What is the best approach to treat a patient with diverticulitis (inflammation of the diverticula in the colon)?

Treatment of Diverticulitis

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

Initial Risk Stratification

Before deciding on treatment, classify the patient based on CT imaging and clinical features:

• Uncomplicated diverticulitis is defined as localized inflammation without abscess, perforation, fistula, obstruction, or bleeding—confirmed by CT scan with 98-99% sensitivity and 99-100% specificity 1, 3
• Complicated diverticulitis involves any of these features: abscess ≥4 cm, perforation, fistula, obstruction, or generalized peritonitis 1, 2
• High-risk features predicting progression include: WBC >15 × 10⁹ cells/L, CRP >140 mg/L, symptoms >5 days, vomiting, pain score ≥8/10, ASA score III-IV, or CT findings of pericolic extraluminal air or fluid collection 1

Treatment Algorithm for Uncomplicated Diverticulitis

Observation Without Antibiotics (First-Line for Most Patients)

Multiple high-quality randomized trials, including the DIABOLO trial with 528 patients, demonstrate that antibiotics neither accelerate recovery nor prevent complications or recurrence in immunocompetent patients with uncomplicated diverticulitis. 1, 2

• Clear liquid diet during acute phase, advancing as symptoms improve 1
• Pain control with acetaminophen only 1, 3
• Hospital stay is actually shorter in observation groups (2 vs 3 days) compared to antibiotic-treated patients 1
• Re-evaluation within 7 days is mandatory, or sooner if clinical deterioration occurs 1, 2

When to Prescribe Antibiotics for Uncomplicated Diverticulitis

Reserve antibiotics ONLY for patients with these specific high-risk features: 1, 3

• Immunocompromised status: chemotherapy, high-dose steroids (>20 mg prednisone daily), organ transplant recipients 1
• Age >80 years 1, 3
• Pregnancy 1, 3
• Persistent fever or chills despite 48 hours of supportive care 1, 3
• Increasing leukocytosis (WBC >15 × 10⁹ cells/L) 1
• Elevated inflammatory markers: CRP >140 mg/L 1, 3
• Refractory symptoms or vomiting preventing oral hydration 1, 3
• Significant comorbidities: cirrhosis, chronic kidney disease, heart failure, poorly controlled diabetes 1, 3
• CT findings: fluid collection, longer segment of inflammation, or pericolic extraluminal air 1

Antibiotic Regimens When Indicated

Outpatient oral therapy (4-7 days for immunocompetent patients): 1, 4, 3

• First-line: Ciprofloxacin 500 mg twice daily PLUS metronidazole 500 mg three times daily 1, 4
• Alternative: Amoxicillin-clavulanate 875/125 mg twice daily 1, 4, 3

Inpatient IV therapy (transition to oral as soon as tolerated): 1, 4, 3

• Ceftriaxone PLUS metronidazole 1, 3
• Piperacillin-tazobactam 1, 3
• Cefuroxime PLUS metronidazole 4, 3

Duration of antibiotic therapy: 1, 4

• 4-7 days for immunocompetent patients 1, 4
• 10-14 days for immunocompromised patients 1, 4

Outpatient vs Inpatient Management

Outpatient management is appropriate when ALL criteria are met: 1, 2

• Tolerates oral fluids and medications 1, 2
• Temperature <100.4°F 1
• Pain score <4/10 controlled with acetaminophen 1
• No significant comorbidities or frailty 1, 2
• Adequate home and social support 1, 2
• No signs of sepsis or systemic inflammatory response 1

Hospitalization is required for: 1, 2

• Complicated diverticulitis 1, 2
• Inability to tolerate oral intake 1, 2
• Severe pain or systemic symptoms 1, 2
• Significant comorbidities or frailty 1, 2
• Immunocompromised status 1, 2
• Signs of sepsis or peritonitis 1

Treatment of Complicated Diverticulitis

Abscess Management

Small abscesses (<4-5 cm): 1, 2

• IV antibiotics alone for 7 days 1, 2
• Piperacillin-tazobactam OR ceftriaxone plus metronidazole 1, 3

