From the Guidelines
For suspected small bowel obstruction, CT abdomen with IV contrast is the preferred initial imaging modality, as it provides better visualization of the bowel wall, identification of the transition point of obstruction, and assessment of complications like ischemia or strangulation, according to the most recent and highest quality study 1. The use of IV contrast in CT scans for suspected small bowel obstruction is supported by multiple studies, including a 2020 study published in the Journal of the American College of Radiology, which reported a diagnostic accuracy of more than 90% for CT abdomen and pelvis with IV contrast in patients with suspected high-grade small bowel obstruction 1. Some key points to consider when using CT scans for suspected small bowel obstruction include:
- The use of oral contrast is typically avoided, as it may not progress beyond the obstruction point and could potentially worsen the condition or cause vomiting 1.
- Non-contrast CT can still identify dilated bowel loops and air-fluid levels, but it provides less information about bowel wall viability and vascular complications, and is generally considered an alternative only when IV contrast is contraindicated 1.
- CT scans can help differentiate between complete obstruction of the bowel and facilitate the decision for a trial of non-operative management versus a decision to proceed to surgery, and can also help define the location of the obstruction and identify signs of complications like closed loop, bowel ischemia, and free fluid 1.
From the Research
Diagnostic Approaches for Small Bowel Obstruction
- The use of contrast agents in diagnosing small bowel obstruction has been studied extensively 2, 3, 4.
- A prospective controlled study found that a Gastrografin challenge had a specificity of 96% and a sensitivity of 100% in predicting the need for exploration in patients with small bowel obstruction 2.
- Computed tomography (CT) has also been established as an ideal form of imaging in small bowel obstruction, allowing for the confirmation of obstruction, identification of the site and cause, and detection of strangulation 5, 6.
CT Abdomen with or without Contrast
- There is no direct evidence in the provided studies comparing CT abdomen with contrast to CT abdomen without contrast in the diagnosis of small bowel obstruction.
- However, the use of contrast agents, such as Gastrografin or barium, has been shown to be safe and effective in diagnosing small bowel obstruction and reducing hospital length of stay 2, 3, 4.
- CT scans with contrast may provide additional information on the presence of ischemia or strangulation, which can guide treatment decisions 6.
Recommendations
- The current recommendations for the evaluation of small bowel obstruction include the use of contrast agents, such as Gastrografin or barium, to aid in diagnosis and treatment decisions 2, 3, 4.
- CT scans can be used to confirm the presence of obstruction, identify the site and cause, and detect strangulation 5, 6.
- The choice between CT abdomen with contrast and without contrast may depend on the individual patient's condition and the clinical suspicion of small bowel obstruction.