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Abstract 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

A persistent descending mesocolon is defined as a congenital fixation anomaly caused by the defective membrane fusion of the descending colon and the lateral abdominal wall. Anatomically, in persistent descending mesocolon, the left colonic artery is often shortened, and joins the marginal artery soon after its bifurcation from the inferior mesenteric artery, while the colonic mesentery often adheres firmly to the mesentery of the small intestine. As a result of these characteristics, anatomical knowledge of the persistent descending mesocolon and preservation of bowel blood flow are important during surgery for left-sided colorectal cancer to avoid adverse events. Moreover, indocyanine green based blood flow assessment is useful for the detailed evaluation of bowel ischemia at the anastomotic site. Here we report the usefulness of blood flow evaluation using indocyanine green fluorescence in laparoscopic or robot-assisted surgery for three patients with colorectal cancer and persistent descending mesocolons. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract Background Persistent descending mesocolon, an anomaly of fixation of the mesentery of the descending colon, can sometimes cause complications such as intestinal obstruction and intussusception. We present the first reported case of sigmoid volvulus with persistent descending mesocolon. Case presentation An 82-year-old Japanese man had intermittent lower abdominal pain. Abdominal computed tomography showed dilation and a shift to the right side of the sigmoid colon, but no findings of volvulus. The next day, he presented continuous lower abdominal pain with bloody stool. A second abdominal computed tomography showed strangulation and dilation of the sigmoid colon, with shift from the right side of the abdominal cavity to the pelvic space. This suggested the descending colon was running to the medial side with sigmoid volvulus. Emergency surgery was performed for volvulus with persistent descending mesocolon. Operative findings revealed dilation of the sigmoid colon with a partial poorly colored region and strangulation that caused volvulus. After releasing the strangulation of the sigmoid colon, the descending colon was revealed to be running more to the medial side, with adherence to small intestinal mesentery. There was no Toldt’s fusion fascia at the descending colon. Persistent descending mesocolon was therefore diagnosed due to abnormality of fixation of the descending colon. The sigmoid colon, including the poorly colored region, was resected and reconstructed, while the inferior mesenteric and left colonic arteries were preserved because of the complexity of the vascular system running around the descending and sigmoid colon due to the shortened mesentery. These findings were pathologically compatible with circulatory compromise and intestinal degeneration due to sigmoid volvulus. The patient had no complications after discharge, including in relation to defecation. Conclusion Persistent descending mesocolon can occasionally cause acute abdominal symptoms requiring immediate treatment. A computed tomography finding of the descending colon running more to the medial side than ordinary cases can aid diagnosis of persistent descending mesocolon.

Background: Persistent descending mesocolon, an anomaly of fixation of the mesentery of the descending colon, can sometimes cause complications such as intestinal obstruction and intussusception. We present the first reported case of sigmoid volvulus with persistent descending mesocolon.Case Presentation: An 82-year-old Japanese man had intermittent lower abdominal pain. Abdominal computed tomography showed dilation and a shift to the right side of the sigmoid colon, but no findings of volvulus. The next day, he presented continuous lower abdominal pain with bloody stool. A second abdominal computed tomography showed strangulation and dilation of the sigmoid colon, with shift from the right side of the abdominal cavity to the pelvic space. This suggested the descending colon was running to the medial side with sigmoid volvulus. Emergency surgery was performed for volvulus with persistent descending mesocolon. Operative findings revealed dilation of the sigmoid colon with a partial poorly colored region and strangulation that caused volvulus. After releasing the strangulation of the sigmoid colon, the descending colon was revealed to be running more to the medial side, with adherence to small intestinal mesentery. There was no Toldt's fusion fascia at the descending colon. Persistent descending mesocolon was therefore diagnosed due to abnormality of fixation of the descending colon. The sigmoid colon, including the poorly colored region, was resected and reconstructed, while the inferior mesenteric and left colonic arteries were preserved because of the complexity of the vascular system running around the descending and sigmoid colon due to the shortened mesentery. These findings were pathologically compatible with circulatory compromise and intestinal degeneration due to sigmoid volvulus. The patient had no complications after discharge, including in relation to defecation.Conclusion: Persistent descending mesocolon can occasionally cause acute abdominal symptoms requiring immediate treatment. A computed tomography finding of the descending colon running more to the medial side than ordinary cases can aid diagnosis of persistent descending mesocolon. [ABSTRACT FROM AUTHOR]

