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Objective: To identify if there is an association between pelvic entry and pelvic outlet diameters with increased positive circumferential resection margin (CRM) in rectal cancer. Introduction: Positive CRMin rectalcancerisa majorpredictor forlocal anddistant recurrence. Pelvic diameters may be related to the difficulty of dissection, as well as intrinsic tumor characteristics such as tumor size, location, distance from the anal margin, and T stage, which may compromise the integrity of the mesorectum and circumferential margin involvement. Methods: A retrospective review of the patient's medical records who underwent surgical resection of rectal adenocarcinoma from January 2012 to June 2022 was performed. The patient's preoperative staging, operative characteristics, and histopathologic outcomes were gathered from the medical records. Preoperative MRI scanning was done in all patients. MRI pelvimetry was done by two observers. CRM involvement was recorded as stated in the pathology report. Pelvimetry variables were dichotomized according to their mean values for correlation analysis. The odds ratio (OR) was calculated from a binary logistics regression model to assess the relation between the positive CRM and the independent variables. Results: A total of 78 patients were included in this study. A positive CRM was reported in 10 patients (12.8%). BMI >27.4 + 6.6 (p = 0.02), positive extramural vascular invasion (p = 0.027), positive CRM by MRI scanning (p = 0.004), and anal sphincter involvement (p = 0.03) were associated with positive CRM. Pelvimetry values were not associated with a positive CRM. Conclusion: No association was found between the pelvic diameters measured by MRI pelvimetry with a positive CRM. (AU)

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Los tumores de la fosa isquiorrectal son poco frecuentes, habitualmente descritos en reportes o series de casos. Estas lesiones son un reto terapéutico, requiriendo un estudio preoperatorio apropiado, además de discusión y manejo guiado por un comité multidisciplinario, que permiten lograr resultados óptimos tanto oncológicos como funcionales. Presentamos un caso de un hombre de 73 años con antecedentes de resección de un tumor glúteo izquierdo en otro centro 5 años antes. La biopsia fue compatible con un sarcoma epiteloideo (SE) de alto grado, con margen quirúrgico < 0,5 mm que requirió ampliación de los márgenes posteriormente. Además, se realizó radioterapia adyuvante. Al cuarto año de seguimiento el paciente desarrolla dolor e induración con retracción en relación a cicatriz quirúrgica, siendo objetivada una recidiva tumoral local. Luego de una discusión multidisciplinaria, se realizó una desfuncionalización con ileostomía en asa laparoscópica y resección tumoral con preservación del ano y del piso pélvico. El defecto fue cubierto por el equipo de cirugía plástica utilizando un colgajo perforante de la arteria glútea superior. La biopsia confirmó la recidiva tumoral y los márgenes quirúrgicos fueron negativos. El paciente es dado de alta a los 25 días postoperatorios por cuidados del colgajo, sin complicaciones. Al año de seguimiento el paciente no presenta recidiva tumoral, la ileostomía fue cerrada, y sus resultados funcionales en términos defecatorios y de la herida son buenos.

Ischiorectal fossa tumors are rare lesions, mostly described in case reports or case series. These lesions represent a diagnostic and therapeutic challenge. Hence, an appropriate preoperative study and multidisciplinary discussion are essential to achieve good oncologic and functional results. We report a case of a 73-year-old male operated on five years before in another health center due to the diagnosis of a left gluteal tumor. The lesion was excised, and biopsies confirmed a high-grade epithelioid sarcoma with a close margin, requiring a subsequent wider excision of the surgical margins. The patient received adjuvant radiotherapy. After four years of follow-up, the patient developed mild pain with skin retraction around the former incision. A local recurrence was diagnosed by imaging. In a multidisciplinary team meeting, a decision to resect the lesion with preservation of the anus and the pelvic floor was taken. The patient underwent a laparoscopic defunctioning loop ileostomy and a resection of the recurrent tumor in the ischiorectal fossa with preservation of the anal sphincter. The defect was covered utilizing a superior gluteal artery perforator flap and a partial gluteus maximus muscle rotation. The tumor was completely excised with negative margins. The patient was discharged without complications after 25 days due to flap management. After one year of follow-up, the patient is recurrence-free, and the ileostomy was closed.

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Objective: To investigate the causes and management of long-term persistent pelvic presacral space infection. Methods: Clinical data of 10 patients with persistent presacral infection admitted to the Cancer Hospital of Zhengzhou University from October 2015 to October 2020 were collected. Different surgical approaches were used to treat the presacral infection according to the patients' initial surgical procedures. Results: Among the 10 patients, there were 2 cases of presacral recurrent infection due to rectal leak after radiotherapy for cervical cancer, 3 cases of presacral recurrent infection due to rectal leak after radiotherapy for rectal cancer Dixons, and 5 cases of presacral recurrent infection of sinus tract after adjuvant radiotherapy for rectal cancer Miles. Of the 5 patients with leaky bowel, 4 had complete resection of the ruptured nonfunctional bowel and complete debridement of the presacral infection using an anterior transverse sacral incision with a large tipped omentum filling the presacral space; 1 had continuous drainage of the anal canal and complete debridement of the presacral infection using an anterior transverse sacral incision. 5 post-Miles patients all had debridement of the presacral infection using an anterior transverse sacral incision combined with an abdominal incision. The nine patients with healed presacral infection recovered from surgery in 26 to 210 days, with a median time of 55 days. Conclusions: Anterior sacral infections in patients with leaky gut are caused by residual bowel secretion of intestinal fluid into the anterior sacral space, and in post-Miles patients by residual anterior sacral foreign bodies. An anterior sacral caudal transverse arc incision combined with an abdominal incision is an effective surgical approach for complete debridement of anterior sacral recalcitrant infections.

