Purpose or Case Report: Choice of contrast for pediatric upper gastrointestinal series (UGI) is variable. While radiologists prefer the density of barium, surgeons prefer water soluble contrast. Diluting water-soluble contrast makes it nearly iso-osmotic, reducing the risk of electrolyte disturbance, but does dilution impair diagnostic accuracy? Does the contrast agent affect duodenal distention? Does the amount of bowel gas affect perceived density?
Methods & Materials: From 9/9/24-9/8/25, there were 142 UGI on children 2 years old or less. A 5-point Likert scale assessed the amount of bowel gas, density of contrast, and duodenal distention. Contrast types (barium; n=99, iohexol 300 or 350 mgI/mL; n=33, or iohexol 300/350 diluted 1:1 with sterile water; n=10) and surgical outcomes were documented. We compared contrast types with density and duodenal distention. We compared the amount of bowel gas on the scout image with contrast density. We compared the amount of bowel gas on the scout image with contrast density. Data analysis was performed using an AI-assisted workflow (Microsoft Copilot with Python execution). The AI tool facilitated non-parametric statistical testing (Kruskal-Wallis and Mann-Whitney U), correlation analysis (Spearman), and visualization (boxplots and scatterplots) for quality metrics in pediatric fluoroscopic upper GI studies. All outputs were reviewed and validated by the research team for accuracy and clinical relevance.
Results: Dilute iohexol was significantly less dense than barium (p=0.0001) and undilute iohexol (p=0.0045), but there was no difference between barium and undilute iohexol (p=0.9897). Bowel distention was not significantly different between barium and iohexol (p=0.530). Bowel gas did not affect density assessment. Two important false negative studies were performed with dilute iohexol; one missed volvulus and one missed duodenal obstruction confirmed as a duodenal web at surgery. There was one false positive study with barium; a diagnosis of malrotation without volvulus due to a low duodenal-jejunal junction on UGI was incorrect with normal anatomy at surgery.
Conclusions: Dilute iohexol contrast is significantly less dense and may result in false negative studies regarding emergent diagnoses. Determination of contrast agent, barium or non-dilute iohexol, should be made in conjunction with the clinical team since fluid and electrolyte balance may be affected. Bowel gas does not affect contrast density. The type of contrast does not affect duodenal distention.