Background: Persistent descending mesocolon (PDM) is a fetal abnormality in which the left‐sided colon is not fused to the retroperitoneum, and it is often accompanied by the adhesion between the mesocolon and small bowel mesentery. Due to its rarity, whether PDM exhibits anatomical characteristics of the inferior mesenteric artery (IMA) and left colic artery (LCA), and how the anomaly affects laparoscopic surgery are largely unknown. We investigated the branches of these arteries and outcomes of patients who underwent laparoscopic surgery. Methods: Based on computed tomography (CT) and three‐dimensional CT angiography, branching patterns of the IMA, LCA and branches originating from the LCA were analysed in 954 patients with left‐sided colon or rectal cancer. PDM was diagnosed by preoperative CT colonography, and confirmed at time of surgery. The anatomical features of the vessels and short‐term outcomes of laparoscopic surgery were compared between patient groups stratified by PDM. Results: Twelve patients (1.3%) were diagnosed with PDM. No branching pattern of the IMA specific to PDM was noted. On the other hand, patients with PDM had fewer branches (mean: 1.0) from the LCA than those without PDM (mean: 1.8, p = 0.009). In patients undergoing laparoscopic surgery, outcomes such as operative time, intraoperative blood loss, and number of harvested nodes were comparable between the two patient groups. Conclusion: Few branches of the LCA characterize PDM. PDM does not complicate laparoscopic surgery of the left‐sided colon and rectum. However, the above anatomical feature increases the risk of poor colonic perfusion when dividing the LCA. [ABSTRACT FROM AUTHOR]

Introduction: Persistent descending mesocolon (PDM) represents a failure of fusion of the descending mesentery, leading to anatomical abnormalities. This study aimed to examine the effects of anatomical features of PDM on laparoscopic surgical outcomes. Methods: Patient backgrounds, surgical outcomes, anatomical characteristics, and operative findings were retrospectively compared between 186 patients classified into PDM and non‐PDM groups who underwent primary resection for left‐sided colon and rectal cancer at our hospital from January 2019 to December 2020. Results: PDM was diagnosed in nine patients (4.8%). The operative time (337 ± 165 vs 239 ± 107 min, p = 0.010) was significantly different between PDM and non‐PDM groups, but bleeding loss was not different (108 ± 97 ml vs 53 ± 142 ml, p = 0.259). In PDM patients, in addition to abnormal fixation of the sigmoid‐descending colon junction, adhesion of the mesentery of the colon and small intestine in 100%, and adhesion between the mesocolon in 33% patients was confirmed intraoperatively. Ileus was more common in the PDM group (two cases, 22%) and in the non‐PDM group (10 cases, 5.6%), but there was no significant difference in overall postoperative complications between the two groups (p = 0.215). The duration of postoperative hospital stay (28 ± 20 vs 16 ± 11 days, p = 0.002) was significant between the two groups. The left colonic artery (LCA) could not be preserved in six patients in the PDM group, one of whom had anastomotic leakage and two of whom required additional resections due to intraoperative intestinal blood flow failure. Conclusion: PDM prolonged operative times and duration of postoperative stay in laparoscopic surgery for left‐sided colon and rectal cancer. Division of the LCA in PDM patients should be considered an intraoperative risk factor for injury to the marginal artery. [ABSTRACT FROM AUTHOR]