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Pelvic exenteration is often required for primary rectal cancer beyond total mesorectal excision (PRC-bTME) and locally recurrent rectal cancer (LRRC). Some patients with radical resection can achieve long-term survival, but they need to face risks, such as huge surgical trauma, serious perioperative complications, permanent loss of organ function and decline in quality of life. Preoperative evaluation of PRC-bTME and LRRC should emphasize multidisciplinary collaboration, and develop individualized diagnosis and treatment strategies. The principles of function preservation and risk-benefit balance in surgery oncology should be followed, and R0 resection should be emphasized. Perioperative complications, surgical trauma and organ function loss should be minimized to achieve the best quality control and balance point. This consensus was formulated by the Colorectal Cancer Committee of the Chinese Medical Doctor Association and the Gastrointestinal Surgery Committee of China International Exchange and Promotive Association for Medical and Health Care. The draft was formed based on the summary of domestic and foreign research progress and expert experience. After discussion, review and modification by experts, an anonymous voting was conducted for each major opinion, and in-depth verification was carried out according to the principles of evidence-based medicine. Finally, the Chinese expert consensus on the pelvic exenteration with primary rectal cancer beyond total mesorectal excision planes and locally recurrent rectal cancer (2023 edition) was formed. This consensus mainly summarizes the indications and contraindications of PE for PRC-bTME and LRRC, preoperative diagnosis and evaluation, perioperative treatment, as well as the resection scope, surgical methods, reconstruction of related organs, safety and complications of PE, postoperative follow-up and other issues, in order to provide guidance for PE in patients with PRC-bTME and LRRC.

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After the implementation of neoadjuvant chemoradiotherapy and total mesorectal excision, lateral local recurrence becomes the major type of local recurrence after surgery in rectal cancer. Most lateral recurrence develops from enlarged lateral lymph nodes on an initial imaging study. Evidence is accumulating to support the combined use of neoadjuvant chemoradiotherapy and lateral lymph node dissection. The accuracy of diagnosing lateral lymph node metastasis remains poor. The size of lateral lymph nodes is still the most commonly used variable with the most consistent accuracy and the cut-off value ranging from 5 to 8 mm on short axis. The morphological features, differentiation of the primary tumor, circumferential margin, extramural venous invasion, and response to chemoradiotherapy are among other risk factors to predict lateral lymph node metastasis. Planning multiple disciplinary treatment strategies for patients with suspected nodes must consider both the risk of local recurrence and distant metastasis. Total neoadjuvant chemoradiotherapy is the most promising regimen for patients with a high risk of recurrence. Simultaneous Integrated Boost Intensity-Modulated Radiation Therapy seemingly improves the local control of positive lateral nodes. However, its impact on the safety of surgery in patients with no response to the treatment or regrowth of lateral nodes remains unclear. For patients with smaller nodes below the cut-off value or shrunken nodes after treatment, a close follow-up strategy must be performed to detect the recurrence early and perform a salvage surgery. For patients with stratified lateral lymph node metastasis risks, plans containing different multiple disciplinary treatments must be carefully designed for long-term survival and better quality of life.

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Colorectal cancer is one of the most common cancers in the world, and surgery is the mainstage treatment. Urogenital and sexual dysfunction after radical resection of rectal cancer has become an important problem for patients, which seriously affects the quality of life. Some patients give up radical surgery for rectal cancer because of the concerns about sexual and urinary dysfunction. The cause of this problem is intraoperative of injury pelvic autonomic nerve. The preservation of the hypogastric nerve during the surgery is important for the male ejaculation. Pelvic splanchnic nerves are mainly responsible for the male erection. The anatomical origin, distribution, and urogenital function of these two nerves are detailed described in this article. At the same time, this article introduces the classification, key points of the operation and the evaluation of autonomic nerve preservation surgery. With the rapid development of minimally invasive surgery, performing radical surgery for rectal cancer is important, we also need to fully understand the anatomical concept of pelvic autonomic nerves, and apply modern minimally invasive surgical techniques to preserve the patient's pelvic autonomic nerves as well. It is an compulsory course and an important manifestation for the standardization of rectal cancer surgery.

