Treatment of Acute Diverticulitis
The treatment of acute diverticulitis should be tailored to disease severity, with uncomplicated diverticulitis often managed with outpatient care and antibiotics, while complicated diverticulitis requires more aggressive intervention including percutaneous drainage for abscesses >4-5 cm and surgical management for peritonitis. 1
Classification and Initial Assessment
Disease severity determines treatment approach:
- Uncomplicated diverticulitis: Localized inflammation without abscess, perforation, or peritonitis
- Complicated diverticulitis: Presence of abscess, perforation, fistula, or peritonitis
Key assessment factors:
- Vital signs (fever, tachycardia)
- Laboratory markers (WBC, CRP)
- CT imaging findings (extent of inflammation, presence of abscess, extraluminal gas)
Treatment Algorithm Based on Disease Severity
1. Uncomplicated Diverticulitis
Outpatient management is appropriate for patients with:
- Mild symptoms
- Ability to tolerate oral intake
- No significant comorbidities
- Adequate social support
Antibiotic therapy:
2. Diverticulitis with Small Abscess (<4-5 cm)
- Antibiotic therapy alone is considered safe and effective 1, 3
- Pooled failure rate of approximately 20% with mortality rate of 0.6% 1
- Close monitoring for clinical improvement is essential
- Consider hospitalization if:
- Significant pain
- Unable to tolerate oral intake
- Comorbidities
- Signs of systemic infection
3. Diverticulitis with Large Abscess (>4-5 cm)
- Percutaneous drainage combined with antibiotic therapy is recommended 1
- If percutaneous drainage is not feasible:
- Antibiotic therapy alone with careful monitoring
- Surgical intervention if clinical deterioration occurs
- Drainage catheter management:
- Remove when output ceases or decreases substantially
- Consider CT with contrast via catheter before removal
- Consider further drainage or surgery if no improvement
4. Diverticulitis with Pericolic Gas
- Trial of non-operative treatment with antibiotics is suggested 1
- Monitor closely for signs of deterioration
- CRP level at presentation is a predictor of treatment failure
5. Diverticulitis with Diffuse Peritonitis
- Surgical intervention is required
- Antibiotic therapy:
- Cover gram-positive, gram-negative, and anaerobic bacteria
- Consider ESBL coverage for patients with risk factors (prior antibiotic exposure, comorbidities requiring concurrent antibiotics)
- 4-day duration post-source control is sufficient 1
Antibiotic Selection
- Uncomplicated diverticulitis: Oral antibiotics covering gram-negative and anaerobic bacteria
- Complicated diverticulitis: Initial IV antibiotics with broad spectrum coverage
Monitoring and Follow-up
- Clinical improvement should be seen within 2-3 days
- Lack of improvement warrants reassessment and possible escalation of care
- Follow-up imaging is not routinely needed for uncomplicated cases with clinical improvement
- Colonoscopy is recommended 4-6 weeks after resolution for patients with complicated diverticulitis to exclude malignancy 1
Pitfalls and Caveats
Failure to recognize deterioration: Patients initially managed conservatively should be monitored for signs of clinical deterioration requiring more aggressive intervention.
Overuse of antibiotics: Evidence suggests antibiotics may not be necessary for all cases of uncomplicated diverticulitis 2.
Inadequate drainage of large abscesses: Abscesses >4-5 cm generally require drainage as antibiotics alone may fail to reach adequate concentration inside the abscess 1.
Missing underlying malignancy: Colonic evaluation should be performed after resolution of complicated diverticulitis to exclude malignancy 1.
Prolonged antibiotic therapy: Extended courses beyond 4 days after adequate source control have not shown benefit 1.
The management of acute diverticulitis has evolved toward more conservative approaches, with increasing evidence supporting outpatient management for uncomplicated cases 4, 5 and targeted interventions based on disease severity for complicated cases.