What is the recommended treatment for diverticulitis?

Treatment of Diverticulitis

For immunocompetent patients with uncomplicated diverticulitis without systemic inflammation, antibiotics are not recommended—observation with bowel rest and pain control is the first-line approach. 1, 2

Classification and Diagnostic Confirmation

Uncomplicated diverticulitis is defined as localized diverticular inflammation without abscess, perforation, fistula, obstruction, or bleeding. 1 Complicated diverticulitis involves inflammation with abscess, phlegmon, fistula, obstruction, bleeding, or perforation. 3, 4

• CT scan with IV contrast is the gold standard diagnostic test with 98-99% sensitivity and 99-100% specificity. 3, 5
• CT findings in uncomplicated disease include diverticula, bowel wall thickening, and increased pericolic fat density. 1
• CT findings suggesting complicated disease include extraluminal gas, intra-abdominal fluid, or abscess formation. 6, 5

Treatment Algorithm for Uncomplicated Diverticulitis

Step 1: Determine if Antibiotics Are Needed

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

Reserve antibiotics for patients with ANY of these high-risk features: 2, 3

• Immunocompromised status (chemotherapy, organ transplant, chronic corticosteroids)
• Age >80 years
• Pregnancy
• Persistent fever or chills
• Increasing leukocytosis or WBC >15 × 10⁹ cells/L
• CRP >140 mg/L
• Systemic inflammatory response or sepsis
• Vomiting or inability to maintain hydration
• Symptoms >5 days duration
• ASA score III or IV
• CT findings of pericolic extraluminal gas, fluid collection, or longer inflamed segment

Step 2: Determine Inpatient vs. Outpatient Management

Outpatient management is appropriate when ALL criteria are met: 7, 2

• Able to tolerate oral fluids and medications
• Temperature <100.4°F (38°C)
• Pain score <4/10 (controlled with acetaminophen)
• No significant comorbidities or frailty
• Adequate home support and ability to maintain self-care
• No signs of sepsis or peritonitis

Hospitalization is required for: 7, 2, 5

• Complicated diverticulitis
• Inability to tolerate oral intake
• Severe pain or systemic symptoms
• Significant comorbidities or frailty
• Immunocompromised status
• Signs of peritonitis or sepsis

Step 3: Conservative Management (No Antibiotics)

For patients WITHOUT high-risk features: 2, 3

• Clear liquid diet during acute phase, advancing as tolerated
• Pain control with acetaminophen (avoid NSAIDs and opioids)
• Bowel rest
• Mandatory re-evaluation within 7 days, or sooner if clinical deterioration 7, 2

Step 4: Antibiotic Regimens (When Indicated)

Outpatient oral regimens (4-7 days for immunocompetent patients): 2, 3

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

Inpatient IV regimens: 2, 3

• Ceftriaxone PLUS Metronidazole
• Piperacillin-tazobactam 4g/0.5g every 6 hours
• Ampicillin-sulbactam
• Transition to oral antibiotics as soon as patient tolerates oral intake to facilitate earlier discharge 1

Duration of antibiotic therapy: 2, 6

• Immunocompetent patients: 4-7 days
• Immunocompromised patients: 10-14 days
• Post-drainage with adequate source control: 4 days

Treatment of Complicated Diverticulitis

Small Abscesses (<4-5 cm)

• Initial trial of IV antibiotics alone is appropriate. 7, 6
• Pooled failure rate is 20% with mortality rate of 0.6%. 7
• Close clinical monitoring for signs of treatment failure. 6

Large Abscesses (≥4-5 cm)

• Percutaneous drainage PLUS IV antibiotics is the recommended approach. 7, 6
• If percutaneous drainage is not feasible in non-critically ill, immunocompetent patients, antibiotics alone can be attempted with close monitoring. 6
• In critically ill or immunocompromised patients where drainage is not feasible, surgical intervention should be considered. 6

Microperforation with Pericolic Gas

• For hemodynamically stable patients with small amounts of pericolic extraluminal gas without diffuse peritonitis, non-operative treatment with antibiotics is appropriate. 6
• Patients with distant free gas without diffuse intra-abdominal fluid may be treated non-operatively only with close follow-up, though failure rate is 57-60%. 6

Diffuse Peritonitis or Sepsis

Immediate management includes: 7, 6, 5

• Prompt fluid resuscitation
• Immediate IV antibiotic administration (ceftriaxone plus metronidazole or piperacillin-tazobactam)
• Urgent surgical consultation for emergent laparotomy with colonic resection

Surgical options include: 6, 5

• Primary resection with anastomosis (with or without diverting stoma) for stable patients
• Hartmann procedure for critically ill patients with diffuse peritonitis
• Postoperative mortality: 0.5% for elective resection vs. 10.6% for emergent resection 3

Special Populations

Immunocompromised Patients

These patients are at high risk for failure of standard non-operative treatment. 1 They require: 1, 2

• Lower threshold for CT imaging, antibiotic treatment, and surgical consultation
• Emergency surgery rate is 39.3%, with postoperative mortality of 31.6%
• Patients on chronic corticosteroid therapy have the highest risk
• Antibiotic duration of 10-14 days (vs. 4-7 days for immunocompetent patients)

Patients with Pericolic Extraluminal Gas

• A trial of non-operative treatment with antibiotics is recommended. 7
• Elevated CRP levels may predict treatment failure. 7
• Close monitoring is essential as these patients are at higher risk for progression.

Prevention of Recurrence

Lifestyle modifications to reduce recurrence risk: 2

• High-quality diet: high in fiber from fruits, vegetables, whole grains, legumes; low in red meat and sweets
• Achieve or maintain normal body mass index
• Regular physical activity, particularly vigorous exercise
• Smoking cessation
• Avoid regular use of NSAIDs and opioids when possible

Dietary myths to dispel: 2

• Consumption of nuts, corn, popcorn, and small-seeded fruits is NOT associated with increased risk of diverticulitis
• Fiber supplements can be beneficial but are not a replacement for a high-quality diet

Elective Surgical Considerations

The traditional "two-episode rule" for elective surgery is no longer accepted. 7, 2 The decision for elective resection should be based on: 7

• Impact on quality of life
• Frequency of recurrence
• Risk of complicated disease
• Patient's comorbidities and ongoing symptoms
• Complexity of disease

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. 2

Critical Pitfalls to Avoid

• Do NOT routinely prescribe antibiotics for uncomplicated diverticulitis in immunocompetent patients without risk factors. 1, 2 This represents overuse without clinical benefit and contributes to antibiotic resistance.

• Do NOT apply the "no antibiotics" approach to patients with Hinchey 1b/2 or higher disease, as the evidence specifically excluded these patients. 2

• Do NOT assume all patients require hospitalization—most can be safely managed as outpatients with appropriate follow-up, resulting in cost savings of 35-83% per episode. 2

• Do NOT unnecessarily restrict nuts, seeds, and popcorn—these dietary restrictions are not evidence-based. 2

• Do NOT stop antibiotics early if they are indicated, even if symptoms improve—complete the full course. 2

• Do NOT delay surgical consultation in patients with frequent recurrences affecting quality of life. 2

• Do NOT withhold antibiotics from patients with sepsis due to diverticulitis, even in the context of leaving against medical advice—sepsis is an absolute indication for antibiotics. 2

• Do NOT fail to recognize high-risk features that predict progression to complicated disease, including age <50 years, pain score ≥8/10 at presentation, symptoms >5 days, vomiting, elevated inflammatory markers, or CT findings of fluid collections. 2, 6