Clinical Pathways

Pulmonary Embolism (PE) Workup

PERC → Wells PE Score → Age-Adjusted D-Dimer

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