From the Guidelines
CT with intravenous contrast is the preferred imaging method to rule out diverticulitis, as it enhances visualization of bowel wall inflammation and helps identify complications like abscesses or fistulas, according to the 2024 clinical practice guideline update by the Infectious Diseases Society of America 1. The use of IV contrast can be helpful in characterizing and detecting subtle bowel wall abnormalities and complications of diverticulitis. However, CT without IV contrast may be appropriate in certain situations, such as when IV contrast is contraindicated due to severe renal impairment or contrast allergy. Some key points to consider when using CT to rule out diverticulitis include:
- The importance of IV contrast in enhancing visualization of bowel wall inflammation and complications
- The potential limitations of non-contrast CT in detecting inflammation and complications
- The need for patients to be well-hydrated before receiving IV contrast to protect kidney function
- The typical duration and availability of results for the CT scan It's also worth noting that other imaging modalities, such as MRI or ultrasound, may be used as alternatives in certain situations, but CT with IV contrast remains the preferred method for ruling out diverticulitis, as stated in the 2024 guideline update 1.
From the Research
CT Scan for Diverticulitis Diagnosis
- The use of CT scans with or without contrast for diagnosing diverticulitis has been studied in various research papers 2, 3, 4, 5, 6.
- A study from 1998 found that helical CT with only colonic contrast material is accurate (99%) for confirming or excluding clinically suspected diverticulitis 2.
- A 2024 study compared non-contrast CT vs. contrast-enhanced CT with both intravenous and rectal contrast application for the diagnosis of acute colonic diverticulitis, and found that non-contrast CT is non-inferior to contrast-enhanced CT for the diagnosis of acute colonic diverticulitis 3.
- However, contrast-enhanced CT is associated with significantly higher sensitivities for the presence of an abscess or perforation 3.
Contrast-Enhanced CT
- A 2022 review recommended computed tomography with intravenous contrast as the preferred imaging modality for confirming diagnosis and assessing for complications of diverticulitis 4.
- A 2019 review stated that radiological evidence of inflammation, using computed tomography (CT), is needed to diagnose the first occurrence of diverticulitis, and CT is also warranted when the severity of symptoms suggests that perforation or abscesses have occurred 5.
Non-Contrast CT
- A 2020 study found that the diagnostic accuracy of unenhanced low-dose CT (LDCT) is high for the presence of acute diverticulitis, but signs of complicated disease can be missed using the low-dose protocol 6.
- The study suggested that use of LDCT as a primary examination method should not preclude standard-dose CT (SDCT) when complications may be suspected 6.