Imaging Approach for Blunt Trauma with Lower Extremity Fracture and Facial Laceration
This patient requires whole-body CT (WBCT) with IV contrast given the high-energy mechanism (tree falling on patient with ejection force), obvious lower extremity fracture, and facial trauma, along with initial trauma series radiographs and extremity films. 1
Initial Imaging Sequence
Start with trauma series radiographs consisting of portable AP chest and pelvis films to screen for immediate life-threatening findings like tension pneumothorax, significant mediastinal injury, unstable pelvic fractures, and to confirm line placement. 1 Simultaneously obtain radiographs of the fractured lower left extremity as these are first-line examination for suspected extremity injuries and take minimal time. 1
Perform FAST ultrasound primarily for triage purposes—a positive FAST with hemodynamic instability may necessitate immediate surgical intervention rather than proceeding to CT. 1 However, FAST's lower specificity compared to CT means it cannot exclude injuries, so negative FAST should not prevent definitive imaging. 1
Whole-Body CT Protocol
Proceed with WBCT with IV contrast (chest, abdomen, pelvis) in the portal venous phase (70 seconds post-contrast) as this patient meets high-risk criteria: high-energy mechanism (tree falling with sufficient force to cause ejection), obvious extremity fracture suggesting significant force transmission, and facial trauma raising concern for occult injuries. 1
The mechanism of a tree falling on the patient with subsequent ejection represents high-energy blunt trauma analogous to falls from height >15 feet, which is a specific indication for WBCT over selective imaging. 1 While meta-analyses show conflicting mortality benefits for WBCT versus selective CT, the high-energy mechanism and multiple body regions involved (extremity, face, potential torso) justify comprehensive imaging. 1
Contrast-enhanced CT has significantly greater sensitivity for detecting visceral organ and vascular injury compared to noncontrast CT and should be primarily considered unless absolutely contraindicated. 1 Avoid oral contrast as it delays diagnosis without improving sensitivity for blunt trauma. 1
Extremity-Specific Imaging
Consider CT angiography (CTA) of the lower extremity during the same acquisition if there is clinical suspicion for arterial injury (absent pulses, expanding hematoma, bruit, or hard signs of vascular injury). 1 CTA can be obtained during the same contrast bolus as the body imaging. 1
CT of the fractured extremity without contrast provides superior characterization of complex fracture patterns compared to radiographs alone, which is critical for surgical planning. 1, 2 This is particularly important for comminuted or displaced fractures where CT identifies fracture complexity that changes surgical management. 1
Facial Trauma Imaging
CT maxillofacial without contrast should be included in the WBCT protocol to evaluate the chin laceration for underlying mandibular or facial bone fractures. 1 CT is nearly 100% sensitive for mandibular fractures with improved interobserver agreement compared to radiographs, and identifies fractures not visible on plain films. 1
Do not obtain dedicated facial radiographs (panorex or mandible series) in this acute polytrauma setting—CT provides superior sensitivity (92% vs 66% for mandible series) and evaluates for associated injuries simultaneously. 1 Multiplanar and 3D reconstructions from CT are critical for surgical planning of complex facial fractures. 1
Critical Pitfalls to Avoid
Do not perform routine "pan-scan" protocols that scan body regions multiple times—use single-phase contrast to minimize radiation while maintaining diagnostic quality. 1 However, this high-energy mechanism patient is NOT a candidate for selective imaging. 1
Do not delay CT imaging for extensive plain film series beyond the initial trauma radiographs (chest, pelvis, extremity). 1 Time to definitive imaging impacts outcomes in polytrauma.
Ensure hemodynamic stability before CT—if patient becomes unstable with positive FAST, proceed directly to operating room rather than CT. 1 The FAST serves as a decision point, not a diagnostic endpoint.
Consider cervical spine imaging given the mechanism (axial loading from tree falling, potential for ejection injury). While not explicitly mentioned in your question, falls from height and high-energy mechanisms warrant cervical spine clearance. 1
Follow-Up Imaging Considerations
Clinical symptoms should drive any follow-up imaging after discharge (new abdominal distention, fever, worsening pain). 1 For adults, CT is the first-line follow-up tool for new symptoms. 1
Repeat extremity radiographs in 10-14 days if there is concern for radiographically occult fractures not identified on initial imaging, though CT at initial presentation has high sensitivity (88-98% specificity) for fracture detection. 2