Perfusion Outcomes With Near Infrared-Indocyanine Green Imaging System in Laparoscopic Total Mesorectal Excision for Mid- or Low-rectal CanceR

Inclusion Criteria:

* The age was over 18 years at the time of diagnosis;
* Diagnosis of rectal carcinoma and was confirmed by preoperative pathology;
* MRI was performed before operation, and the distance between the lower margin of tumor and the anal margin was no more than 10cm;
* The colon-rectum or colon-anus anastomosis was performed by laparoscopic TME operation
* The "spleen area" was not free during the operation
* Baseline clinical tumor stage TNM Ⅰ-Ⅲ phase: cT1-4N0-2M0 （AJCC-8 version）;

Exclusion Criteria:

* Allergic to ICG or iodine;
* Patients with intestinal obstruction, intestinal perforation, intestinal bleeding who need emergency operation;
* Patients requiring combined organ resection that the tumor involves adjacent organs;
* Patients with recurrence of tumor or distant metastasis;
* Patients with multiple colorectal cancer;
* Patients with history of inflammatory bowel disease or familial adenomatous polyposis;
* Patients who have participated in or are participating in other clinical trials in the past four weeks;
* Patients that ASA level is larger than III;
* Physical condition: Patients with KPS less than or equal to 60 points or ECOG larger than or equal to 2 points;
* Patients with hepatic dysfunction and MELD larger than 12 points;
* Patients with a history of serious mental illness;
* Pregnant or lactating women;
* Patients who are improper to participate in the study in the opinion of the researchers.