Effect of Carbon Dioxide Insufflation and Appendix on the Restoration of Intestinal Microecology After Colonoscopy.

The goal of this observational study is to learn about Influencing factors of intestinal microecological changes before and after colonoscopy. The main questions it aims to answer are:[question 1] The process of colonoscopic gas insufflation affects the intestinal microecology. Will the use of carbon dioxide gas insufflation can reduce the changes of intestinal microecology after colonoscopy?[question 2] Can the appendix act as a reservoir for microorganisms to accelerate the recovery of intestinal microecology after colonoscopy？Participants will be asked to accept colonoscopy for once. Group 1(Control group) will be insufflated air during the colonoscopy; Group 2(Carbon dioxide group) will be insufflated carbon dioxide during the colonoscopy; Group 3(After appendectomy group) will be insufflated air during the colonoscopy.Since Group 1 is comparison group, the investigators will compare Group 2 to see if carbon dioxide gas insufflation can reduce the changes of intestinal microecology after colonoscopy. Meanwhile, compare Group 3 to see if the appendix can accelerate the recovery of intestinal microecology after colonoscopy.

Inclusion Criteria:Age 18-40 years old, gender is not limited, no underlying diseases;BMI between 18.5-23.9 kg/m2;Fecal Bristol score type III-IV in the past week;No history of alcohol consumption or alcohol consumption equivalent to ethanol should not exceed 140g per week for men and 70g per week for women.Add a criterion to after appendectomy group:Patients who underwent appendectomy in the Department of General Surgery of Zhongshan Hospital Xiamen University within 3 years.Exclusion Criteria:Those who use antibiotics, antifungal drugs, antiviral drugs, probiotics, prebiotics, synbiotics and drugs that may affect the intestinal microecology within 1 month;Those who have acute enteritis or chronic enteritis and other diagnosed chronic bowel diseases in the past 1 month;Those who have digestive symptoms such as blood in the stool, constipation, bloating, abdominal pain, diarrhea and so on in the past 1 monthHistory of digestive surgery (including gastrointestinal polyp resection, gastrointestinal tumor surgery and diversion surgery, etc.).