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 alone. 1, 2

Defining Uncomplicated vs. Complicated Disease

Uncomplicated diverticulitis is localized inflammation without abscess, perforation, fistula, obstruction, or bleeding, confirmed by CT scan showing diverticula, wall thickening, and increased pericolic fat density. 1, 2 Approximately 85% of acute diverticulitis cases are uncomplicated. 3

Complicated diverticulitis involves abscess formation, perforation with free air, fistula, obstruction, or generalized peritonitis. 1, 3

Diagnostic Approach

CT scan with IV contrast is the gold standard for diagnosing diverticulitis, with 98-99% sensitivity and 99-100% specificity. 4, 1, 3 In elderly patients or those with suspected diverticulitis who cannot undergo CT with IV contrast (severe kidney disease or contrast allergy), use ultrasound, MRI, or CT without contrast as alternatives. 4

Laboratory workup should include complete blood count, C-reactive protein, and basic metabolic panel. 1, 5

Treatment Algorithm for Uncomplicated Diverticulitis

First-Line Management (No Antibiotics)

Most immunocompetent patients with uncomplicated diverticulitis do NOT require antibiotics, as multiple high-quality randomized trials including the DIABOLO trial with 528 patients demonstrated that antibiotics neither accelerate recovery nor prevent complications or recurrence. 1, 2

Outpatient management consists of:

• Clear liquid diet during acute phase, advancing as symptoms improve 1, 2
• Pain control with acetaminophen only (avoid NSAIDs as they increase diverticulitis risk) 1, 2
• Re-evaluation within 7 days, or sooner if clinical deterioration occurs 1, 2

Outpatient treatment is appropriate when patients meet ALL criteria:

• Temperature <100.4°F (38°C) 1, 2
• Pain score <4/10 controlled with acetaminophen alone 1, 2
• Able to tolerate oral fluids and medications 1, 2
• No significant comorbidities (cirrhosis, chronic kidney disease, heart failure, poorly controlled diabetes) 1
• Adequate home and social support 1, 2

Hospital stays are actually shorter in observation groups (2 vs 3 days) compared to antibiotic-treated patients. 1, 2

When Antibiotics ARE Indicated

Reserve antibiotics for patients with specific high-risk features: 1, 2

Absolute indications:

• Immunocompromised status: chemotherapy, high-dose steroids (>20mg prednisone daily), organ transplant recipients 1, 3
• Age >80 years 1, 3
• Pregnancy 1, 3
• Systemic inflammatory response or sepsis: persistent fever >101°F, chills despite supportive care 1, 3

Clinical indicators:

• Increasing leukocytosis (WBC >15 × 10⁹ cells/L) 1
• Elevated inflammatory markers (CRP >140 mg/L) 1
• Refractory symptoms or vomiting preventing oral hydration 1
• Symptoms lasting >5 days prior to presentation 1
• ASA score III or IV 1
• Significant comorbidities or frailty 1

CT imaging indicators:

• Fluid collection or abscess on CT 1
• Longer segment of inflammation (>5cm) 1
• Pericolic extraluminal air 1

Antibiotic Regimens When Indicated

Outpatient oral regimens (4-7 days): 1, 3

• First-line: Ciprofloxacin 500 mg orally twice daily PLUS metronidazole 500 mg orally three times daily 1, 3
• Alternative: Amoxicillin-clavulanate 875/125 mg orally twice daily 1, 3

Inpatient IV regimens: 1, 3

• Ceftriaxone PLUS metronidazole 1, 3
• Piperacillin-tazobactam 1, 3
• Cefuroxime PLUS metronidazole 6, 3
• Transition to oral antibiotics as soon as patient tolerates oral intake to facilitate earlier discharge 1, 2

Duration of therapy:

• Immunocompetent patients: 4-7 days 1, 6
• Immunocompromised patients: 10-14 days 1, 6
• Post-drainage of abscess with adequate source control: 4 days 1, 6

