A vascular typing study based on superior mesenteric artery and vein variations that can reflect the extent of right colon lymphatic drainage and evaluate the difficulty of surgery

Interventions: experimental group:SMA-guided lymph node dissection;control group:SMV-guided lymphatic dissection
Primary outcome(s): Operation time;Amount of bleeding;Conversion rate of laparotomy;Number of lymph nodes obtained;First anal exhaust time;First time out of bed;Drainage flow of drainage tube;indwelling time of drainage tube;Incidence of postoperative short-term complications;Rate of re-hospitalization 30 days after surgery;Rate of mortality 30 days after surgery;Local recurrence rate;Median disease-free survival time;Median overall survival time
Study Design: Case-Control study