What is the next step in managing a patient with suspected diverticulitis, presenting with fever, left lower quadrant pain, abdominal distention, and lab results indicating elevated C-Reactive Protein (CRP) and White Blood Cell (WBC) count, with imaging showing bowel wall thickening and fat stranding?

Management of Acute Diverticulitis

The next step in management for this patient with suspected acute left colonic diverticulitis should be nothing by mouth, IV fluid resuscitation, and IV antibiotics. 1

Clinical Assessment and Diagnosis

This 59-year-old male presents with classic features of acute left colonic diverticulitis (ALCD):

• Initial diffuse abdominal pain localizing to left lower quadrant
• Fever (38.4°C)
• Abdominal distention
• Elevated inflammatory markers (CRP 52 mg/L, WBC 12,000)
• CT findings of bowel wall thickening and fat stranding

These findings are consistent with complicated diverticulitis, likely WSES stage 1a (localized complicated diverticulitis with pericolic air bubbles or small amount of pericolic fluid without abscess) based on the CT description 1.

Management Algorithm

Step 1: Initial Management (Current Priority)

• NPO (nothing by mouth) to rest the bowel
• IV fluid resuscitation to correct potential dehydration
• IV antibiotic therapy targeting common gut flora 1

Step 2: Antibiotic Selection

• Broad-spectrum coverage for gram-negative, gram-positive, and anaerobic bacteria
• Options include:
  • Meropenem IV 2
  • Combination therapy with a fluoroquinolone plus metronidazole
  • Beta-lactam/beta-lactamase inhibitor combinations

Step 3: Monitoring and Reassessment

• Monitor vital signs, abdominal examination, and inflammatory markers
• Reassess within 48-72 hours for clinical improvement 3
• If persistent symptoms of peritonitis or systemic illness beyond 5-7 days, further diagnostic investigation is indicated 1

Rationale for Management Decision

The WSES/SICG/ACOI/SICUT/ACEMC/SIFIPAC guidelines for diagnosis and treatment of acute left colonic diverticulitis (2022) recommend antibiotic therapy for patients with localized complicated diverticulitis 1. The patient's clinical presentation with fever, elevated inflammatory markers, and CT findings indicating complicated diverticulitis necessitates this approach.

The 2020 WSES guidelines specifically state: "We suggest antibiotic therapy administration for patients with localized complicated left colonic diverticulitis with pericolic air bubbles or little pericolic fluid without abscess" 1.

Why Other Options Are Not Appropriate

1. Surgical consult for exploratory laparoscopy: Not indicated as first-line management for uncomplicated or localized complicated diverticulitis without evidence of diffuse peritonitis or large abscess 1. Surgery should be reserved for patients with diffuse peritonitis, large abscesses not amenable to percutaneous drainage, or failed medical management.

2. Gastric decompression, IV fluids: Insufficient alone without antibiotics for complicated diverticulitis 1.

3. Colonoscopy: Contraindicated in acute diverticulitis due to risk of perforation 1. Colonoscopy should be performed 6-8 weeks after resolution of acute symptoms to exclude malignancy 3.

Special Considerations

• CRP levels: The patient's CRP of 52 mg/L suggests complicated diverticulitis but is below the threshold of 150-200 mg/L that would strongly indicate perforation 4. This supports medical management rather than immediate surgical intervention.

• Monitoring for deterioration: About 5% of cases can progress to more severe disease, requiring close monitoring 3.

• Duration of antibiotics: A short course (3-5 days) is reasonable after adequate source control in complicated diverticulitis 1.

Common Pitfalls to Avoid

1. Relying solely on clinical examination: Diagnosis of diverticulitis based only on clinical findings lacks accuracy, with positive predictive values of only 0.65 1. CT confirmation is essential.

2. Premature colonoscopy: Performing colonoscopy during acute inflammation increases perforation risk 1.

3. Delaying antibiotics: For complicated diverticulitis, prompt antibiotic therapy is essential to prevent progression to more severe disease 1.

4. Overlooking alternative diagnoses: CT findings of pericolonic lymphadenopathy should raise suspicion for colon cancer rather than diverticulitis 1.

By following this evidence-based approach with prompt medical management including bowel rest, IV fluids, and appropriate antibiotics, the patient has the best chance for clinical improvement while avoiding unnecessary invasive procedures.