IDDF2024-ABS-0417 A pilot trial: effect of bowel insufflation on gut microbiota of colonoscopy in healthy individuals

<h3>Background</h3> Colonoscopy is the preeminent method in medical diagnostics for the early identification of colorectal carcinoma. Air insufflation is necessary during colonoscopy to provide a clear visual field, and carbon dioxide (CO₂) insufflation has been demonstrated to alleviate the discomfort experienced by patients during the procedure. However, CO₂ may alter the pH in the intestinal tract, thus potentially interfering with the homeostasis of the gut microbiota. In the present study, we enrolled healthy individuals who underwent colonoscopy to validate the impact of carbon dioxide insufflation on the gut microbiota. <h3>Methods</h3> Twenty-four healthy volunteers were recruited and randomly assigned to one of two groups (n = 12 per group): the air insufflation group and the CO₂ insufflation group. Symptoms, including abdominal pain, bloating, diarrhea, and nausea, were recorded. Stool samples were collected at baseline (before bowel preparation), as well as 3, 7, 14, and 28 days post-colonoscopy. The fecal microbiome was assessed using 16S rDNA sequencing to investigate alterations in gut microbiota composition between the two groups. <h3>Results</h3> There were no significant differences in post-colonoscopy symptoms between the air insufflation group and the CO₂ insufflation group. The alpha diversity at day 3 post-colonoscopy showed a significant decrease compared to baseline levels in both the air insufflation group and the CO₂ insufflation group. However, the alpha diversity had been restored to baseline levels by day 7 post-colonoscopy in both groups. There were no significant differences in alpha diversity between the two groups at all time points examined. Moreover, the beta diversity showed no significant difference between the two groups at all time points. At the genus level, compared with baseline, the abundance of enriched bacteria, including Faecalibacterium and Blautia, did not change significantly in both groups on day 3, but there was also a significant decrease in the abundance of <i>Dialister</i> and <i>Clostridia_UCG-014</i>. Importantly, all the above changes returned to baseline levels by 7 days post-colonoscopy. (IDDF2024-ABS-0417 Figure 1. Graphic abstract of the study) <h3>Conclusions</h3> CO₂ insufflation during colonoscopy does not impact the restoration of a patient’s gut microbiome following the procedure and associated bowel preparation.