From the Guidelines
Computed tomography (CT) with intravenous contrast is the preferred imaging modality for diagnosing diverticulitis. When a patient presents with symptoms suggestive of diverticulitis (lower abdominal pain, fever, altered bowel habits), a contrast-enhanced CT scan of the abdomen and pelvis should be performed to confirm the diagnosis and assess disease severity 1. The CT scan can identify diverticular inflammation, abscess formation, perforation, or other complications that may require surgical intervention.
Key Points
- CT is the most useful examination for patients with suspected complications of colonic diverticulitis due to its reproducibility, superior diagnostic accuracy, and ability to demonstrate other causes of left lower quadrant pain that mimic diverticulitis 1.
- IV and oral contrast material may improve diagnosis of abscess by distinguishing from adjacent bowel 1.
- Unenhanced CT with oral contrast is less accurate than contrast-enhanced CT with oral contrast for the characterization of complications of diverticulitis but is superior to unenhanced CT without oral contrast 1.
- CT can predict unfavorable outcomes from acute diverticulitis, including longer segments of involved colon, retroperitoneal abscess, and extraluminal air 1.
Alternative Imaging Modalities
- Ultrasound may be used as an alternative in pregnant patients or those who cannot undergo CT scanning, though it is less sensitive and more operator-dependent 1.
- Magnetic resonance imaging (MRI) can be considered in pregnant patients or those with contraindications to CT, but is less commonly used 1.
- Plain radiographs have limited utility and are not recommended as the primary imaging modality.
- CT colonography and barium enema studies are contraindicated in acute diverticulitis due to the risk of perforation.
Importance of Prompt Imaging
- Prompt imaging is important as it guides treatment decisions, including whether the patient can be managed as an outpatient with oral antibiotics or requires hospitalization, intravenous antibiotics, percutaneous drainage of abscesses, or surgical intervention 1.
From the Research
Imaging Modalities for Diverticulitis
- Computed Tomography (CT) is a highly sensitive and specific modality for the diagnosis of acute diverticulitis and its complications 2, 3, 4, 5, 6
- Ultrasound (US) can be used to diagnose diverticulitis, especially in cases where CT is not available or contraindicated 2, 4
- Magnetic Resonance Imaging (MRI) and virtual CT colonoscopy have adjunct roles for screening and workup of complications in specific patient populations 4
CT Findings in Diverticulitis
- Edematous thickening of the bowel wall with inflammatory changes within the adjacent mesenteric fat 2
- Localized inflammation surrounding a diverticulum, ranging from wall thickening and phlegmonous change to the development of small, localized pericolic abscesses 4
- Complicated forms of disease manifest with larger pericolic and distant abscesses, fistulae to adjacent organs, perforation, and peritonitis 2, 4, 5
Classification of Diverticulitis
- Uncomplicated diverticulitis: characterized by localized inflammation surrounding a diverticulum, with no complications 3, 4, 5
- Complicated diverticulitis: characterized by the presence of complications such as abscesses, fistulae, perforation, and peritonitis 3, 4, 5, 6
- A radiological classification system divides acute colonic diverticulitis into two groups: complicated and uncomplicated, with further subdivision of complicated diverticulitis into four stages 5