Abstract Background Persistent descending mesocolon (PDM) is a congenital anomaly associated with the failure of fixation of the descending colon to the lateral abdominal wall. In the laparoscopic colectomy for colorectal cancer, it has been noticed that there are extensive adhesions and a distinctive anatomy of colonic vessels in cases with PDM. Therefore, it is necessary to have sufficient knowledge about PDM so that it can be appropriately treated during surgery. Case presentation Case 1—a 79-year-old man underwent laparoscopic intersphincteric resection for rectal cancer. Preoperative barium enema (BE) revealed that the sigmoid colon was located at the right side of the abdomen. An enhanced computed tomography (CT) showed that the common trunk of the left colic artery (LCA) and the first sigmoid colonic artery (S1) branched from the inferior mesenteric artery (IMA). Case 2—a 68-year-old man underwent laparoscopic sigmoidectomy for sigmoid colon cancer and laparoscopic distal gastrectomy for gastric cancer synchronously. BE showed that the descending colon ran from the splenic flexure to medial caudal side. An enhanced CT showed that the distance from the LCA to the marginal artery was 1.0 cm. Case 3—a 68-year-old man underwent laparoscopic low anterior resection for rectal cancer. BE showed that the descending colon ran to the medial caudal side. An enhanced CT showed that the mesentery of the descending colon was comparatively shortened. Case 4—a 60-year-old man underwent laparoscopic sigmoidectomy for sigmoid colon cancer. An enhanced CT showed that the descending colon ran to the medial caudal side and predicted that the LCA and S1 formed a common trunk and branched radially from the IMA. We reported four cases with PDM recognized preoperatively as above. Three cases had a shortening of the mesocolon. While dissecting the vessels, although special attention was required to maintain the blood flow to the intestine, none of these cases developed any complications during the postoperative course. Conclusions We considered that it is important to have positional awareness of the LCA and the marginal artery to perform the laparoscopic surgery safely when a colorectal cancer with PDM is diagnosed preoperatively using imaging methods.

Abstract Background Persistent descending mesocolon (PDM) is caused by the absence of fusion of the descending colon to the retroperitoneum. We herein report two colorectal cancer cases with PDM that were treated with laparoscopic surgery. Case presentation Case 1: a 50-year-old man with sigmoid colon cancer and synchronous liver metastasis. After neoadjuvant chemotherapy, he underwent laparoscopic sigmoidectomy with lymph node dissection cutting the root of the inferior mesenteric artery (IMA) and synchronous liver resection. He experienced postoperative stenosis of the reconstructed colon possibly due to an impaired arterial blood flow in the reconstructed colon. Case 2: a 77-year-old man with rectal cancer. Laparoscopic low anterior resection preserving the left colic artery (LCA) was performed. Intraoperative infrared ray (IR) imaging using indocyanine green (ICG) showed good blood flow of the reconstructed colon. He had no postoperative complications. In cases of PDM, the mesentery of the descending and sigmoid colon containing the LCA is often shortened, and the marginal artery of the reconstructed colon is located close to the root of the LCA. Lymph node dissection accompanied by cutting the LCA carries a risk of marginal artery injury. Therefore, we recommend lymph node dissection preserving the LCA in colorectal cancer patients with PDM in order to maintain the blood flow of the reconstructed colon. If the IMA and LCA absolutely need to be cut for complete lymph node dissection, the marginal artery should be clearly identified and preserved. In addition, intraoperative IR imaging is extremely useful for evaluating colonic perfusion and reducing the risk of anastomotic complications. Conclusion In colorectal cancer surgery in patients with PDM, surgeons should be aware of these tips for maintaining the blood flow of the reconstructed colon and thereby avoid postoperative complications caused by an impaired blood flow.

Background: Persistent descending mesocolon (PDM) is typically asymptomatic. However, features such as adhesion and variations in vessel anatomy could affect the surgical techniques for colorectal cancer (CRC). This study aimed to investigate the frequency and radiological features of PDM. Short-term outcomes after conventional laparoscopic surgery (CLS) for CRC with PDM were also investigated to assess the feasibility of CLS and identify strategies for minimally invasive surgery (MIS) in CRC with PDM.Methods: Patients who underwent MIS, including CLS and robot-assisted laparoscopic surgery (RALS), for left-sided CRC between April 2016 and June 2019, were investigated. PDM was defined as the existence of the right border of the descending colon inside the right border of the left kidney based on preoperative computed tomography findings.Results: Radiological findings of 837 patients were examined, and PDM was found in 19 (2.3%) patients. Radiality of the inferior mesenteric artery (IMA) was found in 5 of 19 (26.3%) PDM cases, which was significantly higher than that in non-PDM cases. The median lengths between the IMA and inferior mesenteric vein (IMV) and between the IMV and descending colon in PDM cases were 14.8 mm and 17.2 mm, respectively, which were significantly shorter than those in non-PDM cases. Short-term outcomes were evaluated only in CLS cases since the rate of hybrid surgery among RALS cases differed between non-PDM and PDM cases (0% vs. 44.4%), which would affect the surgical outcomes. The short-term outcomes in 447 CLS cases were similar between PDM and non-PDM cases. The frequency of extracorporeal division of the left colic artery (LCA) and IMV was significantly higher in PDM than in non-PDM cases (70.0% vs. 5.7%).Conclusions: This radiological definition of PDM was feasible. CLS for left-sided CRC with PDM was feasible, and dividing the LCA and IMV extracorporeally would be vital for safe surgery. [ABSTRACT FROM AUTHOR]

