What is the recommended treatment for diverticulitis?

Treatment of Diverticulitis

For immunocompetent patients with uncomplicated diverticulitis, observation without antibiotics is the recommended first-line approach, consisting of clear liquid diet and pain control with acetaminophen. 1, 2, 3

Initial Assessment and Classification

Uncomplicated diverticulitis is defined as localized diverticular inflammation without abscess, perforation, fistula, or obstruction, confirmed by CT scan showing diverticula, wall thickening, and increased pericolic fat density. 2, 3 CT scan has 98-99% sensitivity and 99-100% specificity for diagnosis. 4

Complicated diverticulitis involves abscess formation, perforation, fistula, or obstruction and requires more aggressive management. 3, 4

Treatment Algorithm for Uncomplicated Diverticulitis

First-Line Management (No Antibiotics)

For immunocompetent patients with mild uncomplicated diverticulitis:

• Clear liquid diet during acute phase, advancing as symptoms improve 5, 2, 3
• Pain control with acetaminophen only 2, 4
• Observation without antibiotics 1, 2, 3
• Outpatient management when patients can tolerate oral intake, have no significant comorbidities, and have adequate home support 1, 2
• Mandatory re-evaluation within 7 days; earlier if clinical deterioration occurs 1, 2, 3

This approach is supported by high-quality evidence showing that antibiotics neither accelerate recovery nor prevent complications or recurrence in uncomplicated cases. 1, 2 Hospital stays are actually shorter in observation groups (2 vs 3 days). 1, 2

When Antibiotics ARE Indicated

Reserve antibiotics for patients with ANY of these high-risk features:

• Immunocompromised status (chemotherapy, organ transplant, high-dose steroids) 5, 1, 2, 3, 4
• Age >80 years 1, 2, 4
• Pregnancy 1, 4
• Significant comorbidities (cirrhosis, chronic kidney disease, heart failure, poorly controlled diabetes) 1, 2, 4
• Persistent fever or chills 1, 4
• Increasing leukocytosis or WBC >15 × 10^9/L 5, 1, 2
• CRP >140 mg/L 1, 2, 3
• Vomiting or inability to maintain hydration 5, 1, 2
• Fluid collection or longer segment of inflammation on CT 5, 1, 2, 3
• Symptoms >5 days 1, 2
• ASA score III or IV 1, 2

Antibiotic Regimens When Indicated

Outpatient oral regimens (4-7 days for immunocompetent patients):

• First-line: Amoxicillin-clavulanate 875/125 mg orally twice daily 1, 2, 4
• Alternative: Ciprofloxacin 500 mg orally twice daily PLUS Metronidazole 500 mg orally three times daily 5, 1, 2, 4

Inpatient IV regimens (transition to oral as soon as tolerated):

• Ceftriaxone PLUS Metronidazole 1, 2, 4
• Piperacillin-tazobactam 1, 2, 4
• Cefuroxime PLUS Metronidazole 1, 4

Duration of therapy:

• 4-7 days for immunocompetent patients 5, 1, 2, 3
• 10-14 days for immunocompromised patients 1, 2
• Transition from IV to oral as soon as patient tolerates oral intake to facilitate earlier discharge 1, 2, 3

Treatment of Complicated Diverticulitis

Small abscesses (<4-5 cm):

• Antibiotic therapy alone for 7 days 1, 3

Large abscesses (≥4-5 cm):

• Percutaneous drainage PLUS IV antibiotics for 4 days 5, 1, 3

Generalized peritonitis or sepsis:

• Emergent surgical consultation 3, 4
• IV antibiotics: Meropenem, Doripenem, Imipenem-cilastatin, or Piperacillin-tazobactam 1
• Surgical options: Primary resection with anastomosis or Hartmann's procedure 2

Inpatient vs Outpatient Decision

Hospitalization required for:

• Complicated diverticulitis 2, 3
• Inability to tolerate oral intake 1, 2, 3
• Severe pain or systemic symptoms 2, 3
• Significant comorbidities or frailty 1, 2
• Immunocompromised status 5, 1, 2

Outpatient management appropriate when:

• Uncomplicated diverticulitis 2, 3
• Can tolerate oral fluids and medications 1, 2
• No significant comorbidities 1, 2
• Adequate home support 1, 2
• Temperature <100.4°F and pain score <4/10 2

Outpatient management results in 35-83% cost savings per episode compared to hospitalization. 2

Prevention of Recurrence

Dietary and lifestyle modifications:

• High-quality diet rich in fiber from fruits, vegetables, whole grains, legumes; low in red meat and sweets 2
• Fiber intake >22.1 g/day shows protective effect 2
• Regular vigorous physical activity 2
• Achieve or maintain normal BMI 2
• Smoking cessation 2
• Avoid regular NSAID use when possible 2

Do NOT restrict nuts, corn, popcorn, or small-seeded fruits—these are NOT associated with increased diverticulitis risk. 5, 2

Critical Pitfalls to Avoid

• Overusing antibiotics in uncomplicated cases without risk factors contributes to resistance without clinical benefit 1, 2, 3
• Failing to recognize high-risk patients who need antibiotics despite having uncomplicated disease can lead to progression 1, 3
• Applying the "no antibiotics" approach to complicated diverticulitis (Hinchey 1b or higher)—these patients were specifically excluded from trials 2
• Assuming all patients require hospitalization when most can be safely managed outpatient with appropriate follow-up 2
• Stopping antibiotics early even if symptoms improve—complete the full course when indicated 2
• Unnecessarily restricting diet (nuts, seeds, popcorn) without evidence 2