What is the appropriate work‑up and management for a hemodynamically stable adult presenting with left‑sided abdominal pain, fever, and tenderness suggestive of uncomplicated diverticulitis?

Work-Up and Management of Suspected Uncomplicated Diverticulitis

Diagnostic Confirmation

Obtain CT abdomen-pelvis with IV contrast to confirm the diagnosis and assess for complications—this is the gold standard with 98–99% sensitivity and specificity. 1, 2 Clinical assessment alone misclassifies 34–68% of cases, making imaging essential even when the classic triad (left lower quadrant pain, fever, leukocytosis) is present. 2

Laboratory work-up should include:

• Complete blood count to assess for leukocytosis (WBC >15 × 10⁹/L predicts higher risk) 2
• C-reactive protein (CRP >140 mg/L indicates increased risk of progression) 2
• Basic metabolic panel to assess renal function and hydration status 3

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Risk Stratification After CT Confirmation

Uncomplicated Disease (No Abscess, Perforation, Fistula, or Obstruction)

For immunocompetent patients with uncomplicated diverticulitis, observation with supportive care alone—without antibiotics—is the first-line approach. 2, 4 The DIABOLO trial (528 patients) demonstrated that antibiotics neither accelerate recovery nor prevent complications or recurrence in this population. 2, 4

Supportive care includes:

• Clear liquid diet for 2–3 days, advancing as tolerated 2
• Adequate oral hydration 2
• Acetaminophen 1 g three times daily for pain (avoid NSAIDs) 2

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When to Add Antibiotics (Selective Use)

Reserve antibiotics for patients with ANY of the following high-risk features:

Clinical Indicators:

• Persistent fever >100.4°F or chills despite supportive care 2
• Refractory symptoms or vomiting 2
• Inability to maintain oral hydration 2
• Symptom duration >5 days before presentation 2, 3

Laboratory Markers:

• CRP >140 mg/L 2
• WBC >15 × 10⁹/L or rising leukocytosis 2

CT Findings:

• Fluid collection or small abscess 2
• Extensive segment of colonic inflammation 2
• Pericolic extraluminal air 2

Patient Factors:

• Immunocompromised status (chemotherapy, high-dose steroids, organ transplant) 2, 5
• Age >80 years 2
• Pregnancy 2
• Significant comorbidities (cirrhosis, CKD, heart failure, poorly controlled diabetes) 2
• ASA physical status III–IV 2

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Antibiotic Regimens When Indicated

Outpatient Oral Therapy (4–7 days for immunocompetent):

• First-line: Amoxicillin-clavulanate 875/125 mg PO twice daily 2
• Alternative: Ciprofloxacin 500 mg PO twice daily + Metronidazole 500 mg PO three times daily 2

Inpatient IV Therapy (transition to oral within 48 hours):

• Ceftriaxone + Metronidazole 2
• Piperacillin-tazobactam 2
• Amoxicillin-clavulanate 1.2 g IV q6h 2

Duration:

• Immunocompetent: 4–7 days total 2
• Immunocompromised: 10–14 days total 2

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Outpatient vs. Inpatient Management

Outpatient Eligibility (ALL criteria must be met):

• CT-confirmed uncomplicated disease 2
• Ability to tolerate oral fluids and medications 2
• Temperature <100.4°F 2
• Pain controlled with acetaminophen alone (pain score <4/10) 2
• No significant comorbidities or frailty 2
• Immunocompetent status 2
• Adequate home/social support 2

Outpatient management yields 35–83% cost savings without compromising safety. 2

Hospitalization Required For:

• Complicated diverticulitis (abscess ≥4–5 cm, perforation, fistula, obstruction) 2, 6
• Inability to tolerate oral intake 2
• Signs of sepsis or systemic inflammatory response 2
• Immunocompromised status 2
• Significant comorbidities or frailty 2

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Management of Complicated Disease

Small Abscess (<4–5 cm):

• IV antibiotics alone for 7 days 2, 5

Large Abscess (≥4–5 cm):

• CT-guided percutaneous drainage + IV antibiotics 2, 6
• Continue antibiotics for 4 days post-drainage in immunocompetent patients 2

Generalized Peritonitis or Sepsis:

• Emergent surgical consultation 2, 6
• Broad-spectrum IV antibiotics immediately 2

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Follow-Up and Monitoring

Mandatory re-evaluation within 7 days (or sooner if symptoms worsen). 2 Patients should return immediately for:

• Fever >101°F 2
• Severe uncontrolled pain 2
• Persistent vomiting 2
• Inability to eat/drink 2
• Signs of dehydration 2

If symptoms persist beyond 5–7 days, obtain repeat CT to assess for complications. 2

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Post-Acute Management

Schedule colonoscopy 6–8 weeks after symptom resolution for:

• First episode of uncomplicated diverticulitis (if no recent high-quality colonoscopy) 2
• Any complicated episode (7.9% associated cancer risk) 2
• Patients ≥50 years needing routine screening 2

Recurrence prevention measures:

• High-fiber diet (≥22 g/day from fruits, vegetables, whole grains, legumes) 2
• Regular vigorous physical activity 2
• Maintain BMI 18–25 kg/m² 2
• Smoking cessation 2
• Avoid NSAIDs when possible 2
• Do NOT restrict nuts, corn, popcorn, or small-seeded fruits (no evidence of increased risk) 2

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Critical Pitfalls to Avoid

• Do NOT prescribe routine antibiotics for uncomplicated disease without high-risk features—this contributes to antimicrobial resistance without clinical benefit. 2, 4
• Do NOT assume all patients need hospitalization—most immunocompetent patients with uncomplicated disease can be safely managed outpatient. 2
• Do NOT discharge without CT confirmation of uncomplicated disease. 2
• Do NOT overlook immunocompromised patients—they require immediate antibiotics (10–14 days), lower threshold for repeat imaging, and early surgical consultation. 2, 5
• Do NOT stop antibiotics early if indicated—complete the full course even if symptoms improve. 2