What is the risk of pulmonary embolism (PE) in this patient?

Risk Assessment for Pulmonary Embolism

The risk of pulmonary embolism (PE) should be assessed using validated clinical prediction rules such as the revised Geneva score or Wells criteria, which can categorize patients into low, intermediate, or high probability of PE based on clinical presentation and risk factors. 1

Clinical Prediction Rules

Revised Geneva Score

The revised Geneva score is an objective, standardized clinical prediction rule that includes the following variables:

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

Risk stratification:

• Low risk: 0-3 points (PE prevalence ~10%)
• Intermediate risk: 4-10 points (PE prevalence ~30%)
• High risk: ≥11 points (PE prevalence ~65%) 1

Wells Criteria

An alternative validated prediction rule that includes a subjective component ("alternative diagnosis less likely than PE"), which may reduce inter-observer reproducibility 1.

Risk Stratification Approach

1. Assess hemodynamic stability first:

   • Presence of shock or hypotension indicates high-risk PE (mortality risk >15%)
   • Cardiac arrest, obstructive shock, or persistent hypotension are clinical manifestations of high-risk PE 1

2. For hemodynamically stable patients:

   • Apply clinical prediction rule (revised Geneva or Wells score)
   • Consider age, comorbidities, and clinical presentation
   • Evaluate for signs of right ventricular dysfunction (via imaging or biomarkers) 1

3. Risk categories based on ESC guidelines:

   • High-risk PE: Shock or hypotension present
   • Intermediate-risk PE: No shock/hypotension but has RV dysfunction signs and/or elevated cardiac biomarkers
   • Low-risk PE: No shock/hypotension, no RV dysfunction, normal cardiac biomarkers 1

Special Considerations

Kline Decision Rule

The Kline rule can identify patients at higher risk of PE who should not undergo D-dimer testing alone. "Unsafe" patients (higher PE risk ~42%) have either:

• Shock index (heart rate/systolic BP) >1.0 OR
• Age >50 years PLUS any of:
  • Unexplained hypoxemia (SaO₂ <95%, no prior lung disease)
  • Unilateral leg swelling
  • Recent major surgery
  • Hemoptysis 1

Cancer Patients

Cancer patients have a higher baseline risk for PE, and clinical prediction rules may be less accurate in this population. The Wells criteria and D-dimer testing have been shown to be less predictive in cancer patients, with most requiring imaging for diagnosis 1.

Critically Ill Patients

Standard prediction rules (Wells and revised Geneva) may not be reliable in critically ill patients, with studies showing poor predictive value in this population 2.

Common Pitfalls to Avoid

1. Relying solely on D-dimer in high-risk patients: D-dimer testing should be avoided in patients with high clinical probability (>40%) as a negative result does not reliably exclude PE 1

2. Overlooking hemodynamic assessment: Initial risk stratification should always include assessment for shock or hypotension, which immediately classifies a patient as high-risk PE 1

3. Misinterpreting clinical signs: Sinus tachycardia is present in only 40% of PE patients, and classic symptoms may be absent or subtle 1

4. Ignoring concomitant DVT: The presence of DVT increases the risk of death within the first 3 months after acute PE 1

5. Underestimating PE in special populations: Standard prediction rules may be less accurate in cancer patients, pregnant women, and critically ill patients 1, 3, 2

Remember that the clinical prediction rules help guide diagnostic workup but should not replace clinical judgment, especially in unstable patients where empiric treatment may be necessary while awaiting diagnostic confirmation.