Large abscesses (≥4-5 cm): 1, 2

• Percutaneous CT-guided drainage PLUS IV antibiotics 1, 2
• Continue antibiotics for 4 days after adequate drainage in immunocompetent patients 1, 4
• Cultures from drainage guide antibiotic selection 1

Generalized Peritonitis or Sepsis

Emergent surgical consultation is mandatory for: 1, 2, 3

• Generalized peritonitis 1, 2, 3
• Sepsis or septic shock 1, 3
• Failed medical management after 5-7 days 1
• Failed percutaneous drainage 1

Surgical options include: 1, 3

• Primary resection with anastomosis (preferred in stable patients) 1
• Hartmann's procedure (reserved for critically ill patients with diffuse peritonitis) 1, 3
• Postoperative mortality: 0.5% for elective resection vs 10.6% for emergent resection 3

Special Populations

Immunocompromised Patients

These patients require a lower threshold for CT imaging, antibiotic treatment, and surgical consultation: 1

• May present with milder signs despite more severe disease 1
• Corticosteroid use specifically increases risk of perforation and death 1
• Require longer antibiotic duration: 10-14 days 1, 4

Elderly Patients (>65 years)

• Require antibiotic therapy even for localized complicated diverticulitis 1, 4
• Surgery carries higher mortality and is reserved for failure of non-operative management 4
• Further diagnostic investigation is needed if symptoms persist beyond 5-7 days of antibiotic treatment 1

Prevention of Recurrence

After resolution of acute diverticulitis, implement these evidence-based lifestyle modifications: 1, 2, 5

• High-quality diet: high in fiber (>22.1 g/day) from fruits, vegetables, whole grains, legumes; low in red meat and sweets 1, 2, 5
• Regular vigorous physical activity 1, 2, 5
• Achieve or maintain BMI 18-25 kg/m² 1, 2, 5
• Smoking cessation 1, 2, 5
• Avoid regular use of NSAIDs and opioids when possible 1, 2, 5

Do NOT restrict consumption of nuts, corn, popcorn, or small-seeded fruits—these are not associated with increased risk of diverticulitis. 1, 5

Follow-Up Care

Colonoscopy Recommendations

Colonoscopy should be performed 4-6 weeks after symptom resolution for: 1, 5

• Complicated diverticulitis (7.9% risk of colon cancer) 1
• First episode of uncomplicated diverticulitis in patients >50 years requiring routine screening 1
• Patients who have not had high-quality colonoscopy in the past year 1, 5

Colonoscopy is NOT routinely needed for uncomplicated diverticulitis confirmed by CT in patients with recent screening (1.16% risk of colorectal cancer). 1

Surgical Considerations for Recurrent Diverticulitis

The traditional "two-episode rule" for elective surgery is no longer accepted. 1

Elective sigmoidectomy should be considered when: 1

• ≥3 episodes of CT-confirmed diverticulitis within 2 years 1
• Persistent symptoms >3 months (smoldering diverticulitis) 1
• History of complicated diverticulitis 1
• Significant quality of life impairment 1
• Immunocompromised status 1

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

Critical Pitfalls to Avoid

• Do NOT routinely prescribe antibiotics for uncomplicated diverticulitis in immunocompetent patients without risk factors—this provides no benefit and contributes to antibiotic resistance 1, 2
• Do NOT apply the "no antibiotics" approach to Hinchey 1b/2 or higher disease—the evidence specifically excluded these patients 1
• Do NOT extend antibiotics beyond 7 days in immunocompetent patients with adequate source control—this does not improve outcomes 1
• Do NOT stop antibiotics early if they are indicated, even if symptoms improve 1
• Do NOT prescribe mesalamine or rifaximin for prevention of recurrent diverticulitis—high-certainty evidence shows no benefit 1
• Do NOT delay surgical consultation in patients with frequent recurrences affecting quality of life 1
• Do NOT use first-generation cephalosporins (like cefazolin) for diverticulitis—they lack adequate gram-negative coverage 4