Background The 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. Method From 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. Results Thirty-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). Conclusion PDM 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.

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Background The 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. Method From 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; this is usually proved intraoperatively. The anatomical features and surgical results of PDM patients were compared with those of non-PDM patients. Results The frequency of PDM was 3.8%. The lengths from the inferior mesenteric artery (IMA) to the inferior mesenteric vein (1.6 vs. 2.5 cm, p＜0.001), IMA to marginal artery arch (2.7 vs. 8.4 cm, p＜0.001), and IMA to the colon (3.5 vs. 9.8 cm, p＜0.001) were significantly shorter in the PDM group than those in the non-PDM group. The conversion to open surgery (12.5% vs. 1.2%, p=0.001), operative time (207.5 vs. 156 min, p=0.001), intraoperative blood loss (p＜0.001), marginal arch injury (15.6% vs. 1.1%, p＜0.001), splenic flexure free (21.9% vs. 3.3%, p＜0.001), and Hartmann procedure (15.6% vs. 0.1%, 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). Conclusion PDM was an independent risk factor for prolonged operative time and anastomotic failure in SRC surgery. Preoperative radiological evaluation using MRP and MIP can help surgeons better handle this rare congenital variant.

Background Laparoscopic total mesorectal excision (LaTME) is technically challenging for ultralow-lying rectal cancer in obese male patients. Herein, we introduced modified serial techniques “ASTRO” to facilitate LaTME, and the short-term outcomes were presented. Methods A prospective study (NCT05067413) was conducted between December 2020 and January 2022. The modified serial surgical techniques “ASTRO” included 5 key steps: 1) Anterior peritoneal reflection (APR) dissection at the highest line along with a "n"-shaped membrane bridge; 2) Suspending the APR with a purse-string suture through the bladder peritoneum to enlarge the operating space of the anterior rectal wall; 3) Traction and counter-traction continuously of the rectum applied with a cotton tape around the rectum; 4) Resection of the pelvic rectum on tripartition, followed by the sequence of "posterior > anterior > lateral" principle; 5) the trans-anterior Obturator nerve gateway was adapted to transect the distal rectum. The operative data and postoperative short-term outcomes were collected. Results 24 consecutive patients underwent this procedure successfully. The average body mass index (BMI) was 29.9 ± 1.3. The average of tumor height from anal verge was 4.0 cm (range, 3.0–4.5 cm). The median operating time and blood loss was 217 min (range,165–420 min) and 50ml (range,20–100 ml) respectively. The anterior operation space at the midsagittal plane of the pelvis inlet was increased by 2.0 ± 0.3 cm. The calculated dominant angle was 20 ± 3°. The length of stapling line was 6.8 ± 1.0 cm with 11 cases by one cartridge and 13 cases by 2 cartridges. 8 patients developed postoperative complications including 4 with anastomosis leakage (16.7%), 2 with urinary retention (8.3%), one with anastomotic stenosis (4.2%) and one with ileus (4.2%). All the complications were relatively mild and recovered well. Conclusion Modified Serial Techniques “ASTRO” could expand the operating space and facilitate LaTME in obese male patients, thereby reducing the risk of conversion to open and transanal dissection.