Background: Persistent descending mesocolon (PDM) is a rare colonic anatomical variant. However, PDM' s impact on the technical aspects and outcomes of laparoscopic colorectal cancer resection are unclear . Patients and Methods: This retrospective clinical cohort study was conducted at a high-volume cancer center in Japan to evaluate intra- and postoperative outcomes of laparoscopic colorectal cancer surgery in patients with (PDM+) or without (PDM-) PDM over the past 7 years. Results: Between January 2012 and September 2019, 2,775 patients underwent laparoscopic colorectal cancer resection at our center, including 60 (2.1%) cases of PDM. Preoperative detection was achieved in only 5 patients (8.3%), 39 patients were men, and 21 patients were women. The average age was 67 years. Twenty patients had a history of prior abdominal surgery (33.3%), with little or no subsequent adhesions. The average duration of sigmoidectomy in PDM+ patients (n=17; 217.7±14.2 min) was significantly longer than that in PDM-- patients (n=547; 176.2±2.4 min; p=0.003), as was average blood loss (32.3±10.6 ml vs. 16.7±2.8 ml; p=0.03). Likewise, average operative time for high anterior resection in PDM+ patients (n=11; 227.1±20.2 min) was significantly longer than that in PDM-- patients (n=294; 195.6±3.0 min; p=0.048). Rates of postoperative anastomotic leakage and postoperative recurrence did not differ in both groups. In PDM+ patients, retention of left colic artery had no impact on proximal specimen margins or occurrences of anastomotic leakage. Conclusion: PDM prolongs operative times and increases bleeding in laparoscopic colorectal cancer surgery and should be considered a risk factor when encountered. [ABSTRACT FROM AUTHOR]

This case report introduces a rare occurrence of transverse colon volvulus associated with persistent descending mesocolon (PDM), a congenital anomaly characterized by the medial positioning of the descending colon due to a failed fusion with the dorsal abdominal wall. We detail the case of an 18-year-old female, with a medical history of surgically corrected coarctation of the aorta and anal atresia, who presented with recurrent transverse colon volvulus despite having undergone a laparoscopic colopexy three years earlier. Physical examination revealed abdominal distension and metallic colic sounds while imaging studies confirmed the recurrence of the volvulus. Laparoscopic partial resection of the transverse colon was performed, which revealed a medially positioned descending colon due to PDM. Postoperative complications included anastomotic failure, necessitating a second operation. The patient was successfully discharged without further complications after seven days. This case underscores the clinical significance of recognizing PDM, highlighting its potential role in causing transverse colon volvulus and increasing the risk of anastomotic failure. It emphasizes the need for surgeons to remain vigilant regarding this congenital anomaly to mitigate unexpected outcomes such as recurrent volvulus and postoperative complications., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Shibata et al.)

A 55-year-old-man underwent laparoscopic sigmoidectomy for sigmoid colon cancer. Preoperative barium enema showed a slightly medial displacement of the descending colon, and the sigmoid colon was quite long. The operative findings showed that the descending colon was not fused with the retroperitoneum and shifted to the midline and the left colon adhered to the small mesentery and right pelvic wall. Thus, a diagnosis of persistent descending mesocolon (PDM) was made. The left colon, sigmoid colon, and superior rectal arteries often branch radially from the inferior mesenteric artery. The sigmoid mesentery shortens, and the inferior mesenteric vein is often close to the marginal vessels. By understanding the anatomical feature of PDM and devising surgical techniques, laparoscopic sigmoidectomy for sigmoid colon cancer with PDM could be performed without compromising its curative effect and safety. [ABSTRACT FROM AUTHOR]

