What is the treatment for abdominal diverticular abscess?

Treatment of Abdominal Diverticular Abscess

For abdominal diverticular abscesses, the treatment approach should be based on abscess size, with small abscesses (<4-5 cm) managed with antibiotics alone for 7 days and large abscesses (≥4-5 cm) requiring percutaneous drainage combined with antibiotics for 4 days. 1, 2

Initial Assessment and Diagnosis

• Imaging: CT scan with IV contrast is the preferred diagnostic test (98% sensitivity, 99% specificity) 2
• Key findings on imaging:
  • Intestinal wall thickening
  • Signs of inflammation in pericolonic fat
  • Thickening of lateroconal fascia
  • Pericolonic or distant abscess 1
• Laboratory markers:
  • Increased white blood cell count
  • Leukocyte shift to left (>75%)
  • Elevated C-reactive protein
  • Procalcitonin 1

Treatment Algorithm Based on Abscess Size

Small Diverticular Abscesses (<4-5 cm)

1. Antibiotic therapy alone for 7 days 1, 2
2. Antibiotic options:
   • Immunocompetent, non-critically ill patients:
     • Piperacillin/tazobactam 4g/0.5g q6h 1, 3
     • Ertapenem 1g q24h 1
     • Eravacycline 1 mg/kg q12h 1
   • For beta-lactam allergies:
     • Eravacycline 1 mg/kg q12h or Tigecycline 100 mg loading dose then 50 mg q12h 1

Large Diverticular Abscesses (≥4-5 cm)

1. Percutaneous drainage combined with antibiotic therapy for 4 days 1, 2
   • CT-guided drainage is most common (83% of cases) 4
   • Mean duration of drainage is approximately 8 days 4
2. Antibiotic options: Same as for small abscesses

Special Considerations

When Percutaneous Drainage Is Not Feasible

• For non-critically ill, immunocompetent patients: Antibiotics alone may be considered 1, 5
• For critically ill or immunocompromised patients: Surgical intervention should be considered 1

Critically Ill or Immunocompromised Patients

• Extended antibiotic therapy up to 7 days based on clinical condition and inflammatory markers 1
• Antibiotic options:
  • Piperacillin/tazobactam 6g/0.75g loading dose then 4g/0.5g q6h or 16g/2g by continuous infusion 1, 3
  • Eravacycline 1 mg/kg q12h 1
  • For septic shock: Meropenem 1g q6h, Doripenem 500mg q8h, or Imipenem/cilastatin 500mg q6h (all by extended or continuous infusion) 1

Monitoring and Follow-up

• Monitor for treatment failure: Persistent symptoms, worsening clinical condition
• Failure rates:
  • Antibiotics alone: approximately 25% may require urgent surgery 5
  • Percutaneous drainage: approximately 18% may require urgent surgery 5
• Ongoing signs of infection beyond 7 days warrant further diagnostic investigation 1

Surgical Management

• Indications for surgery:
  • Failure of percutaneous drainage
  • Peritonitis
  • Fistula formation
  • Bowel obstruction 2
• Surgical options:
  • Primary resection and anastomosis with/without diverting stoma (stable patients)
  • Hartmann's procedure (critically ill patients or those with multiple comorbidities) 1

Emerging Approaches

• Endoscopic ultrasound (EUS)-guided drainage with lumen-apposing metal stents shows promise for pelvic abscesses >4cm close to the colonic wall 6
  • Technical and clinical success rates of approximately 88.8% 6
  • May avoid radiologic intervention or surgery in selected cases

Pitfalls to Avoid

1. Inadequate antibiotic selection: Only 23% of patients receive appropriate antibiotics at optimal concentrations 7
2. Inadequate monitoring: Patients with persistent symptoms need reassessment
3. Delayed drainage: Large abscesses require prompt drainage for optimal outcomes
4. Missing underlying malignancy: Consider colonoscopy 4-6 weeks after resolution of complicated diverticulitis 2

By following this evidence-based approach to diverticular abscesses, clinicians can optimize outcomes while minimizing morbidity and mortality associated with this common complication of diverticulitis.