What is the recommended approach for a CT abdomen with IV and oral contrast to exclude a bowel leak?

From the Guidelines

The use of oral contrast in a CT abdomen with IV contrast to exclude a bowel leak is not substantially beneficial, as studies have shown that CT-scan alone has a high sensitivity and specificity for depicting bowel injuries [42,102,110-123]. When considering the approach for a CT abdomen with IV contrast to exclude a bowel leak, it is essential to prioritize the patient's safety and the diagnostic accuracy of the procedure.

• The administration of IV contrast (typically 100-150 mL of iodinated contrast material like iohexol or iopamidol) via peripheral venous access at a rate of 2-3 mL/second immediately before scanning is recommended, with images acquired during the portal venous phase (approximately 70-90 seconds after injection) 1.
• The patient should be positioned supine with arms raised above the head, and scanning should extend from the diaphragm through the symphysis pubis with thin collimation (≤5 mm).
• A repeat CT-scan 12–48 h after admission in doubtful cases of pancreatic-duodenal lesions should be considered, as the follow-up scan sensitivity for bowel perforation increases from 30 to 82% 1.
• The use of MRI with hepatobiliary contrast agents or MRCP may be considered in specific cases, such as assessing common bile duct/ampulla injury or localizing associated bile leaks 1. However, the primary approach for excluding a bowel leak should focus on the use of IV contrast and careful imaging technique, rather than relying on oral contrast.

From the Research

CT Abdomen with IV and Oral Contrast for Bowel Leak Detection

• The use of oral contrast in CT abdomen scans for detecting bowel leaks is a topic of discussion among medical professionals.
• A study published in 2000 2 found that using a combination of diluted iodine solution and water as oral contrast agents can effectively opacify the distal small bowel and stomach, making it easier to detect abnormalities.
• However, a study published in 2007 3 compared the effectiveness of CT scans and water-soluble enemas in detecting postoperative lower gastrointestinal anastomotic leaks and found that water-soluble enemas were more effective, especially for distal anastomotic leaks.

Diagnostic Performance of CT Scans

• A study published in 2018 4 evaluated the diagnostic performance of CT scans in identifying anastomotic leaks and found that the use of intraluminal contrast agent was highly specific and improved diagnostic performance.
• The study found that the most sensitive imaging predictor was intraabdominal free fluid, while leakage of intraluminal contrast agent was a highly specific predictor.
• Another study published in 2017 5 found that oral contrast was not necessary for most patients presenting with acute nontraumatic abdominal pain, but this study did not specifically focus on bowel leak detection.

Recommendations for CT Abdomen with IV and Oral Contrast

• Based on the available evidence, it appears that the use of oral contrast in CT abdomen scans for detecting bowel leaks may be beneficial, especially when combined with intravenous contrast.
• The choice of oral contrast agent and the timing of its administration may also be important factors to consider.
• Further research is needed to determine the optimal approach for using CT scans with IV and oral contrast to exclude bowel leaks.