To explore various anatomical types and vascular length related factors of inferior mesenteric artery (IMA), and to provide a reference for lower ligation of IMA for colorectal cancer.

The patients who received surgery for colorectal cancer in the First Affiliated Hospital of Wenzhou Medical University from July 2019 to April 2020 were retrospectively analyzed. IMA imaging of inferior mesenteric artery was performed with enhanced CT before operation, and the IMA classification was statistically summarized. In addition, ten adult cadavers from Wenzhou Medical University were dissected by IMA.

There were 172 patients with good filling and good reconstruction effect. According to Murono classification criteria, eighty-eight cases were type Ⅰ, sixty-six cases were type Ⅱ, and 16 cases were type Ⅲ. There were 2 type Ⅳ patients (not included in the statistics). The length of IMA trunk was (42.96±6.78)mm, and there was a certain degree of linear relationship between body weight and IMA trunk length, so body weight was the main influencing factor (coefficient=0.253, P＜0.05). The final equation is IMA trunk length=23.12+0.253×body weight (R²=0.181). The regression equation showed that body weight was positively correlated with IMA dry length, and the average length increased by 0.253 units (mm) for each unit (kg) increase of body weight.

Enhanced CT for IMA can clarify the classification of IMA and the specific vascular conditions, which is helpful to select the location of low ligation. The length of blood vessels can be estimated by BMI, so as to provide the most appropriate way of vascular treatment.