For a patient presenting with left lower quadrant pain, fever, leukocytosis and no peritoneal signs, how should uncomplicated diverticulitis be evaluated and managed on an outpatient basis?

Outpatient Management of Uncomplicated Diverticulitis

For an immunocompetent patient presenting with left lower quadrant pain, fever, and leukocytosis but no peritoneal signs, obtain a CT abdomen/pelvis with IV contrast to confirm uncomplicated diverticulitis, then manage outpatient with observation and supportive care alone—antibiotics are NOT routinely indicated unless specific high-risk features are present. 1

Diagnostic Confirmation

CT imaging is mandatory before making treatment decisions. Clinical examination alone misdiagnoses diverticulitis in 34–68% of cases, and the classic triad of left lower quadrant pain, fever, and leukocytosis occurs in only 25% of patients. 1, 2

• Order CT abdomen/pelvis with IV contrast immediately (98–99% sensitivity and specificity). 1, 3
• CT confirms uncomplicated disease (no abscess, perforation, fistula, obstruction) and excludes alternative diagnoses like colon cancer. 1, 2
• Obtain complete blood count, C-reactive protein, and basic metabolic panel. 4

Outpatient Eligibility Criteria

The patient can be managed outpatient if ALL of the following are met: 1

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

Outpatient management saves 35–83% in costs compared to hospitalization and has only a 4.3% failure rate requiring subsequent admission. 1

First-Line Treatment: Observation Without Antibiotics

For immunocompetent patients with uncomplicated diverticulitis, observation with supportive care is the standard approach—antibiotics do NOT accelerate recovery, prevent complications, or reduce recurrence. 1, 3 This recommendation is based on high-quality evidence from the DIABOLO trial (528 patients) showing no benefit of antibiotics. 1

Supportive Care Protocol:

• Clear liquid diet for 2–3 days, then advance as tolerated 1, 4
• Acetaminophen for pain (avoid NSAIDs) 1
• Adequate oral hydration 1
• Bowel rest during acute phase 1

Selective Antibiotic Use: High-Risk Features

Reserve antibiotics ONLY for patients with any of the following: 1, 3

Clinical Indicators:

• Persistent fever >100.4°F or chills despite supportive care 1
• Refractory symptoms or vomiting 1
• Inability to maintain oral hydration 1
• Symptom duration >5 days before presentation 1

Laboratory Indicators:

• C-reactive protein >140 mg/L 1
• White blood cell count >15 × 10⁹/L or rising leukocytosis 1, 3

CT Findings:

• Fluid collection or abscess 1
• Extensive segment of inflammation 1
• Pericolic extraluminal air 1

Patient Factors:

• Immunocompromised status (chemotherapy, high-dose steroids, organ transplant) 1, 3
• Age >80 years 1, 3
• Pregnancy 1, 3
• ASA physical status III–IV 1
• Significant comorbidities or frailty 1

Antibiotic Regimens When Indicated

If antibiotics are necessary, use oral regimens for 4–7 days: 1, 3

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

Duration: 4–7 days for immunocompetent patients; 10–14 days for immunocompromised patients. 1

Follow-Up Protocol

Mandatory re-evaluation within 7 days of diagnosis (or sooner if symptoms worsen). 1, 2

Return immediately if:

• Fever develops or worsens 1
• Severe or progressively worsening pain 1
• Inability to tolerate oral intake 1
• Signs of peritonitis (guarding, rebound tenderness) 1
• Persistent symptoms beyond 2–3 days despite conservative management 2

If symptoms persist after 5–7 days, obtain repeat CT to assess for complications. 1

Post-Acute Colonoscopy

Schedule colonoscopy 6–8 weeks after symptom resolution for: 1

• First episode of uncomplicated diverticulitis (if no recent high-quality colonoscopy) 1
• Any complicated episode (7.9% associated cancer risk) 1
• Patients >50 years needing routine screening 1
• Presence of alarm features (change in stool caliber, iron-deficiency anemia, rectal bleeding, weight loss) 1

Recurrence Prevention

Counsel patients on lifestyle modifications: 1

• High-fiber diet (≥22 g/day from fruits, vegetables, whole grains, legumes) combined with low intake of red meat and sweets 1
• Regular vigorous physical activity 1
• Maintain normal BMI (18–25 kg/m²) 1
• Smoking cessation 1
• Avoid nonaspirin NSAIDs when possible 1

Do NOT restrict nuts, corn, popcorn, or small-seeded fruits—they are not linked to increased diverticulitis risk. 1

Critical Pitfalls to Avoid

• Do NOT prescribe routine antibiotics for uncomplicated diverticulitis lacking high-risk features—this contributes to antimicrobial resistance without clinical benefit. 1
• Do NOT withhold antibiotics without first confirming uncomplicated disease on CT imaging. 1
• Do NOT overlook immunocompromised patients—they need immediate antibiotics (10–14 days) and a lower threshold for repeat imaging and surgical consultation. 1
• Do NOT assume all patients require hospitalization—most can be safely managed outpatient with proper follow-up. 1