Treatment of Complicated Diverticulitis

Abscess Management

Small abscesses (<4-5 cm): IV antibiotics alone for 7 days may be sufficient. 4, 1

Large abscesses (≥4-5 cm): Percutaneous CT-guided drainage PLUS IV antibiotics for 4 days after adequate source control. 4, 1 Cultures from drainage should guide antibiotic selection. 4, 1

Peritonitis and Surgical Indications

Distant free air without diffuse fluid: Non-operative management may be attempted in highly selected, hemodynamically stable patients with close monitoring, but has a high failure rate (57-60%) and surgical consultation is warranted. 4

Diffuse peritonitis or sepsis: Emergent surgical consultation and source control surgery (Hartmann's procedure or primary resection with anastomosis) is mandatory. 4, 1 Non-operative management is NOT recommended. 4

Antibiotic regimens for complicated disease:

• Standard: Ceftriaxone PLUS metronidazole or Piperacillin-tazobactam 1, 3
• Critically ill/immunocompromised: Meropenem, Doripenem, Imipenem-cilastatin, or Eravacycline 6

Special Population Considerations

Elderly Patients (>65 years)

Elderly patients require antibiotic therapy even for localized complicated diverticulitis (WSES stage 1a-1b) with moderate quality evidence. 4 They have higher risk of complications and mortality, requiring lower threshold for hospitalization and surgical consultation. 4

Immunocompromised Patients

Require 10-14 days of antibiotic therapy, lower threshold for CT imaging, and earlier surgical consultation. 1 Corticosteroid use specifically increases risk of perforation and death. 1

Post-Acute Management

Colonoscopy Timing

Perform colonoscopy 4-6 weeks after symptom resolution for patients with complicated diverticulitis, first episode in patients >50 years, or those without high-quality colonoscopy in past year to exclude malignancy (1.16% risk of colorectal cancer in uncomplicated cases, 7.9% in complicated cases). 1, 5

Prevention of Recurrence

Dietary modifications: 1, 5

• High-quality diet: high in fiber from fruits, vegetables, whole grains, legumes (>22.1 g/day); low in red meat and sweets 1
• Do NOT restrict nuts, corn, popcorn, or small-seeded fruits (no evidence of increased risk) 1

Lifestyle modifications: 1, 5

• Regular vigorous physical activity 1
• Achieve or maintain BMI 18-25 kg/m² 1
• Smoking cessation 1
• Avoid nonaspirin NSAIDs when possible (aspirin is acceptable) 1
• Avoid opioids when possible 1

Do NOT prescribe mesalamine or rifaximin for prevention - strong evidence shows no benefit but increased adverse events. 1

Elective Surgery Considerations

Elective sigmoid resection should NOT be based on number of episodes alone. 4, 1 The traditional "two-episode rule" is no longer accepted. 1

Consider elective resection for: 4, 1

• ≥3 episodes within 2 years with significant quality of life impact 1
• Persistent symptoms >3 months (smoldering diverticulitis) 1
• Complicated diverticulitis with stenosis, fistula, or recurrent bleeding 4
• Immunocompromised patients (if fit for surgery) 4

The DIRECT trial demonstrated significantly better quality of life at 6 months and 5-year follow-up after elective sigmoidectomy compared with continued conservative management. 1

Critical Pitfalls to Avoid

• Overusing antibiotics in uncomplicated cases without risk factors provides no benefit and contributes to antibiotic resistance 1, 2
• Failing to recognize high-risk patients who need antibiotics despite having uncomplicated disease can lead to progression 1
• Assuming all patients require hospitalization when most can be safely managed outpatient with 35-83% cost savings 4, 1
• Unnecessarily restricting diet (avoiding nuts, seeds, popcorn) is not evidence-based and may reduce overall fiber intake 1
• Stopping antibiotics early even if symptoms improve when antibiotics are indicated 1
• Applying the "no antibiotics" approach to complicated diverticulitis (Hinchey 1b or higher) as evidence specifically excluded these patients 1
• Delaying surgical consultation in patients with frequent recurrence affecting quality of life 1