What is the initial imaging of choice for a suspected pelvic fracture?

Initial Imaging for Suspected Pelvic Fractures

The initial imaging of choice for suspected pelvic fractures is an anteroposterior (AP) view of the pelvis with a cross-table lateral view of the symptomatic hip, which should be performed immediately for all patients with suspected pelvic trauma. 1

Imaging Protocol Based on Hemodynamic Status

Hemodynamically Unstable Patients

• Pelvic X-ray should be obtained immediately upon arrival to the trauma center for hemodynamically unstable patients 2
• Chest X-ray and Extended Focused Assessment with Sonography for Trauma (E-FAST) should be performed concurrently to rule out extra-pelvic causes of hemorrhagic shock 2
• These imaging modalities are compatible with ongoing resuscitation efforts and allow for rapid decision-making regarding bleeding control options 2
• Selective pelvic X-ray is associated with significant delays in recognition of major pelvic fractures, potentially delaying critical interventions like pelvic arterial embolization 3

Hemodynamically Stable Patients

• A thoraco-abdomino-pelvic CT scan with intravenous contrast should be performed instead of initial pelvic X-ray 2
• CT scanning provides a complete inventory of injuries and identifies active sources of bleeding 2
• The American College of Radiology recommends CT as the definitive imaging for stable patients with suspected pelvic fractures 1

Rationale for Comprehensive Imaging

• Patients with suspected proximal femur fracture often have concomitant fractures of the pelvis, including the sacrum and pubic rami 2, 1
• The inclusion of a pelvis radiograph allows for comparison of potential abnormalities to the contralateral asymptomatic side 2, 1
• Orthogonal views (AP and lateral) are essential for proper diagnosis and treatment planning 2
• Cross-table lateral views can change treatment decisions even when the AP view is clearly positive 2

Advanced Imaging for Occult Fractures

• Despite being the mainstay for initial imaging, pelvis and hip radiographs have limitations in sensitivity and specificity for fracture detection 2, 1
• When radiographs are negative but clinical suspicion remains high, MRI without IV contrast is the recommended next imaging study 2, 1
• CT scan is an alternative when MRI is contraindicated or unavailable, though it is less sensitive than MRI for detecting occult fractures 4, 5

Special Considerations for Vascular Injuries

• Contrast-enhanced CT can identify active arterial bleeding with a sensitivity of 84% and specificity of 85% 6
• Extravasation of contrast agent during the arterial phase of CT scan indicates arterial bleeding with sensitivities from 82% to 89% and specificities from 75% to 100% 2
• CT angiography should be performed before angiographic embolization in patients with severe pelvic trauma when allowed by the patient's hemodynamic status 2

Common Pitfalls to Avoid

• Relying solely on hip radiographs without including pelvis views may miss associated pelvic fractures 1
• Failing to obtain orthogonal views can lead to missed fractures and potentially altered treatment decisions 1
• Delaying imaging in unstable patients can increase mortality; time between admission and bleeding control procedures should not exceed 60 minutes 2
• Selective use of pelvic X-ray is associated with significant delays in recognition of pelvic fractures (48 minutes vs. 2 minutes with routine PXR) 3

Lower Urinary Tract Injury Assessment

• For patients with clinical symptoms of lower urinary tract injury (inability to urinate, gross hematuria, blood at the meatus, suprapubic tenderness), retrograde urethral and bladder opacification should be performed before attempting urinary catheterization, especially in men 2
• Contrast CT scan may miss bladder injuries, particularly intraperitoneal ruptures when a urinary catheter is already in place 2