What are the diagnostic criteria for diverticulitis?

Diagnostic Criteria for Diverticulitis

Diverticulitis is best diagnosed through a combination of clinical symptoms, laboratory findings, and imaging studies, with CT scan being the most accurate diagnostic tool with 98% sensitivity and specificity for confirming the diagnosis and assessing complications. 1

Clinical Presentation

• Primary symptoms:

  • Left lower quadrant abdominal pain (most common presentation)
  • Fever
  • Nausea and vomiting
  • Change in bowel habits (constipation or diarrhea)

• Physical examination findings:

  • Tenderness in left lower quadrant
  • Abdominal distention or rigidity
  • Possible palpable mass

Laboratory Findings

• Key laboratory tests:

  • Elevated white blood cell count (leukocytosis)
  • Elevated C-reactive protein (CRP) > 50 mg/l (important marker)
  • Basic metabolic panel to assess renal function
  • Urinalysis to rule out urinary causes

• Clinical prediction rule: A clinical diagnosis is more likely with the combination of:

  1. Direct tenderness only in left lower quadrant
  2. CRP > 50 mg/l
  3. Absence of vomiting 1

Imaging Studies

• CT scan with intravenous contrast:

  • Gold standard diagnostic test (98-99% sensitivity, 99-100% specificity) 2
  • Can identify complications such as abscess, perforation, or fistula
  • Findings include:
    • Colonic wall thickening
    • Pericolonic fat stranding
    • Presence of diverticula
    • Possible abscess or extraluminal air 1

• Ultrasound:

  • Alternative when CT is contraindicated
  • Diagnostic criteria include:
    1. Short-segment colonic wall thickening (>5 mm)
    2. Inflamed diverticulum in thickened area
    3. Noncompressible hyperechoic pericolic tissue 1
  • Less accurate in obese patients or distal sigmoid diverticulitis

Classification of Diverticulitis

• Uncomplicated diverticulitis:

  • Inflammation limited to colonic wall and surrounding tissue
  • No abscess, perforation, fistula, or obstruction

• Complicated diverticulitis:

  • Pericolic air bubbles or small amount of pericolic fluid
  • Abscess formation (≤4 cm or >4 cm)
  • Distant gas (>5 cm from inflamed bowel)
  • Diffuse fluid with or without distant free gas 1

Diagnostic Pitfalls to Avoid

1. Relying solely on clinical diagnosis: Clinical diagnosis alone has limited accuracy with a positive predictive value of only 0.65 1

2. Failing to differentiate from other conditions: Diverticulitis can mimic other conditions including:

   • Colorectal cancer (especially perforated cancer)
   • Inflammatory bowel disease
   • Ischemic colitis
   • Appendicitis (especially with right-sided diverticulitis)

3. Missing complications: CT is essential for identifying complications that may require surgical or interventional management 1

4. Overlooking colon cancer: CT findings that suggest colon cancer rather than diverticulitis include pericolonic lymphadenopathy (>1 cm) with or without pericolonic edema 1

Management Considerations Based on Diagnosis

• Uncomplicated diverticulitis:

  • Can often be managed as outpatient with observation and pain management
  • Antibiotics reserved for patients with systemic symptoms, increasing leukocytosis, age >80 years, pregnancy, immunocompromise, or chronic medical conditions 2

• Complicated diverticulitis:

  • Requires hospitalization, IV antibiotics, and possible interventional procedures
  • Abscesses ≥3 cm should be treated with percutaneous drainage
  • Surgical intervention for perforation with peritonitis 3

By following these diagnostic criteria and being aware of potential pitfalls, clinicians can accurately diagnose diverticulitis and initiate appropriate treatment to reduce morbidity and mortality associated with this common condition.