What chest X‑ray findings are suggestive of pulmonary thromboembolism?

Chest X-ray Findings in Pulmonary Thromboembolism

Chest radiography is rarely diagnostic for pulmonary embolism and is most commonly abnormal in non-specific ways, but its critical value lies in excluding alternative diagnoses such as pneumonia, pneumothorax, heart failure, or tumor. 1

Common Radiographic Findings in PE

The chest X-ray is abnormal in approximately 88% of patients with confirmed PE, though findings lack specificity: 2

• Atelectasis or parenchymal infiltrate is the most common finding, present in 49% of PE cases (but also in 45% of non-PE cases), making it a poor discriminator 3, 2
• Pleural effusion occurs in 46% of PE patients versus 33% in non-PE patients 3
• Elevated hemidiaphragm is seen in 36% of PE cases compared to 25% in non-PE cases 3
• Decreased pulmonary vascularity (Westermark sign) appears in 36% of PE cases, representing reduced blood flow to affected lung regions 3
• Amputation of hilar artery is present in 36% of PE cases but only 1% of non-PE cases, making it more specific when identified 3
• Pleural-based wedge-shaped opacity (Hampton's hump) occurs in 23% of PE cases and represents pulmonary infarction 3, 2

Diagnostic Value and Limitations

The chest radiograph should never be used to diagnose or exclude PE—additional imaging with CT pulmonary angiography or V/Q scanning is always required for confirmation. 1

Key clinical considerations:

• A normal chest X-ray in an acutely breathless, hypoxic patient actually increases the likelihood of PE and should heighten clinical suspicion 1
• Only 12% of patients with confirmed PE have a completely normal chest radiograph 2
• The primary utility of chest radiography is to identify alternative diagnoses (pneumonia, pneumothorax, heart failure, rib fracture, aortic dissection) that can mimic PE clinically 1, 4
• A good quality chest radiograph is essential for accurate interpretation of ventilation-perfusion scans 1

Algorithmic Approach to Suspected PE

When chest X-ray findings raise suspicion for PE:

1. Assess clinical probability using Wells score or revised Geneva score to stratify patients into low, intermediate, or high probability categories 3, 5

2. For low clinical probability patients: Apply PERC criteria (all 8 must be met) to identify those needing no further testing; if PERC fails, obtain age-adjusted D-dimer 5

3. For intermediate clinical probability patients: Obtain high-sensitivity D-dimer with age-adjusted cutoffs (age × 10 ng/mL for patients >50 years); if negative, PE is excluded 5

4. For high clinical probability patients: Proceed directly to CT pulmonary angiography without D-dimer testing, as negative D-dimer does not reliably exclude PE in this population 5

Critical Pitfalls to Avoid

• Do not rely on specific radiographic signs (Hampton's hump, Westermark sign, Fleischner sign) to diagnose PE—these are insensitive and non-specific 2
• Do not dismiss PE based on a normal chest X-ray—18% of confirmed PE cases have normal radiographs 6
• Do not use chest X-ray findings alone to guide anticoagulation decisions—definitive imaging with CTPA is mandatory 1, 3
• Do not delay CTPA in high-probability patients while waiting for chest X-ray results or D-dimer testing 5
• Recognize that cardiomegaly (38%) and pulmonary infiltrates (34%) are the most common findings but are entirely non-specific 6