Introduction Situs inversus viscerum, a congenital condition in which the visceral organs are a mirror image of their normal physiological positions, could be total or partial. Persistent descending mesocolon (PDM) is a congenital anomaly that is asymptomatic because of its short length. PDM causing intestinal obstruction is a known clinical complication. Presentation of case A 74-year-old woman presented with pneumaturia and enteruria for two months, and recurrent cystitis for a month. An enhanced computed tomography (CT) showed air in the bladder along with sigmoid colonic diverticula adherent to it, suspecting a fistula. The CT also showed partial situs inversus with the common hepatic artery, and left colic artery arising abnormally from the superior mesenteric artery (SMA). Minimally invasive endoscopic closure using the over-the-scope clipping system was difficult because of thickening and scar tissue due to chronic inflammation from diverticulitis. Thus, a sigmoidectomy was performed to close the fistula. Intraoperatively, we noted an abnormally fixed descending mesocolon. An emergency reoperation was performed on the sixth postoperative day owing to an anastomotic leak. Suture failure was attributed to these congenital abnormalities due to insufficient blood flow from an absent marginal vessel and a high endocolonic pressure by adhesions. Sigmoid colon re-resection and maturation of an ileostomy was performed. The patient had no specific postoperative complications, and the ileostomy was closed after three months. Conclusion We report an extremely rare case of colovesical fistula due to a PDM in a patient having partial situs inversus with abnormal branches originating from the SMA. [ABSTRACT FROM AUTHOR]

During our practice as clinical surgeons, we have encountered situations in which exploratory abdominal laparotomies have yielded unexpected outcomes, despite conducting thorough and rigorous preoperative studies. A rare condition called sclerosing encapsulating peritonitis (SEP), in which a fibrocollagenous membrane encircles the intestine and other abdominal organs, surprised us in a case of an acute abdomen. Persistent descending mesocolon is another unusual condition in which the descending colon is transferred downward and to the right abdominal region because its mesocolon is unable to merge with the posterior abdominal wall. Those two different conditions are extremely rare and were never been described in a single case. We present a case of an 80-year-old male who presented in the emergency department with an acute abdomen and puzzled us., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Skarmoutsou et al.)

Introduction. Positional anomalies of the right half of the colon are quite common whereas positional anomalies of the left half of the colon are much less common because of embryological disorders during the period of the embryological development of that part of the bowel. The process of the fixation of the descending colon to the posterior abdominal wall can be absent. In that case, when the descending colon has a free descending mesocolon, it shows some degree of mobility. Case Outline. We are presenting an example of one of the anomalies, which is characterized by the persistent descending mesocolon, which extends from the splenic flexure or just below it to the sigmoid colon. The persistent descending mesocolon in our case contains or surrounds almost complete small bowel in a recess which is located laterally to the left of the midline. The content of this hernial sac simulates the symptoms of an internal hernia followed by clinical symptoms and roendgenographical signs. Conclusion. We are of the opinion that this anomaly is more common than some surveys of literature would suggest.

Although rare, persistent descending mesocolon (PDM) is an anatomical anomaly that carries potential risks for laparoscopic colorectal surgery. Impaired blood circulation of the reconstructed colon is especially risky during surgery. We report a case of sigmoid cancer with PDM, in which the patient underwent laparoscopic sigmoidectomy. A 52-year-old man diagnosed with sigmoid cancer was referred to our hospital. PDM was identified with preoperative enhanced-contrast computed tomography, which revealed the sigmoid colon located in the right lower quadrant and a bear-claw inferior mesenteric artery (IMA). Preoperative examination showed cT1N0M0 stage I (Union for International Cancer Control {UICC} eighth). We were not able to identify the branches of IMA after the medial-to-lateral approach. We divided the mesentery and marginal artery and the main branches from IMA extracorporeally prior to lymphadenectomy. Each oral and anal side was dissected without touching the tumor. Then, we marked the line for lymphadenectomy using the dissected line of mesentery as an intracorporeal landmark. Pathological findings showed pT1N0M0 stage I (UICC eighth edition). The patient was discharged without complications. Using this approach and the preoperative recognition of PDM, we performed laparoscopic sigmoidectomy with lymphadenectomy for early-stage PDM case successfully and safely. Our mesocolon dissection-first approach could be a feasible and safer approach for early-stage sigmoid cancer., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2022, Fujiwara et al.)

