Somatostatin Plus Clear Liquid Diet Versus Diverting Stoma in Patients With Rectal Cancer Undergoing Ultra-Low Anterior Resection

Inclusion Criteria: 1. Adults aged 18 to 75 years 2. Patients with stage I to III rectal malignancy who are scheduled to undergo low anterior resection at a participating gastrointestinal surgery center 3. The lower edge of the tumor is 8 cm or less from the dentate line, or 10 cm or less from the anal verge, based on preoperative colonoscopy, imaging, or digital rectal examination 4. The planned anastomosis is expected to be 2 cm or less from the dentate line, or 4 cm or less from the anal verge 5. Patients have two or more risk factors for anastomotic leakage as assessed by the study team 6. American Society of Anesthesiologists physical status classification is grade 3 or lower 7. Body mass index is less than 30 kg/m² 8. The patient, or the patient's legally authorized representative, is willing and able to provide written informed consent Exclusion Criteria: 1. Has another colorectal malignant tumor at the same time 2. The final anastomosis after surgery is more than 2 cm from the dentate line, or more than 4 cm from the anal verge 3. Has metastatic disease before surgery 4. Is pregnant 5. Has a mental illness or addictive disorder that would prevent participation in the clinical trial 6. Requires emergency surgery 7. Has inflammatory bowel disease 8. Is allergic to somatostatin or is unable to tolerate somatostatin 9. For participants assigned to the no-stoma group, the surgeon decides that a stoma is required 10. Has received neoadjuvant drug therapy less than 2 weeks before surgery, or radiotherapy less than 8 weeks before surgery 11. Has any other condition that makes it impossible to follow the study protocol