What are the investigation and treatment approaches for suspected diverticulitis?

Investigation and Treatment of Suspected Diverticulitis

For patients with suspected diverticulitis, computed tomography (CT) with IV contrast should be obtained as the initial diagnostic imaging modality, followed by appropriate antibiotic therapy for complicated cases or those with specific risk factors. 1, 2

Diagnostic Approach

Initial Imaging

• First-line imaging: CT abdomen and pelvis with IV contrast

  • Sensitivity: 98-99%, Specificity: 99-100% 2, 3
  • Best for detecting complications (abscess, perforation, fistula) 2
  • IV contrast helps characterize and detect subtle bowel wall abnormalities 1
  • Can reduce hospital admissions by >50% and shorten hospital stays 1

• Alternative imaging options:

  • If CT unavailable or contraindicated: Ultrasound or MRI 1
  • For pregnant patients: Ultrasound or MRI (no clear preference between them) 1, 2
  • For premenopausal women: Consider initial pelvic ultrasound if gynecologic pathology suspected 1, 2

• Step-up approach: Ultrasound first, followed by CT if inconclusive or negative, is a safe and effective strategy 1, 4

Clinical Diagnosis Limitations

• Clinical diagnosis alone has a misdiagnosis rate of 34-68% 1, 2
• The classic triad (left lower quadrant pain, fever, leukocytosis) is present in only 25% of patients 1
• Imaging confirmation is necessary in most cases to confirm diagnosis and detect complications 2

Treatment Algorithm

Uncomplicated Diverticulitis (85% of cases)

1. Outpatient management for patients without:

   • Systemic symptoms (persistent fever, chills)
   • Increasing leukocytosis
   • Age >80 years
   • Immunocompromise
   • Pregnancy
   • Significant comorbidities (cirrhosis, CKD, heart failure, poorly controlled diabetes)
   • Inability to tolerate oral intake
   • Lack of social support

2. Treatment components:

   • Pain management (typically acetaminophen)
   • Clear liquid diet initially
   • Selective antibiotic use only for patients with:
     • Comorbidities or frailty
     • Persistent symptoms or vomiting
     • CRP >140 mg/L or WBC >15 × 10^9/L
     • Fluid collection or longer segment of inflammation on CT 2, 3

3. Antibiotic options (if indicated):

   • Oral: Amoxicillin-clavulanate 875/125 mg twice daily for 4-7 days 2, 3
   • Alternative: Cefalexin with metronidazole 3

Complicated Diverticulitis

1. Inpatient management with:

   • IV fluid resuscitation
   • IV antibiotics (ceftriaxone plus metronidazole or piperacillin-tazobactam) 2, 3
   • Surgical consultation

2. Specific interventions based on complications:

   • Abscess ≥3-4 cm: CT-guided percutaneous drainage 2
   • Diffuse peritonitis: Emergent laparotomy with colonic resection 3
   • Localized perforation without drainable collection: Medical therapy 1

Follow-up and Monitoring

• Reassess within 48-72 hours if outpatient management chosen 2
• Monitor for clinical improvement; consider hospitalization if deterioration occurs
• Colonoscopy recommended 6-8 weeks after symptom resolution to exclude malignancy, especially after complicated diverticulitis 2

Important Caveats

• Approximately 5% of uncomplicated cases can progress to complicated diverticulitis 2
• Postoperative mortality varies significantly: 0.5% for elective resection vs 10.6% for emergent resection 3
• Laparoscopic surgery results in shorter hospital stays, fewer complications, and lower in-hospital mortality compared to open colectomy 5
• Early CT can reduce hospital admissions by >50% and shorten hospital stays 1

By following this evidence-based approach to diagnosing and treating suspected diverticulitis, clinicians can optimize patient outcomes while minimizing unnecessary interventions and hospitalizations.