What is the treatment approach for a middle-aged or older adult with a history of diverticulosis presenting with diverticulitis symptoms, including abdominal pain, tenderness, and changes in bowel habits?

Treatment Approach for Diverticulitis

For a middle-aged or older adult presenting with suspected diverticulitis, obtain a CT scan with IV contrast to confirm the diagnosis and guide treatment, then manage most immunocompetent patients with uncomplicated disease using observation and supportive care alone—reserving antibiotics only for those with specific high-risk features. 1, 2, 3

Initial Diagnostic Confirmation

CT imaging is essential for patients without prior imaging-confirmed diverticulitis, those with severe presentations, immunocompromised status, or multiple recurrences. 1, 3 CT scan with oral and IV contrast has 98-99% sensitivity and 99-100% specificity for diagnosing diverticulitis. 3, 4

Key Clinical Presentation Features to Assess:

• Left lower quadrant abdominal pain (most common symptom) 1, 3
• Fever and abdominal tenderness on examination 1, 3
• Change in bowel habits, nausea, elevated WBC count and C-reactive protein 1, 3

Classification: Uncomplicated vs. Complicated Disease

Uncomplicated Diverticulitis (85-88% of cases):

• Localized colon wall thickening and peri-colonic inflammation without abscess, perforation, fistula, obstruction, or bleeding 3, 4, 5

Complicated Diverticulitis (12-15% of cases):

• Presence of abscess, phlegmon, peritonitis, fistula, obstruction, or perforation 3, 4

Treatment Algorithm for Uncomplicated Diverticulitis

Step 1: Determine if Antibiotics Are Needed

Most immunocompetent patients with uncomplicated diverticulitis do NOT require antibiotics. 1, 2, 4 Multiple high-quality randomized trials, including the DIABOLO trial with 528 patients, demonstrate that antibiotics neither accelerate recovery nor prevent complications or recurrence in uncomplicated cases. 2

Step 2: Identify High-Risk Features Requiring Antibiotics

Reserve antibiotics for patients with ANY of these criteria: 1, 2, 4

• Immunocompromised status (chemotherapy, high-dose steroids, organ transplant) 1, 2, 4
• Age >80 years 1, 2
• Pregnancy 1, 2
• Persistent fever or chills despite supportive care 2, 4
• Increasing leukocytosis 2, 4
• CRP >140 mg/L 1, 2
• WBC >15 × 10⁹ cells/L 1, 2
• Vomiting or inability to maintain oral hydration 1, 2
• Symptoms lasting >5 days prior to presentation 1, 2
• CT findings of fluid collection, pericolic extraluminal air, or longer inflamed colon segment 1, 2
• Significant comorbidities (cirrhosis, chronic kidney disease, heart failure, poorly controlled diabetes) 2, 4
• ASA score III or IV 1, 2

Step 3: Outpatient vs. Inpatient Management

Outpatient management is appropriate when patients meet ALL criteria: 1, 2

• Can tolerate oral fluids and medications 1, 2
• Temperature <100.4°F 2
• Pain controlled with acetaminophen alone (pain score <4/10) 2
• No significant comorbidities or frailty 1, 2
• Adequate home and social support 1, 2
• No signs of sepsis or peritonitis 2

Hospitalization is required for: 2, 3

• Complicated diverticulitis 2, 3
• Inability to tolerate oral intake 2
• Severe pain or systemic symptoms 2
• Signs of peritonitis or sepsis 2
• Immunocompromised status with concerning features 1, 2

Specific Antibiotic Regimens (When Indicated)

Outpatient Oral Therapy (4-7 days for immunocompetent patients):

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

Inpatient IV Therapy:

• Ceftriaxone PLUS metronidazole 2, 3, 4
• Piperacillin-tazobactam 2, 3, 4
• Transition to oral antibiotics as soon as patient tolerates oral intake to facilitate earlier discharge 1, 2

Duration of Antibiotic Therapy:

• 4-7 days for immunocompetent patients with uncomplicated disease 1, 2
• 10-14 days for immunocompromised patients 1, 2

Supportive Care for All Patients

• Clear liquid diet during acute phase, advancing as tolerated 2, 3
• Pain management with acetaminophen (avoid NSAIDs and opioids when possible) 2, 3, 4
• Adequate hydration 2

Treatment of Complicated Diverticulitis

For Abscesses:

• Small abscesses (<4-5 cm): IV antibiotics alone may be sufficient 1, 2
• Large abscesses (≥4-5 cm): Percutaneous CT-guided drainage PLUS IV antibiotics 1, 2, 3
• Continue antibiotics for 4 days after adequate source control in immunocompetent patients 2

For Generalized Peritonitis or Sepsis:

• Emergent surgical consultation for source control surgery 1, 2, 3
• IV antibiotics immediately (ceftriaxone plus metronidazole or piperacillin-tazobactam) 2, 3
• Surgical options: Hartmann's procedure or primary resection with anastomosis 2

Mandatory Follow-Up and Monitoring

• Re-evaluation within 7 days from diagnosis, or earlier if symptoms worsen 1, 2
• Colonoscopy 6-8 weeks after symptom resolution for patients with complicated diverticulitis, first episode of uncomplicated diverticulitis, or those >50 years requiring routine screening 1, 2, 3
• Earlier colonoscopy indicated for patients with alarm symptoms (unintentional weight loss, bloody stools, persistent pain) 1

Prevention of Recurrence

Lifestyle Modifications:

• High-quality diet rich in fiber (>22.1 g/day) from fruits, vegetables, whole grains, and legumes; low in red meat and sweets 1, 2, 3
• Regular vigorous physical activity 1, 2
• Achieve or maintain normal BMI (18-25 kg/m²) 1, 2
• Smoking cessation 1, 2
• Avoid chronic NSAID use (except aspirin for cardiovascular prevention) 1, 2

What NOT to Do:

• Do NOT restrict nuts, corn, popcorn, or small-seeded fruits—these are not associated with increased diverticulitis risk 1, 2
• Do NOT prescribe mesalamine or rifaximin for prevention—high-certainty evidence shows no benefit 1, 2

Surgical Considerations for Recurrent Disease

Elective sigmoidectomy should NOT be based on number of episodes alone. 1 The decision should be individualized based on: 1

• Quality of life impact (significant impairment of daily activities) 1
• Frequency of recurrence (≥3 episodes within 2 years) 1, 2
• Persistent symptoms >3 months (smoldering diverticulitis) 1
• History of complicated diverticulitis 1
• Patient preferences and surgical risk 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 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—this contributes to antibiotic resistance without clinical benefit 1, 2
• Do NOT assume all patients require hospitalization—outpatient management results in 35-83% cost savings and reduced hospital-acquired infections 1, 2
• Do NOT perform colonoscopy during acute phase—wait minimum 6-8 weeks after complete symptom resolution 1, 2
• Do NOT apply the "no antibiotics" approach to complicated diverticulitis or immunocompromised patients—these populations always require antibiotics 2
• Do NOT extend antibiotics beyond 7 days in immunocompetent patients with adequate response—this does not improve outcomes 2
• Do NOT delay surgical consultation in patients with frequent recurrences significantly affecting quality of life 2