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.

OBJECTIVE: Persistent descending mesocolon (PDM) increases the difficulty and colonic ischemia in the surgery of colorectal cancer, but the preoperative diagnostic criteria have not yet been clearly demonstrated. This study explored the MR imaging features and diagnostic criteria of PDM to improve the preoperative diagnostic rate.
METHODS: The clinical data of 54 patients with PDM and 270 patients without PDM who underwent rectal surgery at the Department of Colorectal Surgery, Fujian Medical University Union Hospital, from March 2018 to December 2022 were analyzed, retrospectively. The radiological parameters of PDM from MRI were analyzed.
RESULTS: On MRI T2WI axial image, the left edge of the abdominal aorta was defined as the reference line. The shortest vertical distance between the right edge of the descending colon and this line (dN) and the maximum transverse diameter of the peritoneal cavity (dA) at the same level and the maximum vertical distance between the right edge of the descending colon and this line (dW) were measured. There were significant statistical differences in dN, dW, dN/dW, and dN/dA between the PDM group and the non-PDM group. dN, dN/dW, and dN/dA have high diagnostic performance for the PDM. dN < 4.16 cm, dN/dW < 0.52, and dN/dA < 0.15 can all be used as clues to diagnose PDM.
CONCLUSIONS: We propose a feasible set of diagnostic criteria for PDM based on abdominal MRI, which can quickly and accurately diagnose PDM, and provide some reference for preoperative planning and surgical decision-making.

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.

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.

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.
METHODS: 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).
CONCLUSIONS: 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.

BACKGROUND: 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.
CONCLUSIONS: 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.

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.
METHODS: 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.
CONCLUSIONS: 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.

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.

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.
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.
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.
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.

BACKGROUND: 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).
METHODS: 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.
CONCLUSIONS: 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.
CONCLUSIONS: 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.