BackgroundThe diagnostic criteria and effect of persistent descending mesocolon (PDM) on sigmoid and rectal cancers (SRCs) remain controversial. This study aims to clarify PDM patients' radiological features and short-term surgical results.MethodFrom January 2020 to December 2021, radiological imaging data from 845 consecutive patients were retrospectively analyzed using multiplanar reconstruction (MRP) and maximum intensity projection (MIP). PDM is defined as the condition wherein the right margin of the descending colon is located medially to the left renal hilum. Propensity score matching (PSM) was used to minimize database bias. The anatomical features and surgical results of PDM patients were compared with those of non-PDM patients.ResultsThirty-two patients with PDM and 813 patients with non-PDM were enrolled into the study who underwent laparoscopic resection. After 1:4 matching, patients were stratified into PDM (n= 27) and non-PDM (n= 105) groups. The lengths from the inferior mesenteric artery (IMA) to the inferior mesenteric vein (1.6 cm vs. 2.5 cm,p= 0.001), IMA to marginal artery arch (2.7 cm vs. 8.4 cm,p= 0.001), and IMA to the colon (3.3 cm vs. 10.2 cm,p= 0.001) were significantly shorter in the PDM group than those in the non-PDM group. The conversion to open surgery (11.1% vs. 0.9%,p= 0.008), operative time (210 min vs. 163 min,p= 0.001), intraoperative blood loss (50 ml vs. 30 ml,p= 0.002), marginal arch injury (14.8% vs. 0.9%,p= 0.006), splenic flexure free (22.2% vs. 3.8%,p= 0.005), Hartmann procedure (18.5% vs. 0.0%,p< 0.001) and anastomosis failure (18.5% vs. 0.9%,p= 0.001) were significantly higher in the PDM group. Moreover, PDM was an independent risk factor for prolonged operative time (OR = 3.205,p= 0.004) and anastomotic failure (OR = 7.601,p= 0.003).ConclusionPDM was an independent risk factor for prolonged operative time and anastomotic failure in SRCs surgery. Preoperative radiological evaluation using MRP and MIP can help surgeons better handle this rare congenital variant.