Vascular anatomical study of persistent descending mesocolon in patients undergoing laparoscopic surgery for colorectal cancer.

Introduction: Persistent descending mesocolon (PDM) is a rare congenital atypia of fixation of the descending colon, and currently, very few detailed studies exist on its vascular anatomy. This study was conducted to evaluate the features of the vascular anatomy of PDM to help avoid intraoperative lethal injury and subsequent postoperative complications in laparoscopic colorectal surgery.

Methods: We retrospectively analyzed the data of 534 patients who underwent laparoscopic left-sided colorectal surgery. PDM was diagnosed using preoperative axial computed tomography (CT) view. The vascular anatomical features were compared between PDM and non-PDM cases based on three-dimensional (3D)-CT angiography findings. Additionally, the perioperative short-term outcomes of laparoscopic surgery in the 534 patients were also compared between PDM and non-PDM cases.

Results: Of the total 534 patients, 13 patients (2.4%) presented with PDM. No branching pattern of the inferior mesenteric artery (IMA) specific to PDM was found. In the running direction of the IMA and sigmoidal colic artery (SA), the midline-shift of IMA and the right-shift of SA were significantly more in PDM than in non-PDM cases, respectively (38.5% vs. 2.5%, P ≤ .0001; 61.5% vs. 4.6%, P ≤ .0001). The perioperative short-term outcomes of laparoscopic surgery in the 534 patients were similar between PDM and non-PDM cases.

Conclusion: Because changes in the direction of the vascular running are often observed due to adhesions and shortening of the mesentery in PDM cases, performing a detailed preoperative evaluation of vascular anatomy using imaging modalities such as 3D-CT angiography is important.