Management of Acute Diverticulitis
For immunocompetent adults with acute uncomplicated diverticulitis, observation with supportive care alone—without routine antibiotics—is the recommended first-line approach. 1, 2, 3
Initial Diagnostic Confirmation
- Obtain CT abdomen/pelvis with IV contrast to confirm diverticulitis and distinguish uncomplicated from complicated disease (98–99% sensitivity, 99–100% specificity). 4, 5
- Order complete blood count and C-reactive protein to assess inflammatory burden and identify high-risk features. 4, 5
- Classify as uncomplicated (localized inflammation only) or complicated (abscess, perforation, fistula, obstruction, or bleeding). 2, 6, 5
Outpatient Management for Uncomplicated Diverticulitis
Patient Selection Criteria (All Must Be Met)
- CT-confirmed uncomplicated disease (no abscess, perforation, fistula, or obstruction). 1, 2
- Ability to tolerate oral fluids and medications. 1, 2
- Temperature <100.4°F (38°C). 1
- Pain controlled with acetaminophen alone (pain score <4/10). 1
- No significant comorbidities (cirrhosis, chronic kidney disease, heart failure, poorly controlled diabetes). 1, 2
- Immunocompetent status (no chemotherapy, high-dose steroids, or organ transplant). 1, 5
- Adequate home/social support. 1, 2
Supportive Care Protocol (No Antibiotics)
- Clear liquid diet for 2–3 days, then advance as tolerated. 1, 2
- Acetaminophen 1 gram three times daily for pain (avoid NSAIDs). 1, 5
- Adequate oral hydration. 1, 2
- Mandatory re-evaluation within 7 days (or sooner if symptoms worsen). 1, 2
Evidence: The DIABOLO trial (528 patients) and AVOD study demonstrated that antibiotics do not accelerate recovery, prevent complications, or reduce recurrence in uncomplicated diverticulitis; hospital stays were actually shorter without antibiotics (2 vs 3 days, p=0.006). 1, 7, 3
Selective Antibiotic Use: High-Risk Features
Reserve antibiotics for patients with ANY of the following:
Clinical Indicators
- Persistent fever >100.4°F or chills despite supportive care. 1, 5
- Refractory symptoms or vomiting. 1, 5
- Inability to maintain oral hydration. 1, 5
- Symptom duration >5 days before presentation. 4, 1
Laboratory Markers
- C-reactive protein >140 mg/L. 4, 1, 5
- White blood cell count >15 × 10⁹/L or rising leukocytosis. 4, 1, 5
CT Findings
- Fluid collection or abscess. 4, 1
- Longer segment of colonic inflammation. 4, 1
- Pericolic extraluminal air. 4, 1
Patient Factors
- Immunocompromised status (chemotherapy, high-dose steroids, organ transplant). 4, 1, 5
- Age >80 years. 4, 1, 5
- Pregnancy. 4, 1, 5
- ASA physical status III–IV. 4, 1
- Significant comorbidities or frailty (cirrhosis, CKD, heart failure, poorly controlled diabetes). 4, 1, 5
Antibiotic Regimens When Indicated
Outpatient Oral Therapy (4–7 Days for Immunocompetent)
- First-line: Amoxicillin-clavulanate 875/125 mg PO twice daily. 1, 5
- Alternative: Ciprofloxacin 500 mg PO twice daily PLUS metronidazole 500 mg PO three times daily. 4, 1, 5
Inpatient IV Therapy (Transition to Oral Within 48 Hours)
- Ceftriaxone PLUS metronidazole OR piperacillin-tazobactam. 4, 1, 5
- Switch to oral antibiotics as soon as patient tolerates oral intake. 1
Duration
Indications for Hospital Admission
- Complicated diverticulitis on CT (abscess ≥4–5 cm, perforation, fistula, obstruction). 1, 2, 5
- Inability to tolerate oral intake. 1, 2
- Signs of sepsis or systemic inflammatory response. 1, 5
- Immunocompromised status. 1, 5
- Significant comorbidities or frailty. 1, 2
Management of Complicated Diverticulitis
Small Abscess (<4–5 cm)
Large Abscess (≥4–5 cm)
- CT-guided percutaneous drainage PLUS IV antibiotics. 1, 2, 5
- Continue antibiotics for 4 days post-drainage in immunocompetent patients. 1
Generalized Peritonitis or Sepsis
- Emergent surgical consultation for source control (Hartmann procedure or primary resection with anastomosis). 1, 5
- Immediate broad-spectrum IV antibiotics (piperacillin-tazobactam or ceftriaxone plus metronidazole). 1, 5
Post-Acute Management
Colonoscopy Timing
- Schedule colonoscopy 6–8 weeks after symptom resolution for:
Recurrence Prevention
- High-fiber diet (≥22 g/day from fruits, vegetables, whole grains, legumes). 4, 1, 6
- Regular vigorous physical activity. 4, 1
- Maintain BMI 18–25 kg/m². 4, 1
- Smoking cessation. 4, 1
- Avoid nonaspirin NSAIDs when possible. 4, 6
- Do NOT restrict nuts, corn, popcorn, or small-seeded fruits (no evidence of increased risk). 4, 1, 6
Special Populations
Immunocompromised Patients
- Immediate antibiotic therapy for 10–14 days. 4, 1
- Lower threshold for CT imaging and surgical consultation. 4, 1
- May present with milder symptoms despite more severe disease. 4
Elderly Patients (>65 Years)
- Lower threshold for antibiotic treatment even with localized disease. 1
- Age >80 years is an independent indication for antibiotics. 4, 1, 5
Critical Pitfalls to Avoid
- Do NOT prescribe routine antibiotics for uncomplicated diverticulitis without high-risk features—this contributes to antimicrobial resistance without clinical benefit. 1, 2, 8
- Do NOT assume all patients require hospitalization—most immunocompetent patients with uncomplicated disease can be safely managed outpatient with 35–83% cost savings. 1, 2, 9
- Do NOT discharge patients without CT confirmation of uncomplicated disease. 1
- Do NOT overlook immunocompromised patients—they require immediate antibiotics (10–14 days), lower threshold for repeat imaging, and early surgical consultation. 4, 1
- Do NOT stop antibiotics early if indicated—complete the full course to prevent recurrence. 1
- Do NOT perform colonoscopy during acute inflammation—wait 6–8 weeks to avoid perforation risk. 4
- Do NOT prescribe mesalamine or rifaximin for prevention—strong evidence shows no benefit. 4, 6
Follow-Up Protocol
- Re-evaluate within 7 days of initial diagnosis (earlier if symptoms worsen). 1, 2
- Instruct patients to return immediately for: fever >101°F, severe uncontrolled pain, persistent vomiting, inability to eat/drink, or signs of dehydration. 1
- Obtain repeat CT if symptoms persist beyond 5–7 days despite appropriate management. 1