What is the best treatment approach for a patient with a suspected psoas abscess and a negative medical history?

Management of Psoas Abscess in Patients with Negative Medical History

For patients with suspected psoas abscess and negative medical history, the optimal treatment approach is percutaneous catheter drainage (PCD) combined with appropriate antibiotic therapy targeting common causative organisms. 1

Diagnostic Approach

Clinical Assessment

• Look specifically for:
  • Fever, psoas spasm, and tender mass in the lower abdomen or flank
  • Hip pain or limitation of movement (psoas sign)
  • Symptoms may be nonspecific, requiring high index of suspicion

Laboratory Testing

• Complete blood count (CBC) - expect leukocytosis
• Inflammatory markers (C-reactive protein, ESR)
• Blood cultures before antibiotic initiation
• Serum glucose, HbA1c, and urine ketones to rule out undetected diabetes 2

Imaging

• CT scan with contrast is the gold standard for diagnosis
• MRI with DWI/ADC and T1 weighted imaging with and without gadolinium if available 3
• Ultrasound may be used initially but has lower sensitivity

Treatment Algorithm

Step 1: Assess Size and Accessibility

• Small abscesses (<3cm): May respond to antibiotics alone 3
• Larger abscesses (>3cm): Require drainage procedure

Step 2: Drainage Approach

• First-line: CT-guided percutaneous drainage for accessible abscesses 1, 4

  • Success rate of approximately 90% with percutaneous drainage 1
  • Lower complication rates compared to open surgical drainage 4

• Surgical drainage reserved for:

  • Failed percutaneous drainage
  • Inaccessible abscess location
  • Presence of complications (e.g., septic arthritis)
  • Multiloculated abscesses

Step 3: Antibiotic Therapy

• Empiric coverage should include:
  • Third-generation cephalosporin (e.g., ceftriaxone) plus metronidazole 3
  • Adjust based on culture and sensitivity results from abscess material
  • Duration: 4-6 weeks total (may transition to oral after clinical improvement)

Step 4: Monitoring Response

• Serial clinical examinations
• Follow-up imaging (CT or ultrasound) to confirm resolution
• Monitor inflammatory markers for treatment response

Special Considerations

Potential Complications

• Septic arthritis of the hip joint if abscess extends to periarticular tissue 5
• Recurrence (more common with antibiotic-only treatment)
• Sepsis in untreated cases

Underlying Causes

• Even with negative medical history, search for potential sources:
  • Occult gastrointestinal disease (especially Crohn's disease)
  • Spinal infections
  • Urological problems
  • Intravenous drug use (common cause of primary psoas abscess) 1

Follow-up

• Repeat imaging at 2-4 weeks after drainage to ensure resolution
• Investigate for underlying conditions if not previously identified
• Consider surgical intervention for recurrent abscesses

Pitfalls to Avoid

• Delaying drainage in patients with large abscesses
• Failing to obtain cultures before initiating antibiotics
• Missing underlying conditions that may lead to recurrence
• Premature removal of drainage catheters before complete resolution

The evidence strongly supports that most psoas abscesses can be successfully managed with percutaneous drainage and appropriate antibiotics, with surgery reserved for complicated cases or recurrences 1, 4.