Analyze the occurrence of complications, rectal function and quality of life after anus-preserving surgery for middle and low rectal cancer, so as to evaluate the role of protective ileostomy.

Inclusion Criteria:

Necessary conditions: meet one of the following conditions

1. Difficult pelvis: narrow pelvis (diameter of ischial tuberosity <10 cm, diameter of ischial spine <12 cm) 13 or BMI≥30kg/m2 or tumor diameter≥5cm2.
2. To receive treatment before surgery: preoperative neoadjuvant radiotherapy or concurrent chemoradiation or ESD
3. The anastomosis is below the level of the levator ani muscle: such as ISR, TaTME surgery, etc.

Other conditions:

1. Age: 18 to 75 years old, male or female;
2. Preoperative biopsy pathological diagnosis of rectal adenocarcinoma;
3. Received MRI evaluation before surgery, and the distance between the lower edge of the tumor and the anal edge is no more than 10cm;
4. The clinical stage is T1-3N0-2M0;
5. Undertake elective laparoscopic TME for colon-rectal or colon-anal anastomosis
6. ECOG score 0-2;
7. Heart, lung, liver, and kidney functions can tolerate surgery;
8. Patients and their families can understand and are willing to participate in this clinical study, and sign informed consent.

Exclusion Criteria:

1. Past history of malignant colorectal tumors or recent diagnosis combined with other malignant tumors;
2. Patients with intestinal obstruction, intestinal perforation, intestinal bleeding, etc. who need emergency surgery;
3. Neighboring organs need to be combined with organ removal
4. ASA grade ≥ grade IV and/or ECOG physical status score> 2 points;
5. Those who have severe liver and kidney function, cardiopulmonary function, blood coagulation dysfunction, or combined with serious underlying diseases that cannot tolerate surgery;
6. Have a history of severe mental illness;
7. Pregnant or lactating women;
8. Those with a history of taking hormone drugs;
9. Patients with other clinical and laboratory conditions considered by the investigator should not participate in the trial.

Middle and low rectal cancer patients