The role of variant anatomy of the left colon artery and inferior mesenteric vein in planning resections of the left colon for colorectal cancer

During laparoscopic surgery, vascular arrangements and variations can be misidentified and injured because of the lack of tactile sensation and narrowed view, resulting in complications such as massive bleeding and bowel ischemia. Therefore, preoperative awareness of the vessels anatomical variations is of the utmost importance so that preoperative strategies can be applied to ensure safe and rapid vessel ligation and lymph node dissection. Aim: development of a classification of variability of the left colon artery (LCA), inferior mesenteric vein (IMV) for practical use in operations for colorectal cancer. Materials and methods: 214 CT - studies of the abdominal cavity with intravenous contrast were analyzed from 2013 to 2021 year. The variant anatomy LCA and IMV was studied. The trajectory of the LCA was studied. Results: in 54% patients, the LCA arose independently from the sigmoidal trunk (SA) (type A); in 25% patients, the LCA and SA arose from the inferior mesenteric artery (IMA) at the same point (type B); in 20% patients, the LCA and SA had a common trunk (type C); the LCA did not exist in 1% (type D). 73.83% of the LCA went straight upper left and upward to proximal part of descending colon (type I), 26.17% went to the lower left at first, then turned to travel straight upward to proximal part of descending colon (type II). The IMV drained into the superior mesenteric vein (SMV) in 47 patients, into the confluence point of the SMV and splenic vein (SV) in 55 patients, into the SV in 109 patients, and into the middle colic vein (MCV) in the remaining three patients. Conclusions: 3D-CT angiography is useful for the preoperative assessment of vascular anatomical variations of the IMV and IMA, LCA for safe intraoperative navigation and prevention of complications during left-sided colorectal surgery.