What is the best initial imaging study to order for a patient presenting to the Emergency Department (ED) with left groin pain after a fall?

Best Initial Imaging for Patients with Left Groin Pain After a Fall

For a patient presenting to the Emergency Department with left groin pain after a fall, radiography of the pelvis and hip (AP pelvis view plus cross-table lateral view of the affected hip) should be the initial imaging study ordered. 1

Rationale for Initial Imaging Selection

The American College of Radiology Appropriateness Criteria provides clear guidance on this common clinical scenario:

• Radiographs are rapidly obtained, well-tolerated by patients, and cost-effective
• When a fracture is demonstrated on initial radiographs, frequently no additional imaging is needed for treatment planning 1
• Standard views include:
  • Anteroposterior (AP) view of the pelvis
  • Cross-table lateral view of the symptomatic hip

Why Include Both Pelvis and Hip Views?

• Patients with suspected proximal femur fracture often have concurrent fractures of the pelvis (including sacrum and pubic rami)
• Pelvic fractures may occur in isolation or alongside proximal femur fractures
• The pelvis view allows comparison with the contralateral asymptomatic side 1

When Initial Radiographs Are Negative

If initial radiographs are negative but clinical suspicion for fracture remains high:

1. MRI without contrast is the recommended next study

   • Nearly 100% sensitivity for detecting occult fractures 1
   • Can identify both femoral and pelvic fractures
   • Can detect associated soft tissue injuries
   • A negative MRI may allow confident discharge from the ED 1

2. CT scan is an alternative when MRI is unavailable

   • Less sensitive than MRI but can detect most occult fractures
   • Useful for better depicting fracture morphology for treatment planning 1

Clinical Pearls and Pitfalls

Important Clinical Considerations:

• Hip fractures may present with vague symptoms beyond just hip pain, including pain in the buttocks, knees, thighs, groin, or back 2
• Some patients with hip fractures may initially be able to walk and have no typical deformity 2
• Occult fractures are more common in elderly patients with osteoporosis 3

Common Pitfalls to Avoid:

• Relying solely on negative initial radiographs to rule out fracture - approximately 10% of hip fractures are not visible on initial radiographs 1
• Failing to consider insufficiency fractures of the pelvis in elderly patients with osteopenia, which can mimic other conditions 3
• Missing basicervical femoral neck fractures, which may only be visible on MRI despite normal radiographs, as demonstrated in the AAOS guidelines 1

Special Considerations

• In patients with osteoporosis or rheumatoid arthritis, pubic symphysis fractures should be considered as a potential cause of groin pain after minor trauma 4
• Delays in diagnosis and treatment of hip fractures are associated with increased morbidity, mortality, and healthcare costs 2

By following this evidence-based approach to imaging for patients with left groin pain after a fall, clinicians can efficiently diagnose fractures and provide timely, appropriate treatment to minimize complications and improve outcomes.