Should a computed tomography (CT) scan be ordered immediately for a patient presenting with back pain?

CT Scanning for Back Pain: When to Order

CT scans should not be ordered immediately for patients presenting with back pain unless specific "red flag" symptoms are present. 1

Initial Approach to Back Pain

When evaluating a patient with back pain, imaging should be guided by the presence or absence of clinical red flags:

Red Flags Requiring Immediate Imaging

• Trauma with suspected fracture
• Suspected malignancy (history of cancer, unexplained weight loss, pain worse at night)
• Suspected infection (fever, IV drug use, immunosuppression)
• Neurological deficits (progressive motor weakness, cauda equina syndrome)
• Age >70 with first episode of back pain

Appropriate Initial Imaging Selection

1. For patients WITHOUT red flags:

   • No immediate imaging is indicated 1
   • Conservative management for 4-6 weeks is recommended
   • Imaging during this period does not improve clinical outcomes 2

2. For patients WITH red flags:

   • MRI without contrast is the preferred initial imaging modality for most red flags 1
   • CT without contrast may be appropriate in specific situations:
     • Suspected fracture following trauma
     • When MRI is contraindicated or unavailable
     • For detailed bone evaluation (e.g., suspected spondylolysis)

CT vs. MRI for Back Pain

When CT is Appropriate

• Suspected fracture or bone abnormality
• Contraindications to MRI (pacemaker, metal implants)
• Evaluation of osseous tumors (e.g., osteoid osteoma) 1
• In prostate cancer patients with suspected bone metastases 3

When MRI is Preferred

• Suspected disc herniation (CT has only 55% sensitivity) 4
• Suspected infection or inflammation 1
• Evaluation of spinal cord, nerve roots, or soft tissues
• Suspected malignancy with potential epidural extension 1

Common Pitfalls to Avoid

1. Overutilization of imaging:

   • Studies show imaging is performed in approximately 33.7% of emergency department visits for low back pain, despite guidelines recommending against routine imaging 5
   • Unnecessary imaging increases costs and radiation exposure without improving outcomes

2. Misinterpretation of incidental findings:

   • Anatomical abnormalities are common in asymptomatic individuals
   • Findings on imaging may not correlate with clinical symptoms

3. Relying solely on imaging for diagnosis:

   • Back pain is often multifactorial
   • Imaging findings must be correlated with clinical presentation

Algorithm for Imaging Decision-Making

1. Assess for red flags
2. If no red flags present → conservative management for 4-6 weeks
3. If red flags present → select appropriate imaging:
   • Suspected fracture → CT without contrast
   • Suspected disc, soft tissue, or neurological involvement → MRI without contrast
   • Suspected infection or tumor → MRI without and with contrast
4. If symptoms persist after conservative management → consider MRI

By following these evidence-based guidelines, clinicians can avoid unnecessary imaging while ensuring appropriate evaluation of potentially serious conditions.