Should a diagnostic workup for pulmonary embolism (PE) always be performed in patients presenting with symptoms suggestive of PE, such as acute onset of chest pain and shortness of breath?

Diagnostic Workup for Suspected Pulmonary Embolism

A diagnostic workup for pulmonary embolism (PE) should always be performed in patients presenting with symptoms suggestive of PE, such as acute onset of chest pain and shortness of breath, using a structured approach based on clinical probability assessment followed by appropriate testing. 1

Clinical Probability Assessment

The first step in evaluating patients with suspected PE is to assess their clinical probability using validated tools:

• Wells score or revised Geneva score to categorize patients into low, intermediate, or high probability of PE 1, 2
• Clinical features suggesting PE include:
  • Dyspnea (present in 80% of PE cases)
  • Chest pain (present in 52% of cases)
  • Tachypnea (>20 breaths/min)
  • Tachycardia (>100 beats/min)
  • Syncope (present in 19% of cases)
  • Hemoptysis (present in 11% of cases) 1, 2

Diagnostic Algorithm

1. Hemodynamically Unstable Patients

• Proceed directly to CT pulmonary angiography (CTPA) if stable enough for transport 2
• If CTPA is not immediately available, bedside echocardiography to look for right ventricular dysfunction 1

2. Hemodynamically Stable Patients

Based on clinical probability assessment:

Low or Intermediate Probability:

• D-dimer testing 1
  • If negative → PE excluded (no further testing needed)
  • If positive → Proceed to CTPA
  • Consider age-adjusted D-dimer cutoffs for patients >50 years (age × 10 μg/L) 1, 2

High Probability:

• Proceed directly to CTPA without D-dimer testing 1
• D-dimer testing is not recommended in high probability patients as a normal result does not safely exclude PE 1

Imaging Modalities

First-Line Imaging:

• CT Pulmonary Angiography (CTPA) 1
  • Sensitivity: 83-100%
  • Specificity: 96-99%
  • Can identify alternative diagnoses

Alternative Imaging Options (when CTPA is contraindicated):

• V/Q Scan 1
  • A normal perfusion scan effectively excludes PE
  • Less useful when chest X-ray is abnormal
• Compression Ultrasound of lower extremities 1
  • Finding proximal DVT is sufficient to warrant anticoagulation without further testing
  • Sensitivity: 41% (limited)
  • Specificity: 96%

Important Caveats and Pitfalls

• Do not rely solely on clinical judgment without using structured assessment tools, as symptoms of PE can mimic other cardiopulmonary conditions 1, 2
• Do not skip D-dimer testing in low/intermediate probability patients, as it can safely exclude PE and avoid unnecessary radiation exposure 1
• Do not use D-dimer in high probability patients as false negatives can occur 1
• Do not delay anticoagulation in patients with high clinical probability while awaiting diagnostic confirmation 1
• Do not miss PE in pregnant patients where it remains a leading cause of maternal mortality 1
• Do not overlook alternative diagnoses that may present with similar symptoms 3

Special Populations

Pregnant Patients:

• Modified diagnostic approach with careful consideration of radiation exposure
• CTPA or V/Q scan may be used based on local expertise and patient factors 1

Cancer Patients:

• Higher risk of PE and higher risk of recurrence
• Same diagnostic algorithm applies, but lower threshold for suspicion 2

By following this structured approach to diagnosing PE, clinicians can ensure timely identification of this potentially fatal condition while avoiding unnecessary testing in low-risk patients.