This study aims to propose a novel, easy-to-operate intervention strategy that effectively improves defecation function after stoma reversal and to assess its impact on the gut microbiota.The efficacy and safety of antegrade placement of probiotics into the distal deserted intestine during prophylactic stoma to improve bowel function after stoma reversal were evaluated through randomized controlled clinical trials.Observing the changes in gut microbiota during the prophylactic stoma period, the impact of probiotics on the structure of gut microbiota, and exploring the correlation between gut genera and bowel function after stoma reversal.

This study includes patients with ultra low rectal cancer who underwent ISR（Intersphincteric Resection） and prophylactic ileostomy. Patients are randomly assigned to the low dose group,high dose group and the control group in a 1:1:1 ratio. The low dose group received interventions (4 Meiya pills, administered into the dysfunctional intestine once a week) starting 1 week after the ileostomy, the high dose group received interventions (4 Meiya pills, administered into the dysfunctional intestine twice a week) starting 1 week after the ileostomy, while the control group received routine postoperative follow-up. Evaluation indicators included bowel function and quality of life before the prophylactic ileostomy and 1 week, 2 weeks, 1 month, 3 months, and 6 months and so on until two years after the stoma reversal.

Fecal samples are collected prior to prophylactic ileostomy. Post-stoma reversal surgery, fecal samples are obtained from patients at their first defecation . All fecal samples underwent 16s rRNA gene sequencing and bioinformatic analysis to compare the microbial composition differences among three groups. Key genera associated with bowel function were identified through correlation analysis.

Inclusion Criteria:

1. Age between 18 and 75 years
2. Ultra low rectal cancer meeting the indication for Intersphincteric Resection (ISR) surgery
3. Underwent a prophylactic ileostomy
4. Scheduled for stoma reversal surgery within 6 months after the ISR procedure
5. Digestive tract reconstruction achieved via either hand-sewn or stapled coloanal anastomosis
6. Patient has a strong preference for undergoing sphincter-preserving surgery
7. Capable of understanding and willing to provide signed informed consent

Exclusion Criteria:

1. Does not meet the surgical indications for Intersphincteric Resection (ISR)
2. Presence of multiple primary colorectal malignancies
3. Patients who have received neoadjuvant radiotherapy
4. Patients who experience disease progression or death in the postoperative period
5. Patients who develop severe anastomotic complications postoperatively, such as anastomotic leakage or stenosis
6. Patients whose actual stoma reversal surgery occurs more than 6 months after the ISR procedure
7. Patients who require long-term(more than 3 months) use of antibiotics
8. History of allergy to Clostridium butyricum (live) Tablets (MIYA) or any of its components
9. Concurrent use of other probiotic during the study period
10. Coexisting inflammatory bowel disease
11. History of neurological or psychiatric disorders, including but not limited to Parkinson's disease, Alzheimer's disease, organic brain diseases, stroke, epilepsy, or major psychiatric disorders (e.g., major depressive disorder)
12. Pregnant or lactating women

De-identified individual participant data that underlie the results reported in this article (text, tables, figures, and appendices) will be shared. The study protocol, statistical analysis plan, and informed consent form will also be available. Data will be available beginning 9 months and ending 36 months after article publication. Proposals for data access should be directed to the corresponding author. To gain access, data requestors will need to sign a data access agreement. Data will be provided via a secure online platform.

Data will be available beginning 9 months and ending 36 months after article publication.

De-identified individual participant data will be available to qualified researchers whose proposals have been approved by an independent data access committee. Requestors must submit a scientifically sound research proposal and sign a data use agreement.