Robot-assisted surgery for rectal cancer with persistent descending mesocolon: analysis of vascular anatomical features and short-term outcomes

Abstract Purpose Persistent descending mesocolon (PDM) is a rare congenital anomaly characterized by a medial shift of the descending colon and vascular variations that can complicate colorectal surgery. This study aimed to clarify the PDM-associated vascular anatomy and describe the short-term outcomes of robot-assisted surgery. Methods We retrospectively analyzed 541 patients with primary rectal cancer who underwent robot-assisted surgery (2017–2024) and compared the short-term outcomes between the PDM and non-PDM groups. The vascular anatomy, including inferior mesenteric artery (IMA) branching patterns and marginal artery defects, was assessed in 501 patients using preoperative enhanced computed tomography. Results PDM was identified in 22 patients (4.1%) in this study. The short-term outcomes were comparable between the groups. The PDM group had a significantly higher prevalence of radial IMA branching patterns and a higher frequency of marginal artery defects than the non-PDM group (9% vs. 2%). Conclusion PDM is associated with a higher prevalence of radial IMA branching patterns. Marginal artery defects were observed more frequently among patients with PDM; however, this finding requires cautious interpretation because of the small number of affected cases and potential verification bias. Appropriate identification and management of vascular variations may contribute to acceptable short-term outcomes of robot-assisted surgery in patients with PDM.