Persistent descending mesocolon (PDM) is a fixed abnormality in which the descending to sigmoid colon adheres to the small intestinal mesentery or right pelvic wall through right displacement. Surgery for colorectal cancer with PDM is difficult. Therefore, in addition to the anatomical characteristics of PDM, the extent of adhesion and characteristics of vascular courses need to be assessed in individual patients. The number of patients now undergoing laparoscopic or robot-assisted surgery for colorectal cancer has rapidly increased. We herein report a rectal cancer patient with PDM who safely underwent robot-assisted laparoscopic low anterior resection (RLAR). A 71-year-old male was referred to our hospital for a detailed examination following a fecal occult blood-positive reaction. Lower gastrointestinal endoscopy revealed a type 2 lesion of the rectum. Moderately differentiated adenocarcinoma was diagnosed based on the results of a histopathological examination. Preoperative contrast-enhanced thoracoabdominal computed tomography showed abnormalities in the colonic course and characteristic vascular courses, suggesting rectal cancer with PDM. RLAR was performed. In surgery, it is important to initially perform adhesiolysis accurately in order to reconstruct the original shape of the colonic mesentery and confirm/dissect vascular bifurcations due to the risk of marginal arterial injury. In the present case, a detailed anatomical understanding of the site of intestinal adhesion and vascular courses, as well as surgical procedures, facilitated safe RLAR. We described this case and reviewed the anatomical characteristics of PDM and cautions for surgery. • The descending colon is not fused to the retroperitoneum in persistent descending mesocolon. • In colorectal cancer with persistent descending mesocolon, surgery is difficult. • Adhesiolysis is performed for original colonic mesentery shape recovery. • Due to the risk of marginal artery injury, vascular bifurcations are dissected. • Robot-assisted laparoscopic low anterior resection is safe for rectal cancer with persistent descending mesocolon. [ABSTRACT FROM AUTHOR]

Background: Persistent descending mesocolon (PDM) is a congenital anomaly associated with the failure of fixation of the descending colon to the lateral abdominal wall. In the laparoscopic colectomy for colorectal cancer, it has been noticed that there are extensive adhesions and a distinctive anatomy of colonic vessels in cases with PDM. Therefore, it is necessary to have sufficient knowledge about PDM so that it can be appropriately treated during surgery. Case presentation: Case 1—a 79-year-old man underwent laparoscopic intersphincteric resection for rectal cancer. Preoperative barium enema (BE) revealed that the sigmoid colon was located at the right side of the abdomen. An enhanced computed tomography (CT) showed that the common trunk of the left colic artery (LCA) and the first sigmoid colonic artery (S1) branched from the inferior mesenteric artery (IMA). Case 2—a 68-year-old man underwent laparoscopic sigmoidectomy for sigmoid colon cancer and laparoscopic distal gastrectomy for gastric cancer synchronously. BE showed that the descending colon ran from the splenic flexure to medial caudal side. An enhanced CT showed that the distance from the LCA to the marginal artery was 1.0 cm. Case 3—a 68-year-old man underwent laparoscopic low anterior resection for rectal cancer. BE showed that the descending colon ran to the medial caudal side. An enhanced CT showed that the mesentery of the descending colon was comparatively shortened. Case 4—a 60-year-old man underwent laparoscopic sigmoidectomy for sigmoid colon cancer. An enhanced CT showed that the descending colon ran to the medial caudal side and predicted that the LCA and S1 formed a common trunk and branched radially from the IMA. We reported four cases with PDM recognized preoperatively as above. Three cases had a shortening of the mesocolon. While dissecting the vessels, although special attention was required to maintain the blood flow to the intestine, none of these cases developed any complications during the postoperative course. Conclusions: We considered that it is important to have positional awareness of the LCA and the marginal artery to perform the laparoscopic surgery safely when a colorectal cancer with PDM is diagnosed preoperatively using imaging methods. [ABSTRACT FROM AUTHOR]

