Inclusion Criteria:  Aged older than 18 years and younger than 85 years. Primary rectal adenocarcinoma confirmed by preoperative pathology result. Expected curative resection via total mesorectal excision procedure. American Society of Anesthesiologists (ASA) class I, II, or III. Written informed consent.  Exclusion Criteria:  Pregnant or breastfeeding women. Severe mental disorder or language communication disorder. Hartmann surgery or colostomy is performed intraoperatively. Interrupted of surgery for more than 30 minutes due to any cause. Malignant tumors with other organs