Transanal drainage tube (TDT) has the benefit of reducing intraluminal pressure after rectal surgery and may provide ideal regional environment for anastomotic healing. Postoperative C-reactive protein (CRP) trajectory has a high negative predictive value of 0.99 for ruling out anastomotic leak (AL). Previously, TDT was removed at the surgeon's own discretion. In the present study, we design a single arm study to investigate the safety and efficacy of CRP-guided TDT removal for AL prevention following laparoscopic anterior resection for rectal carcinoma

Inclusion Criteria:

• age from 18 to 75 years old
• male and female
• primary rectal adenocarcinoma
• ASA I, II, or III
• laparoscopic LAR + DST
• with or without preoperative radio- or chemotherapy
• no distal metastasis
• no preoperative bowel obstruction
• no preventive ileostomy or colostomy
• patients and their families can understand and are willing to participate in this study and provide written informed consent

Exclusion Criteria:

• emergency operation
• preoperative abnormal liver function
• tatme or ISR procedure (healing process might differ from anterior resection)
• severe postoperative (Clavien-Dindo grade III IV V) complications other than anastomotic leak
• severe perioperative infection unrelated to anastomotic leak
• patients with serious mental illness
• pregnant or breastfeeding women
• patients with other clinical and laboratory conditions considered by the investigator should not participate in the trial