Inclusion Criteria:  Age between 18 and 75 years American Society of Anesthesiologists (ASA) score I to III A biopsy proven histological diagnosis of rectal carcinoma Undergoing transanal total mesorectal excision  Exclusion Criteria:  Pregnant or lactating women Synchronous rectal carcinoma History of colorectal cancer or other malignant tumors Clinical evidence of metastasis Emergency procedure