The Role of Pelvic Peritonization in Laparoscopic or Robotic Low Anterior Resection

Inclusion Criteria: * Matching the diagnostic criteria of rectal adenocarcinoma * Laparoscopic or robotic radical surgery for rectal cancer * Preoperative TNM staging T1-3N0-2M0 * No history of malignant tumors by preoperative examination * Middle and low rectal cancer * Tumor size of 4 cm or less * ASA 1-3 scores * Written informed consent by the patient * The patient is willing to randomize to any group Exclusion Criteria: * Previous abdominal surgery * Past malignant tumor history * Preoperative examination suggests distant metastasis * Be participating or have participated in other clinical studies related to rectal cancer surgery within 6 months * Emergency operation Elimination criteria * The tumor is confirmed to be T4b during the operation or other tumors are found to be combined with other tumors during the operation * The anastomosis is located above the peritoneum reflex * Intraoperative conversion to laparotomy * Change the surgical method to perform Miles or Hartmann surgery * Postoperative pathologically confirmed non-adenocarcinoma * The patient asked to withdraw