What is the diagnostic workup for back pain?

Diagnostic Workup for Back Pain

The diagnostic workup for back pain should begin with a focused history and physical examination to categorize patients into one of three groups: nonspecific low back pain, back pain potentially associated with radiculopathy or spinal stenosis, or back pain potentially associated with another specific spinal cause. 1

Initial Assessment

History

• Location, frequency, and duration of pain
• Previous symptoms, treatments, and response
• Red flags for serious conditions:
  • History of cancer
  • Unexplained weight loss
  • Immunosuppression
  • Fever
  • Intravenous drug use
  • Significant trauma
  • Prolonged corticosteroid use
  • Age >70 years
• Neurological symptoms:
  • Radicular pain (sciatica)
  • Numbness or tingling
  • Weakness
  • Bowel or bladder dysfunction (urinary retention has 90% sensitivity for cauda equina syndrome) 1

Physical Examination

• Inspection of posture and gait
• Palpation of spine for tenderness
• Range of motion assessment
• Neurological examination:
  • Motor strength
  • Sensory testing
  • Deep tendon reflexes
  • Straight leg raise test (for radiculopathy)
• Assessment for psychosocial risk factors (predict chronic disabling back pain) 1

Diagnostic Testing

Imaging Guidelines

1. No imaging is recommended for nonspecific low back pain (strong recommendation, moderate-quality evidence) 1, 2

2. Immediate imaging is indicated only when these conditions are suspected:

   • Cauda equina syndrome
   • Progressive neurological deficits
   • Infection
   • Malignancy
   • Significant trauma 2

3. Delayed imaging (after 6 weeks of failed conservative management):

   • MRI without contrast is the preferred modality for persistent symptoms 2
   • CT scan if MRI is contraindicated or unavailable 1

4. Specialized imaging:

   • MRI with contrast for suspected infection, cancer, or in immunosuppressed patients 2
   • Plain radiographs for trauma, osteoporosis, elderly patients, or chronic steroid users 2

Laboratory Testing

• Not routinely indicated for nonspecific back pain
• Consider if infection or inflammatory condition is suspected:
  • Complete blood count
  • Erythrocyte sedimentation rate
  • C-reactive protein
  • Urinalysis (if urinary tract infection suspected)

Risk Stratification

The STarT Back tool is recommended at 2 weeks from pain onset to categorize patients into risk levels 2:

• Low risk: Encourage self-management
• Medium risk: Refer to physiotherapy with patient-centered plan
• High risk: Refer for comprehensive biopsychosocial assessment

Follow-Up and Referral Criteria

• Reassess within 48-72 hours if severe symptoms or red flags are present 2
• Consider specialist referral if:
  • Symptoms persist beyond 6 weeks despite appropriate management
  • Progressive neurological deficits
  • Suspected serious underlying condition
  • Potential candidate for surgery or epidural steroid injection 1

Special Considerations

• Elderly patients require slower progression of exercise intensity and careful medication management 2
• Patients with cardiovascular disease or renal impairment need special attention with NSAID use 2

Common Pitfalls to Avoid

• Ordering routine imaging for acute nonspecific back pain, which often reveals incidental findings in asymptomatic individuals 2
• Failing to recognize cauda equina syndrome, which requires emergency intervention
• Overlooking psychosocial factors that predict chronic disability
• Recommending bed rest rather than encouraging activity within pain limits 2

Remember that most cases of low back pain (>85%) are nonspecific and improve within 6-8 weeks with conservative management 1, 3. The primary goal of the diagnostic workup is to identify the small percentage of patients with serious underlying conditions requiring specific interventions.