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. 1, 3 This imaging confirms the diagnosis and distinguishes uncomplicated from complicated disease. 4

For elderly patients 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

Treatment Algorithm for Uncomplicated Diverticulitis

First-Line Management (No Antibiotics)

Most immunocompetent patients do NOT require antibiotics. 1, 2 The DIABOLO trial with 528 patients demonstrated that antibiotics neither accelerate recovery nor prevent complications or recurrence in uncomplicated cases. 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) 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) 2
• Pain score <4/10 controlled with acetaminophen alone 2
• Able to tolerate oral fluids and medications 1, 2
• No significant comorbidities (cirrhosis, chronic kidney disease, heart failure, poorly controlled diabetes) 2
• 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, 2, 3
• Age >80 years 1, 2, 3
• Pregnancy 1, 2, 3
• Systemic inflammatory response or sepsis (persistent fever >101°F, chills despite supportive care) 1, 2, 3

Clinical indicators:

• Increasing leukocytosis (WBC >15 × 10⁹ cells/L) 1, 2
• Elevated inflammatory markers (CRP >140 mg/L) 1, 2
• Refractory symptoms or vomiting preventing oral hydration 1, 2
• Symptoms lasting >5 days prior to presentation 1, 2
• ASA score III or IV 1, 2

CT imaging indicators:

• Fluid collection or abscess on CT 1, 2
• Longer segment of inflammation (>5cm) 1, 2
• Pericolic extraluminal air 1, 2

Antibiotic Regimens When Indicated

Outpatient oral regimens (4-7 days):

• First-line: Ciprofloxacin 500 mg orally twice daily PLUS metronidazole 500 mg orally three times daily 1, 2, 3
• Alternative: Amoxicillin-clavulanate 875/125 mg orally twice daily 1, 2, 3

Inpatient IV regimens:

• Ceftriaxone PLUS metronidazole 1, 2, 3
• Piperacillin-tazobactam 1, 2, 3
• Cefuroxime PLUS metronidazole 5, 3

Transition to oral antibiotics as soon as the patient tolerates oral intake to facilitate earlier discharge. 1, 2

Duration of therapy:

• Immunocompetent patients: 4-7 days 1, 2, 5
• Immunocompromised patients: 10-14 days 1, 2
• Post-drainage of abscess with adequate source control: 4 days 1, 2

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 therapy. 4

Peritonitis and Perforation

Patients with CT findings of distant free gas without diffuse intra-abdominal fluid: Non-operative management may be attempted in highly selected, hemodynamically stable patients with close monitoring, but this carries a significant failure rate (57-60%). 4 In elderly patients, non-operative management is NOT recommended as a viable option. 4

Patients with diffuse peritonitis (WSES stage 3-4): Prompt and effective source control surgery is mandatory. 4 Surgical options include:

• Primary resection with anastomosis (with or without diverting stoma) in stable patients without comorbidities 4
• Hartmann's procedure in unstable patients or those with multiple comorbidities 4

Laparoscopic peritoneal lavage should NOT be considered first-line treatment for patients with generalized peritonitis. 4

Post-Acute Management

Colonoscopy Timing

Perform colonoscopy 4-6 weeks after symptom resolution for patients with:

• Complicated diverticulitis (7.9% risk of colon cancer) 1
• First episode of uncomplicated diverticulitis in patients >50 years requiring routine screening 4, 1
• Patients who haven't had high-quality colonoscopy in the past year 1

The risk of colorectal cancer after uncomplicated diverticulitis is 1.16%, making routine colonoscopy unnecessary unless other indications exist. 4, 1

Prevention of Recurrence

Dietary modifications:

• High-quality diet rich in fiber from fruits, vegetables, whole grains, and legumes (>22.1 g/day) 1, 2
• Low in red meat and sweets 1, 2
• Do NOT restrict nuts, corn, popcorn, or small-seeded fruits (no evidence of increased risk) 1, 2

Lifestyle modifications:

• Regular vigorous physical activity 1, 2
• Achieve or maintain normal BMI (18-25 kg/m²) 1, 2
• Smoking cessation 1, 2
• Avoid nonaspirin NSAIDs when possible (aspirin is acceptable) 1, 2

Do NOT prescribe mesalamine or rifaximin for prevention of recurrent diverticulitis—high-certainty 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:

• High-risk patients (immunocompromised, if fit for surgery) after conservatively treated episode 4
• Stenosis, fistulae, or recurrent diverticular bleeding 4
• Very symptomatic disease compromising quality of life 4
• ≥3 episodes within 2 years with persistent symptoms >3 months 1

The DIRECT trial demonstrated that elective sigmoidectomy results in significantly better quality of life at 6 months compared to continued conservative management in patients with recurrent/persistent symptoms. 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, 2
• 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, 2
• Stopping antibiotics early even if symptoms improve—when antibiotics are indicated, complete the full course. 1
• Applying the "no antibiotics" approach to complicated diverticulitis (Hinchey 1b or higher)—the evidence specifically excluded these patients. 1
• Delaying surgical consultation in patients with frequent recurrence affecting quality of life. 1