How do you diagnose diverticulitis?

Diagnosing Diverticulitis

The diagnosis of diverticulitis should begin with clinical evaluation followed by abdominal CT imaging when there is diagnostic uncertainty in patients with suspected acute left-sided colonic diverticulitis. 1

Clinical Presentation and Initial Assessment

• The most common presenting symptom is abdominal pain, usually acute or subacute in onset and located in the left lower quadrant 1
• Other presenting signs and symptoms include:
  • Fever
  • Change in bowel habits
  • Nausea without vomiting
  • Elevated white blood cell count and/or C-reactive protein (CRP) 1, 2
• Clinical diagnosis alone is correct in only 40-65% of patients, highlighting the need for imaging in many cases 1, 2
• The classic triad of diverticulitis is present in only approximately 25% of patients 2

Diagnostic Imaging

• CT scan of the abdomen and pelvis with oral and intravenous contrast is highly accurate for diagnosing diverticulitis with sensitivity/specificity of 95% 1

• CT imaging is recommended when:

  • Patient has no prior imaging-confirmed diagnosis of diverticulitis 1
  • Severe presentation suggesting complications 1, 2
  • Failure to improve with therapy 1
  • Patient is immunocompromised 1
  • Multiple recurrences, especially if contemplating prophylactic surgery 1
  • Symptom duration before clinical presentation longer than 5 days 1, 2
  • Signs of perforation, bleeding, obstruction, or abscess 1, 2

• Alternative imaging options when CT cannot be obtained:

  • Abdominal ultrasonography (operator dependent, more common in Europe) 1
  • Abdominal MRI when ultrasonography provides inconclusive results (e.g., in obese patients) 1

Diagnostic Pitfalls and Considerations

• Colorectal cancer can mimic both clinical and radiographic findings of diverticulitis 1
• CT findings suggesting colon cancer rather than diverticulitis include:
  • Pericolonic lymphadenopathy (>1 cm in short axis) with or without pericolonic edema 1
• CT findings suggesting diverticulitis include:
  • Inflammatory changes
  • Edema in the root of the sigmoid mesentery
  • No pericolonic lymphadenopathy adjacent to a segment of thickened colon wall 1
• Plain radiographs cannot be used to confirm the diagnosis but are useful in assessing for complications such as perforation or obstruction 1

Follow-up Recommendations

• Colonoscopy is advised after an episode of complicated diverticulitis and after a first episode of uncomplicated diverticulitis 1
• Colonoscopy may be deferred if a recent (within 1 year) high-quality colonoscopy was performed 1
• Colonoscopy should be delayed by 6-8 weeks or until complete resolution of the acute symptoms, whichever is longer 1
• Earlier colonoscopy should be considered if alarm symptoms are present 1
• The risk of colon cancer is higher in patients with complicated diverticulitis (7.9%) compared with patients with uncomplicated diverticulitis (1.3%) 1

Diagnostic Algorithm

1. Clinical assessment for typical symptoms (left lower quadrant pain, fever, change in bowel habits) 1, 2
2. Laboratory evaluation (complete blood count, CRP) 2, 3
3. CT imaging with IV contrast for patients with:
   • First episode of suspected diverticulitis 1
   • Signs of complications 1, 2
   • Immunocompromised status 1
   • Prolonged symptoms (>5 days) 1, 2
4. Classification as complicated or uncomplicated based on imaging findings 4, 3
5. Follow-up colonoscopy 6-8 weeks after resolution of symptoms 1