Effect of gut microbiome on minor complications after a colonoscopy

Background/Aims Minor complications that might occur after colonoscopy, including abdominal discomfort, bloating, diarrhea, and constipation, could a barrier for patients to undergo a screening colonoscopy. In this study, we aimed to identify the effect of gut microbial diversity and composition on minor complications after colonoscopy. Methods A total of 24 healthy subjects provided their stools before bowel preparation and on the 7th and 28th day after colonoscopy. On the 7th day after colonoscopy, the presence of minor complications was investigated using a questionnaire. We divided patients into 2 groups, the no complication group and complications group. The fecal microbial diversity, distribution, and composition were then compared between the groups. Results Five of the 24 subjects reported that they had undergone minor complications after colonoscopy. Most of the symptoms were mild and self-limited, but 1 patient needed medication. Interestingly, the Firmicutes/Bacteroidetes ratio of the initial stool samples before bowel preparation in the complication group was significantly higher than that in no complication group. After bowel preparation, the Firmicutes/Bacteroidetes ratio of the complication group decreased, but not in the no complication group. The microbial diversity of the no complication group decreased after bowel preparation, but not in the complication group. Conclusions The gut microbial composition and diversity before and after bowel preparation could be considered as one of the causes of minor complications after colonoscopy. Further studies are needed to delineate the role of gut microbiota in the occurrence of minor complications after colonoscopy.