Treatment of Diverticulitis
For otherwise healthy adults with uncomplicated diverticulitis (no abscess, perforation, peritonitis, or sepsis), observation with supportive care alone—without antibiotics—is the recommended first-line approach. 1
Initial Diagnostic Confirmation
- CT scan with IV contrast is mandatory to verify uncomplicated disease (no abscess ≥4 cm, no perforation, no fistula, no obstruction) before withholding antibiotics. 1, 2
- CT has 98–99% sensitivity and 99–100% specificity for acute diverticulitis. 2
First-Line Management: Observation Without Antibiotics
Most immunocompetent patients with uncomplicated diverticulitis do NOT require antibiotics. 1, 2
- Multiple high-quality randomized trials (including the DIABOLO trial with 528 patients) demonstrate that antibiotics neither accelerate recovery nor prevent complications or recurrence in uncomplicated cases. 1
- Supportive care includes:
- If diet cannot be advanced within 3–5 days, prompt reassessment is required. 1
When to Add Antibiotics: High-Risk Features
Reserve antibiotics for patients with ANY of the following criteria: 1, 2
Clinical Indicators
- Persistent fever >100.4°F or chills despite supportive care. 1
- Refractory symptoms or vomiting. 1, 2
- Inability to maintain oral hydration. 1, 2
- Symptom duration >5 days before presentation. 1
Laboratory Markers
CT Findings
- Fluid collection or small abscess (<4 cm). 1
- Extensive segment of inflammation. 1
- Pericolic extraluminal air. 1
Patient Factors
- Immunocompromised status (chemotherapy, high-dose steroids, organ transplant). 1, 2
- Age >80 years. 1, 2
- Pregnancy. 1, 2
- Significant comorbidities: cirrhosis, chronic kidney disease, heart failure, poorly controlled diabetes. 1, 2
- ASA physical status III–IV. 1
Antibiotic Regimens When Indicated
Outpatient Oral Therapy (4–7 Days for Immunocompetent Patients)
- Amoxicillin-clavulanate 875/125 mg PO twice daily (validated in the DIABOLO trial). 1, 2
- Ciprofloxacin 500 mg PO twice daily PLUS metronidazole 500 mg PO three times daily (alternative regimen). 1, 2
Outpatient eligibility requires ALL of the following: 1
- Ability to tolerate oral fluids and medications. 1, 4
- No significant comorbidities or frailty. 1, 4
- Reliable home/social support. 1, 4
- Temperature <100.4°F. 1
- Pain controlled with acetaminophen alone (pain score <4/10). 1
Inpatient IV Therapy (Transition to Oral Within ≈48 Hours)
Indications for hospitalization: 1, 2
- Inability to tolerate oral intake. 1, 2
- Severe systemic symptoms or signs of sepsis. 1, 2
- Significant comorbidities/frailty. 1, 2
- Immunocompromised status. 1, 2
- Ceftriaxone PLUS metronidazole. 1, 2
- Piperacillin-tazobactam 4 g/0.5 g IV q6h (provides complete gram-negative and anaerobic coverage as monotherapy; metronidazole is unnecessary). 3, 5
- Cefuroxime PLUS metronidazole (alternative). 3, 2
Transition to oral antibiotics as soon as the patient tolerates oral intake (typically within 48 hours) to facilitate earlier discharge. 1
Duration of Therapy
- Immunocompetent patients: 4–7 days total (IV → oral). 1, 3
- Immunocompromised patients: 10–14 days total. 1, 3
- After percutaneous drainage of abscess: continue oral antibiotics for 4 days post-source control. 1, 5
Management of Complicated Diverticulitis
Small Abscess (<4–5 cm)
Large Abscess (≥4–5 cm)
- CT-guided percutaneous drainage PLUS IV antibiotics for 4 days after adequate source control. 1, 6, 7
- Cultures from drainage guide antibiotic selection. 1
Generalized Peritonitis or Sepsis
- Emergent surgical consultation for source control (Hartmann procedure or primary resection with anastomosis). 1, 2, 7
- Broad-spectrum IV antibiotics immediately: piperacillin-tazobactam, meropenem, or ceftriaxone plus metronidazole. 1, 5, 2
Follow-Up and Monitoring
- Mandatory re-evaluation within 7 days (earlier if symptoms worsen). 1
- If symptoms persist after 5–7 days of antibiotics, obtain repeat CT scan to rule out complications (abscess, perforation). 1
- Colonoscopy 6–8 weeks after symptom resolution for first episode of uncomplicated diverticulitis (if no recent high-quality colonoscopy), any complicated episode (7.9% associated cancer risk), or patients >50 years needing routine screening. 1, 7
Prevention of Recurrence
Lifestyle modifications reduce recurrence risk: 1
- High-fiber diet (≥22 g/day from fruits, vegetables, whole grains, legumes) combined with low intake of red meat and sweets. 1
- Regular vigorous physical activity. 1
- Maintain normal BMI (18–25 kg/m²). 1
- Smoking cessation. 1
- Avoid nonaspirin NSAIDs when possible. 1
Do NOT restrict nuts, corn, popcorn, or small-seeded fruits—they are not linked to increased diverticulitis risk. 1
Do NOT prescribe mesalamine or rifaximin for prevention; high-certainty evidence shows no benefit. 1
Common Pitfalls to Avoid
- Routine antibiotic use in uncomplicated disease without high-risk features adds to antimicrobial resistance without clinical benefit. 1
- Failing to obtain CT confirmation before withholding antibiotics; all studies supporting observation required imaging to rule out complications. 1
- Applying the "no antibiotics" approach to complicated diverticulitis (Hinchey 1b or higher with abscess formation); the evidence specifically excluded these patients. 1
- Assuming all patients require hospitalization; most can be safely managed as outpatients with appropriate follow-up, resulting in 35–83% cost savings. 1
- Adding metronidazole to piperacillin-tazobactam; this provides no additional benefit because anaerobic coverage is already complete. 3
Special Populations
Immunocompromised Patients
- Require immediate antibiotic therapy (10–14 days), a lower threshold for repeat CT imaging, and early surgical consultation regardless of other factors. 1, 3
- Corticosteroid use specifically increases the risk of perforation and death. 1