From the Guidelines
A CT scan is not typically the first-line imaging choice for diagnosing gastroenteritis or colitis, but it may be useful in certain situations, such as when complications like perforation, abscess, or severe disease are suspected, or when other diagnoses like diverticulitis or appendicitis are being considered 1.
Key Considerations
- For suspected gastroenteritis, diagnosis is generally made clinically based on symptoms like diarrhea, vomiting, abdominal pain, and fever, and laboratory tests such as stool cultures or PCR testing are more appropriate than imaging.
- For colitis (inflammation of the colon), a colonoscopy with biopsies is the preferred diagnostic method as it allows direct visualization of the intestinal mucosa and tissue sampling.
- CT scans may be used to evaluate the severity of disease, detect complications, and guide management decisions, particularly in cases of suspected diverticulitis or other conditions that may require surgical intervention 2, 3.
CT Findings in Colitis
- CT findings in colitis may show bowel wall thickening, mucosal enhancement, and surrounding inflammatory changes, but these findings are nonspecific.
- The sensitivity and specificity of CT imaging for diagnosing colitis or diverticulitis can vary, but it is generally high for detecting complications like abscesses or perforation 2.
Clinical Decision-Making
- If gastroenteritis or colitis is suspected, consult with a healthcare provider who can determine the appropriate diagnostic approach based on symptom severity, duration, and other clinical factors.
- The use of CT imaging should be guided by clinical judgment and consideration of the potential benefits and risks, including radiation exposure and the possibility of incidental findings 3, 1.
From the Research
Gastroenteritis and CT Scan Colitis
- The use of CT scans in patients with gastrointestinal complaints, including gastroenteritis and colitis, is a common practice in emergency departments 4, 5.
- A study published in 2015 found that CT scans had no clinically significant findings in 63.2% of patients with ulcerative colitis, and less than 2% of scans revealed complications related to the disease 4.
- Another study published in 2022 found that CT scans had a low sensitivity, specificity, and negative predictive value for the diagnosis of immunotherapy-induced colitis, suggesting a limited role in diagnosis 6.
CT Findings in Colitis
- CT findings suggestive of colitis include mucosal enhancement, wall thickening, distension, and periserosal fat stranding 6, 7.
- A study published in 2017 found that CT scans can detect large bowel perforation, which can be a complication of colitis, by identifying direct findings such as extraluminal gas or contrast and discontinuity along the bowel wall 7.
- Indirect CT findings, such as bowel wall thickening and pericolic fat stranding, can also support the diagnosis of colitis 7.
Role of Oral Contrast in CT Scans
- A study published in 2017 found that oral contrast is not necessary for CT scans in patients with acute nontraumatic abdominal pain, including those with colitis, and that the lack of oral contrast did not affect radiological diagnostic performance 8.
- The study found that oral contrast was helpful in only 3.4% of cases, and that CT scans without oral contrast were technically adequate in all cases 8.
Predictors of Clinically Significant CT Findings
- A study published in 2015 found that predictors of clinically significant CT findings in patients with ulcerative colitis included nausea and vomiting, history of colectomy, history of abdominal or pelvic surgery, surgery within 1 month, age, elevated white blood cell count, and no UC medications 4.
- The study also found that predictors of CT scans without clinically significant findings included rectal bleeding or diarrhea, use of 5-aminosalicylate, or immunomodulator 4.