Background: Persistent descending mesocolon (PDM) is a rare colonic anatomical variant. However, PDM's impact on the technical aspects and outcomes of laparoscopic colorectal cancer resection are unclear., Patients and Methods: This retrospective clinical cohort study was conducted at a high-volume cancer center in Japan to evaluate intra- and postoperative outcomes of laparoscopic colorectal cancer surgery in patients with (PDM+) or without (PDM-) PDM over the past 7 years., Results: Between January 2012 and September 2019, 2,775 patients underwent laparoscopic colorectal cancer resection at our center, including 60 (2.1%) cases of PDM. Preoperative detection was achieved in only 5 patients (8.3%), 39 patients were men, and 21 patients were women. The average age was 67 years. Twenty patients had a history of prior abdominal surgery (33.3%), with little or no subsequent adhesions. The average duration of sigmoidectomy in PDM+ patients (n=17; 217.7±14.2 min) was significantly longer than that in PDM- patients (n=547; 176.2±2.4 min; p=0.003), as was average blood loss (32.3±10.6 ml vs. 16.7±2.8 ml; p=0.03). Likewise, average operative time for high anterior resection in PDM+ patients (n=11; 227.1±20.2 min) was significantly longer than that in PDM- patients (n=294; 195.6±3.0 min; p=0.048). Rates of postoperative anastomotic leakage and postoperative recurrence did not differ in both groups. In PDM+ patients, retention of left colic artery had no impact on proximal specimen margins or occurrences of anastomotic leakage., Conclusion: PDM prolongs operative times and increases bleeding in laparoscopic colorectal cancer surgery and should be considered a risk factor when encountered., (Copyright© 2020, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Background: Persistent descending mesocolon (PDM) is caused by the absence of fusion of the descending colon to the retroperitoneum. We herein report two colorectal cancer cases with PDM that were treated with laparoscopic surgery. Case presentation: Case 1: a 50-year-old man with sigmoid colon cancer and synchronous liver metastasis. After neoadjuvant chemotherapy, he underwent laparoscopic sigmoidectomy with lymph node dissection cutting the root of the inferior mesenteric artery (IMA) and synchronous liver resection. He experienced postoperative stenosis of the reconstructed colon possibly due to an impaired arterial blood flow in the reconstructed colon. Case 2: a 77-year-old man with rectal cancer. Laparoscopic low anterior resection preserving the left colic artery (LCA) was performed. Intraoperative infrared ray (IR) imaging using indocyanine green (ICG) showed good blood flow of the reconstructed colon. He had no postoperative complications. In cases of PDM, the mesentery of the descending and sigmoid colon containing the LCA is often shortened, and the marginal artery of the reconstructed colon is located close to the root of the LCA. Lymph node dissection accompanied by cutting the LCA carries a risk of marginal artery injury. Therefore, we recommend lymph node dissection preserving the LCA in colorectal cancer patients with PDM in order to maintain the blood flow of the reconstructed colon. If the IMA and LCA absolutely need to be cut for complete lymph node dissection, the marginal artery should be clearly identified and preserved. In addition, intraoperative IR imaging is extremely useful for evaluating colonic perfusion and reducing the risk of anastomotic complications. Conclusion: In colorectal cancer surgery in patients with PDM, surgeons should be aware of these tips for maintaining the blood flow of the reconstructed colon and thereby avoid postoperative complications caused by an impaired blood flow. [ABSTRACT FROM AUTHOR]

Persistent ascending or descending mesocolon is an embryological anomaly that occurs during the final process of intestinal development in organogenesis. Specifically, the primitive dorsal mesocolon fails to fuse with the parietal peritoneum in the fifth month of gestation. Herein, we describe a case of ascending colon cancer with persistent ascending and descending mesocolon treated by laparoscopic right hemicolectomy. Preoperative computed tomography imaging of the abdomen demonstrated that the descending colon shifted at the midline of the abdomen and the sigmoid colon was located under the ascending colon. The detailed preoperative imaging examination revealed malpositioning of the large intestine and aided in the procedural planning. Because persistent mesocolon may result in the formation of abnormal adhesions, an accurate preoperative diagnosis is essential. We propose that it is important to consider this anomaly when making the preoperative imaging diagnosis to ensure a safe operation.