What is the management approach for patients with suspected pulmonary embolism (PE) using PE scores?

Management of Suspected Pulmonary Embolism Using PE Scores

Use validated clinical decision tools (Wells score or revised Geneva score) to stratify pretest probability, then apply age-adjusted D-dimer testing (age × 10 ng/mL for patients >50 years) or PERC criteria (for patients <50 years) to safely exclude PE without imaging in appropriate low-risk patients. 1, 2

Initial Risk Stratification

Begin by calculating pretest probability using a validated scoring system:

• Wells Score or Revised Geneva Score should be applied to all patients with suspected PE 1, 3
• Risk factors to assess include: recent immobility >1 week, major surgery, lower limb trauma/surgery, pregnancy/postpartum, previous VTE, active malignancy, and clinical signs of DVT 1
• Classify patients into low, intermediate, or high probability categories based on the scoring system 1, 3

Diagnostic Algorithm by Risk Category

Low Pretest Probability Patients

For patients <50 years old:

• Apply PERC criteria (all 8 must be negative): age <50, heart rate <100 bpm, oxygen saturation ≥95%, no unilateral leg swelling, no hemoptysis, no recent trauma/surgery, no prior VTE, no hormone use 2, 3
• If PERC-negative: PE is excluded, no further testing needed 2, 4
• If PERC-positive: proceed to D-dimer testing 2, 4

For patients ≥50 years old:

• Use age-adjusted D-dimer cutoff (age × 10 ng/mL) instead of standard 500 ng/mL cutoff 2
• This approach increases specificity from 10% to 35% in patients >80 years while maintaining high sensitivity 2
• If D-dimer is below age-adjusted threshold: PE is excluded 2, 4
• If D-dimer is elevated: proceed to CT pulmonary angiography 4

Intermediate Pretest Probability Patients

• Obtain D-dimer testing (age-adjusted if >50 years) 1, 2
• If D-dimer negative: PE is excluded 1
• If D-dimer positive: proceed to multidetector CT pulmonary angiography 1, 4
• If CT is negative but clinical concern persists, consider additional testing (lower extremity ultrasound, V/Q scan) 1

High Pretest Probability Patients

• Proceed directly to CT pulmonary angiography without D-dimer testing 1, 3
• Start anticoagulation immediately while diagnostic workup is ongoing unless contraindications exist 1
• If CT is negative, additional diagnostic testing is mandatory (lower extremity ultrasound, V/Q scan, or pulmonary angiography) before excluding PE 1

Imaging Modalities

CT Pulmonary Angiography (CTPA):

• Preferred first-line imaging modality with sensitivity >95% for segmental or larger PE 1
• A negative multidetector CTPA alone excludes PE in low and intermediate probability patients 1
• Sensitivity is approximately 75% for subsegmental PE, which may be clinically insignificant 1

Ventilation-Perfusion (V/Q) Scanning:

• Reserved for patients with contraindications to CTPA (renal insufficiency, contrast allergy, pregnancy) 1, 3
• Normal perfusion scan reliably excludes PE in low-to-moderate pretest probability patients 1
• Low probability V/Q scan combined with low clinical probability has <1% risk of PE 1

Lower Extremity Venous Ultrasound:

• Consider as first-line test in patients with clinical signs of DVT, previous PE, or chronic cardiopulmonary disease 1
• Positive ultrasound provides de facto evidence of VTE and justifies anticoagulation without need for pulmonary imaging 1

Critical Pitfalls to Avoid

Do not apply PERC to patients ≥50 years old - age <50 is a required criterion, making PERC invalid in older patients 2

Do not use standard 500 ng/mL D-dimer cutoff in elderly patients - specificity drops to 10% in patients >80 years, leading to excessive unnecessary imaging 2

Do not withhold anticoagulation in high-risk patients while awaiting imaging - start heparin immediately based on clinical suspicion 1

Do not accept single subsegmental PE on CTPA without radiologist confirmation - these findings have high false-positive rates and uncertain clinical significance 1

Do not rely on clinical gestalt alone with nondiagnostic V/Q scans - patients require additional imaging rather than management based solely on clinical features 1

Hemodynamically Unstable Patients

• Perform bedside transthoracic echocardiography immediately to differentiate high-risk PE from other causes of shock 1
• Initiate anticoagulation and select reperfusion strategy (systemic thrombolysis, surgical embolectomy, or catheter-directed treatment) based on available resources 1
• Thrombolytic therapy is indicated when systemic hypotension is present 1