From the Guidelines
For suspected bowel obstruction, a CT scan of the abdomen and pelvis with IV contrast is the most appropriate imaging modality, as it provides high diagnostic accuracy and valuable information for guiding management, as recommended by the American College of Radiology 1. The use of CT scanning in suspected bowel obstruction has been extensively studied, and the evidence suggests that it is the preferred imaging modality due to its high sensitivity and specificity, as well as its ability to provide detailed information about the location and cause of obstruction, bowel wall viability, and potential complications 1. Some key points to consider when using CT scanning for suspected bowel obstruction include:
- The use of IV contrast is recommended, as it provides valuable information about bowel wall perfusion and potential complications such as ischemia or necrosis 1.
- Oral contrast is not necessary in cases of suspected high-grade obstruction, as the intrinsic fluid and gas within the bowel provide sufficient contrast 1.
- Non-contrast CT may be used in patients with renal impairment, but it may have reduced diagnostic accuracy compared to contrast-enhanced CT 1.
- CT enterography or CT enteroclysis may be useful in cases of suspected intermittent or low-grade obstruction, as they can provide detailed information about the small bowel and help identify the location and cause of obstruction 1. Overall, the evidence suggests that CT scanning is the most appropriate imaging modality for suspected bowel obstruction, and it should be used in conjunction with clinical evaluation and other diagnostic tests to guide management and improve patient outcomes.
From the Research
CT Scanning Modalities for Bowel Obstruction
To determine the appropriate CT scanning modality for possible bowel obstruction, several factors must be considered, including the need for contrast agents and the type of CT scan.
- The study 2 suggests that multidetector computed tomography (MDCT) is commonly used to diagnose bowel obstruction, focusing on confirming the obstruction, determining the transition point, establishing the cause, and seeking signs of complications.
- The use of intravenous contrast agents in abdominal CT scans for bowel obstruction is debated. A study 3 found that the sensitivity of unenhanced CT and enhanced CT was not significantly different in diagnosing small bowel obstruction or large bowel obstruction, suggesting that contrast agents may not always be necessary.
- Another study 4 compared non-enhanced CT (NECT) and enhanced CT (ECT) in evaluating acute small bowel obstruction, finding that both modalities had comparable accuracy in diagnosing mechanical small bowel obstruction.
- The study 5 compared the diagnostic performance of abdominal CT with and without oral contrast in patients with acute nontraumatic abdominal pain, finding that oral contrast was noncontributory to radiological diagnosis in most cases.
- A prospective study 6 used CT-scans and water-soluble contrast medium to manage acute adhesive small bowel obstruction, finding that CT-scans were disappointing in predicting the necessity of emergent laparotomies, but Gastrografin was useful in discriminating between partial and complete small bowel obstruction.
Recommendations for CT Scanning Modalities
Based on the available evidence, the following CT scanning modalities may be appropriate for looking for possible bowel obstruction:
- Multidetector computed tomography (MDCT) 2
- Non-enhanced CT (NECT) or enhanced CT (ECT) 4, depending on the specific clinical scenario and the need for contrast agents
- CT scans without oral contrast 5, as oral contrast is often noncontributory to radiological diagnosis in patients with acute nontraumatic abdominal pain
- The use of water-soluble contrast medium, such as Gastrografin, may be useful in discriminating between partial and complete small bowel obstruction 6