What is the most common finding in pulmonary embolism?

Most Common Finding in Pulmonary Embolism

Dyspnea (shortness of breath) is the most common finding in pulmonary embolism, present in approximately 80% of cases. 1, 2

Clinical Presentation of Pulmonary Embolism

• Dyspnea is the predominant symptom, which may be acute and severe in central PE or mild and transient in small peripheral PE 1, 2
• Pleuritic chest pain is the second most common symptom, present in about 52% of PE cases 1, 2
• Tachycardia is present in approximately 40% of patients, often being the only abnormality in milder cases 1
• Syncope occurs in about 19% of cases and is associated with a higher prevalence of hemodynamic instability and right ventricular dysfunction 1, 2
• Hemoptysis is less common but may occur due to pulmonary infarction 1
• In patients with pre-existing heart failure or pulmonary disease, worsening dyspnea may be the only symptom indicative of PE 1

Physiological Findings

• Hypoxemia is frequent, but up to 40% of patients have normal arterial oxygen saturation and 20% have a normal alveolar-arterial oxygen gradient 1
• Hypocapnia is often present due to hyperventilation 1
• Electrocardiographic changes indicative of right ventricular strain (such as inversion of T waves in leads V1-V4, QR pattern in V1, S1Q3T3 pattern, and right bundle branch block) are usually found in more severe cases 1

Radiographic Findings

• Chest X-ray is frequently abnormal but findings are usually non-specific 1
• Common chest X-ray findings include:
  • Pleural effusion (present in 46% of PE cases) 3
  • Atelectasis or infiltrate (49% of cases) 3
  • Decreased pulmonary vascularity (Westermark sign) (36% of cases) 3
  • Elevated diaphragm (36% of cases) 3
  • Pleural-based wedge-shaped opacity (Hampton's hump) (23% of cases) 3
• A normal chest X-ray in an acutely breathless hypoxic patient increases the likelihood of PE 1, 3

Clinical Implications

• The non-specific nature of symptoms makes PE diagnosis challenging, requiring a high index of clinical suspicion 1, 4
• Assessment of clinical probability using structured scores (Wells or Geneva) is a key step in diagnostic algorithms 1
• Transient symptoms can lead to delayed diagnosis or misdiagnosis, as patients may not seek medical attention if symptoms resolve quickly 2
• Even with transient symptoms, untreated PE carries a high risk of recurrence, which can be fatal 2

Diagnostic Approach

• A three-step approach is recommended for patients with stable hemodynamics:
  1. Assessment of clinical probability of PE using structured scores or clinical judgment 1, 4
  2. D-dimer testing if indicated (in low or intermediate probability) 1, 4
  3. Chest imaging (CTPA or V/Q scan) if indicated 1, 4
• In patients with high clinical probability (>40%), chest imaging should be performed directly without D-dimer testing 4

Common Pitfalls

• Relying solely on the presence of hypoxemia for diagnosis, as up to 40% of patients may have normal oxygen saturation 1
• Dismissing PE as a diagnosis when chest X-ray is abnormal, as findings are usually non-specific 1, 3
• Failing to maintain a high clinical suspicion for PE when symptoms are transient or have resolved at the time of evaluation 2
• Overlooking PE in patients with pre-existing cardiopulmonary disease, where worsening dyspnea may be the only new symptom 1