How can I rapidly exclude pulmonary embolism in the emergency department using a simple scoring system?

Rapid Exclusion of Pulmonary Embolism in the Emergency Department

Use the Wells score or revised Geneva score to stratify clinical probability, then apply D-dimer testing (with age-adjusted cutoffs for patients >50 years) to safely exclude PE without imaging in low-to-intermediate probability patients. 1

Step 1: Apply PERC Rule for Very Low-Risk Patients

Before formal scoring, consider the Pulmonary Embolism Rule-Out Criteria (PERC) for patients with low clinical suspicion. All eight criteria must be met to safely exclude PE without any testing: 1

• Age <50 years
• Pulse <100 bpm
• Oxygen saturation >94%
• No hemoptysis
• No estrogen use
• No prior DVT/PE
• No unilateral leg swelling
• No surgery/trauma requiring hospitalization within 4 weeks

If all PERC criteria are met, PE is excluded with 99.1% negative predictive value and no further workup is needed. 2 However, PERC should only be applied in patients with genuinely low clinical suspicion—never in moderate or high probability patients. 3

Step 2: Calculate Clinical Probability Score

Revised Geneva Score (Fully Objective)

This is the most standardized approach as it requires no clinical judgment: 1

Assign points for:

• Previous PE or DVT: 3 points (original) or 1 point (simplified)
• Heart rate 75-94 bpm: 3 points (original) or 1 point (simplified)
• Heart rate ≥95 bpm: 5 points (original) or 2 points (simplified)
• Surgery or fracture within past month: 2 points (original) or 1 point (simplified)
• Hemoptysis: 2 points (original) or 1 point (simplified)
• Active cancer: 2 points (original) or 1 point (simplified)
• Unilateral lower-limb pain: 3 points (original) or 1 point (simplified)
• Pain on deep venous palpation and unilateral edema: 4 points (original) or 1 point (simplified)
• Age >65 years: 1 point (both versions) 1

Risk stratification:

• Low probability: 0-3 points (original) or 0-1 (simplified) = ~10% PE prevalence
• Intermediate probability: 4-10 points (original) or 2-4 (simplified) = ~30% PE prevalence
• High probability: ≥11 points (original) or ≥5 (simplified) = ~65% PE prevalence 1

Wells Score (Alternative)

The Wells score performs similarly to Geneva but includes subjective clinical judgment: 4

• Clinical signs of DVT: 3 points
• PE as likely or more likely than alternative diagnosis: 3 points
• Heart rate >100 bpm: 1.5 points
• Immobilization ≥3 days or surgery within 4 weeks: 1.5 points
• Previous PE/DVT: 1.5 points
• Hemoptysis: 1 point
• Malignancy: 1 point 1, 4

Dichotomized interpretation:

• PE unlikely: ≤4 points = ~12% PE prevalence
• PE likely: >4 points = ~30% PE prevalence 1, 4

Step 3: D-Dimer Testing Strategy

For Low or Intermediate Probability Patients

Obtain high-sensitivity D-dimer using age-adjusted cutoffs for patients >50 years old: 1

• Standard cutoff: <500 ng/mL excludes PE
• Age-adjusted cutoff: Age × 10 ng/mL for patients >50 years (e.g., 700 ng/mL for a 70-year-old)

The age-adjusted approach increases the proportion of patients in whom PE can be excluded from 6.4% to 30% without additional false-negative findings. 1, 3

If D-dimer is negative by these thresholds, PE is excluded with 99.5% negative predictive value and no imaging is needed. 4, 5

Critical Caveat About D-Dimer

Do NOT use D-dimer in high clinical probability patients—a normal result does not safely exclude PE even with highly sensitive assays. 1 D-dimer also has extremely limited utility in hospitalized patients, where fewer than 10% will have negative results due to comorbid conditions, recent surgery, infection, and inflammation. 3

Step 4: Imaging for Positive D-Dimer or High Probability

Proceed directly to CT pulmonary angiography (CTPA) without D-dimer testing in high probability patients or when D-dimer is elevated. 1, 3

CTPA has >95% sensitivity for segmental or larger emboli and 96% specificity. 3 A normal CTPA in low or intermediate probability patients definitively excludes PE without further testing. 1

Complete Algorithm Summary

1. Very low suspicion: Apply PERC rule → if all 8 criteria met, stop (no PE) 1
2. Low/intermediate probability (Wells ≤4 or Geneva 0-10): Check age-adjusted D-dimer 1
   • If negative → stop (no PE) 5
   • If positive → CTPA 1, 3
3. High probability (Wells >4 or Geneva ≥11): Skip D-dimer, proceed directly to CTPA 1

Common Pitfalls to Avoid

Never apply PERC in patients with moderate-to-high clinical probability—it was designed only for genuinely low-risk patients. 3 The PERC rule may miss up to 8% of confirmed PEs even in "PE unlikely" patients, so use cautiously. 2

Never rely on D-dimer alone in hospitalized patients or those with active cancer, recent surgery, or inflammatory conditions—proceed directly to imaging in these populations. 1, 3

Do not use clinical gestalt without structured scoring unless you are highly experienced—formal prediction rules standardize the approach and reduce missed diagnoses. 1