What is the treatment for a psoas abscess?

Treatment of Psoas Abscess

The treatment of psoas abscess requires a combination of appropriate antibiotic therapy and drainage of the abscess, with percutaneous drainage under imaging guidance being the first-line approach for most cases. 1, 2

Diagnostic Approach

• Psoas abscess typically presents with fever, psoas spasm, a tender mass, and leukocytosis 3
• Imaging studies are essential for diagnosis:
  • CT scan with IV contrast is the preferred imaging modality 4
  • Ultrasound can also be used for initial evaluation 4
  • MRI may be helpful in some cases 3

Treatment Algorithm

Step 1: Drainage

• Percutaneous catheter drainage (PCD) under imaging guidance is the first-line treatment 1, 2
• Surgical drainage options should be considered if PCD fails or is not feasible:
  • Laparoscopic drainage offers complete evacuation with minimal invasiveness 1
  • Open surgical drainage may be necessary for complex or multiloculated abscesses 3

Step 2: Antibiotic Therapy

• Empiric broad-spectrum antibiotic therapy should be initiated immediately after obtaining cultures 5
• Initial antibiotic regimen should include:
  • Coverage for MRSA (such as vancomycin or daptomycin) 4
  • Coverage for Gram-negative bacteria (third-generation cephalosporin) 4
  • Coverage for anaerobic bacteria (metronidazole) 4
• Recommended empiric regimen:
  • Third-generation cephalosporin plus metronidazole 4
  • Alternative: Meropenem for broader coverage 4

Step 3: Duration and Adjustment of Therapy

• Antibiotic therapy should be adjusted based on culture results 5
• Duration of antibiotic therapy:
  • For uncomplicated cases with adequate drainage: 4-7 days 4
  • For immunocompromised or critically ill patients: up to 7 days 4
  • For complex cases or inadequate drainage: 2-6 weeks 4

Special Considerations

Primary vs. Secondary Psoas Abscess

• Primary psoas abscess has no definite etiology and is spread hematogenously 2, 6
  • Most commonly caused by Staphylococcus aureus 6
• Secondary psoas abscess is due to direct spread from adjacent structures 2, 3
  • Common causes include Crohn's disease, appendicitis, diverticulitis, and carcinoma 2, 7
  • Treatment should address the underlying cause (e.g., bowel resection for Crohn's disease) 7

Immunocompromised Patients

• In severely immunocompromised patients, consider broader antimicrobial coverage 4
• HIV patients may benefit from less invasive drainage approaches 6

Monitoring and Follow-up

• Regular assessment of local and systemic signs of infection 5
• Patients with ongoing signs of infection beyond 7 days warrant further diagnostic investigation 4
• Follow-up imaging may be necessary to ensure complete resolution 1

Potential Complications

• Septic shock and neurological deficits 1
• Thromboembolic complications (reported in 8.3% of cases with Crohn's disease) 7
• Recurrence if underlying cause is not addressed 3

By following this structured approach to diagnosis and treatment, the management of psoas abscess can be optimized to reduce morbidity and mortality while improving quality of life outcomes.