Acute Diverticulitis: Presentation and Diagnosis
The correct answers are (b) and (d): Acute diverticulitis presents with acute abdominal pain and fever, and the diagnosis is made by abdominal CT scan. 1
Clinical Presentation
Acute diverticulitis classically presents with left lower quadrant abdominal pain, fever, and leukocytosis—not rectal bleeding. 2, 3, 4 Rectal bleeding is not a typical feature of acute diverticulitis and should prompt consideration of alternative diagnoses such as ischemic colitis, inflammatory bowel disease, or malignancy. 3
Key Clinical Features in Adults Over 40:
- All patients present with abdominal pain, with 67% having left lower quadrant pain specifically 5
- Fever is present in 71% of patients 5
- Leukocytosis occurs in 90% of patients 5
- Associated symptoms include nausea (86%), vomiting, constipation, diarrhea, and dysuria 3, 5
Critical Caveat for Elderly Patients:
Clinical presentation becomes significantly more atypical with advancing age. In patients older than 65 years, only 50% have lower quadrant pain, only 17% have fever, and 43% lack leukocytosis. 1, 2 This atypical presentation leads to misdiagnosis rates of 34-68% based on clinical examination alone in elderly populations. 2, 6
Diagnostic Approach
CT scan of the abdomen and pelvis with IV contrast is the gold standard diagnostic test for acute diverticulitis, with sensitivity of 98-99% and specificity of 99-100%. 1, 7, 4 This imaging modality not only confirms the diagnosis but also distinguishes complicated from uncomplicated disease and excludes alternative diagnoses. 1
Why CT is Superior to Other Modalities:
- Clinical diagnosis alone has insufficient accuracy (sensitivity 0.68, specificity 0.98) and should not be relied upon 1
- Colonoscopy is contraindicated during acute diverticulitis due to risk of perforation; it should be performed 4-6 weeks after symptom resolution for patients with complicated disease or other indications 3
- Ultrasound may be used as an alternative (sensitivity 0.90, specificity 0.90-1.00) when CT is contraindicated, but CT remains preferred 1
CT Findings in Acute Diverticulitis:
- Bowel wall thickening >5mm 7
- Pericolonic fat stranding 7, 8
- Presence of diverticula in the affected segment 9
- Complications visible on CT include abscesses (35% of cases), perforation with free air, fistula formation, and obstruction 7, 8
Treatment Considerations
Corticosteroids are NOT part of the treatment regimen for acute diverticulitis—this makes option (e) incorrect. 1, 4
Actual Treatment Approach:
- Uncomplicated diverticulitis: Observation with pain management (acetaminophen), clear liquid diet, and selective antibiotic use 4
- Antibiotics are reserved for: persistent fever/chills, increasing leukocytosis, age >80 years, pregnancy, immunocompromise, or chronic medical conditions 4
- First-line oral antibiotics: amoxicillin/clavulanic acid or cefalexin with metronidazole 4
- Complicated diverticulitis: IV antibiotics (ceftriaxone plus metronidazole or piperacillin-tazobactam) plus percutaneous drainage for abscesses >4cm or surgical intervention for peritonitis 6, 4
Common Pitfall to Avoid:
Do not assume low inflammatory markers exclude complicated disease. Up to 39% of patients with complicated diverticulitis have CRP <175 mg/L, and 5% of patients with severe diverticulitis present without fever or leukocytosis. 1, 7