What are the concerns and appropriate imaging for a patient presenting to the ER with a large right gluteal abscess?

Management of Large Right Gluteal Abscess in the Emergency Department

CT imaging with IV contrast is the recommended first-line imaging modality for patients presenting to the ER with a large right gluteal abscess, followed by prompt surgical incision and drainage guided by the imaging findings. 1, 2

Key Concerns with Gluteal Abscesses

• Sepsis risk: Large abscesses can lead to systemic infection and septic shock if not properly managed
• Underlying etiology: May indicate serious conditions such as:
  • Crohn's disease with fistula formation 3, 4
  • Diverticulitis with extension 2
  • Immunocompromised state 5, 6
  • Post-surgical complication 7
• Extension of infection: Potential spread to adjacent structures including:
  • Pelvic cavity
  • Piriformis muscle
  • Presacral space
  • Sciatic nerve involvement (causing sciatica) 6

Appropriate Imaging Protocol

First-Line Imaging:

• CT scan with IV contrast 1, 2
  • Coverage should extend from lower abdomen through entire perineum
  • Slice thickness of 2-3mm
  • IV contrast is essential to delineate rim enhancement of abscess and identify fistulous tracts
  • Timing: contrast-enhanced imaging 50-70 seconds after IV contrast injection

CT Advantages:

• Widely available in emergency settings
• Short acquisition time
• Can identify:
  • Abscess size, location, and extent
  • Multiloculation (predicts drainage failure)
  • Underlying causes (diverticulitis, Crohn's disease)
  • Fistulous tracts
  • Relationship to adjacent structures

Alternative/Additional Imaging:

• MRI: Superior for complex fistula evaluation but limited availability in emergency settings 2, 1
• Point-of-care ultrasound: May be used when CT is unavailable to confirm fluid collection 2

Management Approach

1. Assess for sepsis: Determine timing of intervention based on sepsis severity 2

2. Antibiotic therapy:

   • Start empiric antibiotics covering gram-negative bacteria and anaerobes 2
   • Adjust based on culture results
   • Continue antibiotics after drainage

3. Surgical drainage:

   • Primary treatment is surgical incision and drainage 2
   • For abscesses >3-4cm, surgical drainage is essential 2
   • Timing based on sepsis severity 2

4. Special considerations:

   • If abscess >5cm or multiloculated, surgical drainage is preferred over percutaneous drainage 2
   • For abscesses associated with Crohn's disease, consider both drainage and treatment of underlying disease 3

Common Pitfalls to Avoid

• Inadequate imaging: Failing to use IV contrast can reduce diagnostic accuracy 1
• Incomplete drainage: Associated with high recurrence rates (up to 44%) 2
• Missing underlying cause: Failure to identify and treat conditions like Crohn's disease or diverticulitis 3, 2
• Delayed intervention: Especially in immunocompromised patients who may present with minimal symptoms despite severe infection 5, 6
• Overlooking fistulous tracts: Can lead to recurrence if not identified and addressed 4

Follow-up Recommendations

• Routine imaging after successful drainage is usually not required
• Consider follow-up imaging in cases of:
  • Recurrence
  • Suspected inflammatory bowel disease
  • Evidence of fistula formation
  • Non-healing wound 2

By following this approach, you can effectively diagnose and manage patients presenting with large gluteal abscesses while minimizing complications and recurrence.