Can You Request a Plain Chest CT Scan to Rule Out Chest Injury Due to Trauma?
You should request a contrast-enhanced CT chest, not a plain (non-contrast) CT, as the preferred imaging for suspected chest trauma because contrast-enhanced CT has superior sensitivity for detecting vascular injuries and provides comprehensive evaluation of all thoracic structures that impact mortality and morbidity. 1
Why Contrast-Enhanced CT is Superior to Plain CT
Contrast-enhanced CT of the chest is the gold standard for evaluating suspected chest trauma because it detects both parenchymal injuries (rib fractures, pneumothorax, hemothorax, pulmonary contusion) AND vascular injuries that can be life-threatening. 1
Plain (non-contrast) CT has significant limitations:
- Lower sensitivity for detecting vascular injuries, which are critical for mortality outcomes 1
- Cannot adequately evaluate for aortic injury, cardiac injury, or active bleeding 1
- May miss hemothorax versus hemopericardium differentiation that requires immediate intervention 1
When Plain CT May Be Acceptable
Plain CT chest is only appropriate in specific limited scenarios:
- Patients with contraindications to IV contrast (severe contrast allergy, acute kidney injury) 1
- Patients with prior chest surgery or retained metal fragments where contrast may cause artifacts 1
- Detection of sternal fractures using sagittal and 3-D reconstructions 1, 2
- Identifying hemothorax or hemopericardium by measuring attenuation values, though this still requires follow-up contrast study to identify the bleeding source 1
Clinical Algorithm for Chest Trauma Imaging
Step 1: Initial Screening
- Portable AP chest radiograph screens for immediate life-threatening findings (tension pneumothorax, significant mediastinal injury) and confirms line placement 1
- However, chest radiographs miss 40% of injuries detected on CT, including half of all pneumothoraces, pulmonary contusions, and rib fractures 1
Step 2: Definitive Imaging
- Hemodynamically stable patients: Proceed directly to contrast-enhanced CT chest 1
- High-velocity mechanisms (>35 mph MVC, rollover, ejection, motorcycle trauma, fall >15 feet): Consider whole-body CT with contrast 1
- Suspected aortic or major vessel injury: Obtain arterial phase CTA chest 1
Step 3: When to Use Plain CT
Only use plain CT if:
- Absolute contraindication to IV contrast exists 1
- Evaluating isolated sternal fracture with normal ECG and troponins 1, 2
- Patient has retained metal fragments requiring artifact reduction 1
Critical Pitfalls to Avoid
Never rely on chest radiograph alone to exclude thoracic injuries - studies show 40% of patients with "normal" chest radiographs had injuries on CT, and 29% with "abnormal" radiographs had no injury on CT. 1
Do not order plain CT when vascular assessment is needed - this delays definitive diagnosis and may miss life-threatening injuries like aortic dissection, cardiac rupture, or active hemorrhage. 1
Patients with abnormal chest radiograph in trauma have clinically significant rates of major injury on CT - proceed directly to contrast-enhanced CT rather than relying on plain films. 1
Special Considerations
Hemothorax or hemopericardium on plain CT warrants immediate contrast-enhanced study to identify the bleeding source and guide surgical intervention. 1
CT is more sensitive and specific than conventional radiographs regardless of contrast administration, but contrast provides the critical additional information about vascular integrity and active bleeding. 1
Ultrasound (FAST) has limited utility for comprehensive chest trauma evaluation due to lack of sensitivity for pulmonary, aortic, cardiac, and musculoskeletal injuries - it serves primarily as a triage tool for hemodynamically unstable patients. 1