Pulmonary Contusion
Pulmonary contusion is a common finding in chest trauma. This results from direct lung damage due to blunt force trauma, leading to hemorrhage and edema. Recognizing pulmonary contusions on imaging is important for early diagnosis, guiding management, and identifying potential complications.
Chest X-ray Findings in Pulmonary Contusion
Early X-ray Signs of Pulmonary Contusion
Chest X-ray (CXR) is often the first imaging modality used in trauma settings. However, pulmonary contusions may be subtle or even absent in the initial hours following injury. The findings of pulmonary contusion on X-ray includes:
Patchy, ill-defined opacities in lung parenchyma
Distribution typically conforming to the site of impact rather than anatomical lung segments
No air bronchograms, distinguishing it from consolidation in pneumonia
Rapid resolution within 24-48 hours (unlike pneumonia, which progresses over days)
Limitations of Chest X-ray in Detecting Contusions
While CXR is widely available, its sensitivity is limited, especially in supine trauma patients. Overlying rib fractures, patient positioning, and lung atelectasis can obscure contusions, leading to underdiagnosis.
CT Scan of the Chest: The Gold Standard for Pulmonary Contusion Diagnosis
How Pulmonary Contusions Appear on CT
Computed Tomography (CT) is the preferred imaging modality for detecting pulmonary contusions due to its superior sensitivity. Key CT findings include:
Ground-glass opacities (GGO) or consolidations localized to the area of impact
No clear borders, differentiating it from lung laceration, which has defined margins
Airspace filling without volume loss, unlike atelectasis, which causes lung collapse
Absence of interstitial thickening, helping to rule out pulmonary edema
Distribution Patterns on CT
Pulmonary contusions follow specific patterns based on the mechanism of injury:
Direct impact injuries: Contusions appear adjacent to fractured ribs or chest wall bruising.
Deceleration injuries: More common in high-speed trauma, contusions develop in deeper lung regions due to rapid lung movement against fixed structures (e.g., the spine).
Blast injuries: Can result in diffuse bilateral contusions, often accompanied by barotrauma-related changes like pneumothorax or pneumomediastinum.
Ultrasound in Trauma: Can It Detect Pulmonary Contusion?
Lung Ultrasound (LUS) Findings in Pulmonary Contusion
While ultrasound is not the first-line imaging tool for pulmonary contusions, it has gained popularity in trauma settings, particularly in point-of-care ultrasound (POCUS). Lung ultrasound may reveal:
B-lines: Indicating interstitial edema within the contused lung
Subpleural consolidations: Small areas of lung opacification near the pleura
Reduced lung sliding: If associated with adjacent rib fractures or pleural injury
Ultrasound is useful for detecting associated complications, such as pneumothorax or hemothorax, which frequently accompany pulmonary contusions.
Differentiating Pulmonary Contusion from Other Chest Pathologies
Pulmonary Contusion vs. Pulmonary Laceration
Pulmonary contusion: Ill-defined, patchy consolidation
Pulmonary laceration: Well-defined round or oval cavitary lesion with air-fluid levels
Pulmonary Contusion vs. Aspiration Pneumonitis
Pulmonary contusion: Occurs immediately post-trauma, localized to the site of impact
Aspiration pneumonitis: Develops over hours, often in dependent lung segments
Pulmonary Contusion vs. Pulmonary Edema
Pulmonary contusion: Unilateral, localized opacities with no interstitial involvement
Pulmonary edema: Bilateral, diffuse opacities with interstitial thickening and cardiomegaly (if cardiogenic)
Complications of Pulmonary Contusion on Imaging
Delayed Worsening and Acute Respiratory Distress Syndrome (ARDS)
Though contusions may initially appear mild, worsening respiratory function over 24-48 hours can indicate evolving complications. Imaging features suggestive of ARDS include:
Progressive bilateral lung opacities on CXR or CT
Ground-glass opacities merging into diffuse consolidation
Air bronchograms due to alveolar flooding
Superimposed Infection and Pneumonia
Pulmonary contusions increase the risk of pneumonia, especially in ventilated or immobilized patients. Signs of infectious complications on imaging include:
New focal consolidations with air bronchograms
Development of cavitary lesions (suggesting abscess formation)
Pleural effusions, often indicating parapneumonic effusion or empyema
Pneumothorax and Hemothorax
Contusions frequently coexist with pleural injuries, leading to pneumothorax (air in the pleural space) or hemothorax (blood accumulation). CT is superior to X-ray in detecting small pneumothoraces, which may require close monitoring or intervention.
Management and Follow-Up Imaging
Pulmonary contusions typically resolve within 5-7 days without intervention, but serial imaging is important in patients with worsening respiratory symptoms. Follow-up CT or X-ray can help assess resolution or detect complications such as:
Persistent consolidation suggesting pneumonia
Scarring changes in severe contusions
Progressive pleural effusions requiring drainage
Personal Insight from Radiology Practice
In my experience, pulmonary contusions are often underestimated on initial chest X-rays, particularly in supine trauma patients. A follow-up CT scan frequently reveals more extensive lung injury than initially suspected. This indicates the importance of correlating imaging with clinical symptoms, as even mild X-ray findings can precede significant respiratory decline.
Conclusion
Pulmonary contusions are an important radiologic finding in chest trauma. While chest X-rays are commonly used for initial assessment, CT scans provide more detail, allowing differentiation from other lung injuries and guiding management decisions.
Radiologists play an important role in identifying contusions early, assessing for complications, and aiding in clinical decision-making. Prompt recognition on imaging can significantly impact patient outcomes, ensuring appropriate monitoring and treatment when necessary.
References
1.https://my.clevelandclinic.org/health/diseases/pulmonary-contusion
2.https://jtd.amegroups.org/article/view/25393/html
3.https://www.ncbi.nlm.nih.gov/books/NBK558914/