What is the recommended management of an acute episode of sigmoid diverticulitis in a hemodynamically stable patient without peritonitis or a large (>4 cm) abscess?

Management of Acute Sigmoid Diverticulitis

Immediate Diagnostic Confirmation

Contrast-enhanced CT of the abdomen and pelvis is mandatory for all hemodynamically stable patients with suspected acute sigmoid diverticulitis, because clinical examination alone has only a 65% positive predictive value and CT imaging improves diagnostic accuracy to 95-99%. 1, 2

• CT with IV contrast is required to distinguish uncomplicated from complicated disease and to detect abscess, perforation, or distant free gas that dictate stage-specific therapy. 2
• The only exception: imaging may be omitted in patients with a prior CT-confirmed episode who present with mild, recurrent symptoms matching their previous attacks. 2
• Ultrasound is an acceptable alternative when CT is unavailable or contraindicated (e.g., pregnancy), though it is operator-dependent. 3, 4

Classification Using the WSES System

Apply the World Society of Emergency Surgery (WSES) classification to stratify disease severity and guide treatment decisions. 1, 2

Stage 0: Uncomplicated Diverticulitis

CT findings: Diverticula with bowel wall thickening and increased pericolic fat density, without abscess, perforation, free gas, or distant complications. 1, 2

Management:

• Immunocompetent patients without significant comorbidities should be managed as outpatients with observation, acetaminophen for pain, and a clear-liquid diet; routine antibiotics are NOT required. 2
• Outpatient eligibility requires: ability to tolerate oral intake, reliable follow-up within 48-72 hours, and absence of systemic signs (persistent fever, chills, rising leukocyte count). 2
• Antibiotics do not improve outcomes in uncomplicated disease and contribute to antimicrobial resistance. 2

Stage 1A: Pericolic Micro-perforation

CT findings: Pericolic air bubbles or small fluid collection ≤5 cm from the inflamed bowel segment. 1, 2

Management:

• Admit for hospital observation and administer IV broad-spectrum antibiotics covering gram-negative and anaerobic organisms. 2
• No percutaneous drainage is required. 2

Stage 1B: Small Abscess (≤4 cm)

CT findings: Abscess ≤4 cm in diameter. 1, 2

Management:

• IV antibiotics for 7 days with hospital admission. 2
• Drainage is generally not needed. 2

Stage 2A: Large Abscess (>4 cm)

CT findings: Abscess >4 cm in diameter. 1, 2

Management:

• IV broad-spectrum antibiotics PLUS percutaneous CT-guided drainage. 2, 3
• Continue antibiotics for 4 days if source control is adequate in immunocompetent patients; extend to 7 days for immunocompromised or critically ill individuals. 2

Stage 2B: Distant Free Gas

CT findings: Free intraperitoneal gas >5 cm from the inflamed bowel segment. 1, 2

Management:

• Start IV antibiotics immediately and obtain urgent surgical consultation. 2
• Consider percutaneous drainage if an accessible abscess is present. 2
• Critical pitfall: Non-operative management fails in 57-60% of cases when large volumes of distant free air are present. 2

Stage 3: Diffuse Intra-abdominal Fluid Without Distant Free Gas

CT findings: Diffuse fluid (purulent peritonitis) without distant free gas. 1, 2

Management:

• IV antibiotics and surgical consultation. 2
• Perform percutaneous drainage if an abscess is identified. 2

Stage 4: Generalized Peritonitis

CT findings: Diffuse fluid with distant free gas (fecal or purulent peritonitis). 1, 2

Management:

• IV antibiotics AND urgent surgical intervention; laparoscopic approach is preferred when feasible. 2
• Post-operative mortality after emergent resection for generalized peritonitis is approximately 10.6%, compared with 0.5% for elective resection. 1

Critical Red Flags Requiring Immediate Surgery

• Fecal peritonitis on imaging mandates emergent surgical management. 2
• Diffuse peritonitis with hemodynamic instability requires immediate operative intervention. 2

Common Pitfalls to Avoid

• Never perform colonoscopy during acute diverticulitis—wait 6-8 weeks after resolution to avoid perforation risk. 3
• Routine colonoscopy after CT-confirmed uncomplicated diverticulitis is unnecessary unless the patient is due for age-appropriate screening or imaging reveals complications (abscess, perforation, fistula, abnormal lymph nodes, or a mass). 2
• Pericolonic lymphadenopathy >1 cm on CT should raise suspicion for colonic carcinoma masquerading as diverticulitis. 2
• Do not rely on clinical examination alone—CT imaging is essential for accurate diagnosis and staging. 3

Special Considerations

• Pelvic pressure pain may signal a pelvic abscess (Stage 1B or 2A); CT assessment of abscess size guides the need for drainage. 2
• In premenopausal women, obtain a β-hCG test before CT and consider pelvic/transvaginal ultrasound to exclude gynecologic emergencies (ovarian torsion, tubo-ovarian abscess, ectopic pregnancy). 2

Elective Surgery Timing

• If elective resection is indicated, schedule it 6-8 weeks after resolution of the acute episode; the decision should be based on disease severity and patient comorbidities rather than on the number of prior episodes. 2