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Objective: To investigate the factors influencing tumor-specific survival of early-onset locally advanced rectal cancer. Methods: All-age patients with primary locally advanced rectal cancer from the Surveillance, Epidemiology, and End Results (SEER) database (2010 to 2019) were included in this study. Early- and late-onset locally advanced rectal cancer was defined according to age of 50 years at diagnosis. Early-onset locally advanced rectal cancer was divided into five age groups for subgroup analyses. Age, sex, tumor-specific survival time and survival status of patients at diagnosis, pathological grade, TNM stage, perineural invasion, tumor deposits, tumor size, pretreatment CEA , radiotherapy, chemotherapy, and number of lymph node dissections were included. Progression-free survival (PFS) was analyzed and compared between patients with early- and late-onset rectal cancer. Results: A total of 5,048 patients with locally advanced rectal cancer were included in the study (aged 27-70 years): 1,290 (25.55%) patients with early-onset rectal cancer and 3,758 (74.45%) patients with late-onset rectal cancer. Patients with early-onset rectal cancer had a higher rate of perineural invasion (P<0.001), more positive lymph nodes dissected (P<0.001), higher positive lymph node ratios (P<0.001), and a higher proportion receiving preoperative radiotherapy (P=0.002). Patients with early-onset rectal cancer had slightly better short-term survival than those with late-onset rectal cancer (median (IQR ): 54 (33-83) vs 50 (31-79) months, χ2=5.192, P=0.023). Multivariate Cox regression for all patients with locally advanced rectal cancer showed that age (P=0.008), grade of tumor differentiation (P=0.002), pretreatment CEA (P=0.008), perineural invasion (P=0.021), positive number (P=0.004) and positive ratio (P=0.001) of dissected lymph nodes, and sequence of surgery and radiotherapy (P=0.005) influenced PFS. This suggests that the Cox regression results for all patients may not be applicable to patients with early-onset cancer. Cox analysis showed tumor differentiation grade (patients with low differentiation had a higher risk of death, P=0.027), TNM stage (stage III patients had a higher risk of death, P=0.025), T stage (higher risk of death in stage T4, P<0.001), pretreatment CEA (P=0.002), perineural invasion (P<0.001), tumor deposits (P=0.005), number of dissected lymph nodes (patients with removal of 12-20 lymph nodes had a lower risk of death, P<0.001), and positive number of dissected lymph nodes (P<0.001) were independent factors influencing PFS of patients with early-onset locally advanced rectal cancer. Conclusion: Patients with early-onset locally advanced rectal cancer were more likely to have adverse prognostic factors, but an adequate number of lymph node dissections (12-20) resulted in better survival outcomes.

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In recent years, with advances in pelvic oncology and surgical techniques, surgeons have redefined the boundaries of pelvic surgery. Combined pelvic exenteration is now considered the treatment of choice for some patients with locally advanced and locally recurrent rectal cancer, but it is only performed in a few hospitals in China due to the complexity of the procedure and the large extent of resection, complications, and high perioperative mortality. Although there have been great advances in oncologic drugs and surgical techniques and equipment in recent years, there are still many controversies and challenges in the preoperative assessment of combined pelvic organ resection, neoadjuvant treatment selection and perioperative treatment strategies. Adequate understanding of the anatomical features of the pelvic organs, close collaboration of the clinical multidisciplinary team, objective assessment and standardized preoperative combination therapy creates the conditions for radical surgical resection of recurrent and complex locally advanced rectal cancer, while the need for rational and standardized R0 resection still has the potential to bring new hope to patients with locally advanced and recurrent rectal cancer.

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The China PelvEx Collaborative, under the direction of Colorectal Cancer Committee of the Chinese Medical Doctor Association, Gastrointestinal Surgery Committee of China International Exchange and Promotive Association for Medical and Health, has formulated and issued the Chinese expert consensus for primary rectal cancer beyond total mesorectal excision planes and locally recurrent rectal cancer (2023 edition) , with the academic support of the Chinese Journal of Gastrointestinal Surgery and Chinese Journal of Colorectal Disease (Electronic Edition). This Consensus refers to the expert consensus developed by the International PelvEx Collaboration, incorporates the latest international multi-center research results and combines the latest research results in China. The Consensus unifies some definitions, clarifies the surgical indications, and puts forward the definition and preventive measures of "empty pelvic syndrome" earlier. For the controversial classification of local recurrent rectal cancer, the Chinese classification was proposed for the first time in Consensus. At the same time, the definition of pelvic exenteration is controversial, and a more consistent cognition is proposed. It is believed that, with the in-depth research on complicated rectal cancer, C-PelvEx will gather more higher-level data from clinical research in several domestic centers, so as to further enrich the content of the updated Consensus.

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Objective: To explore the feasibility, safety, and short- and long-term efficacy of laparoscopic pelvic exenteration (LPE) in treating locally advanced rectal cancer. Methods: The clinical data of 173 patients who had undergone pelvic exenteration (PE) for locally advanced rectal cancer that had been shown by preoperative imaging or intraoperative exploration to have invaded beyond the mesorectal excision plane and adjacent organs in the Cancer Hospital, Chinese Academy of Medical Sciences (n=64) and Peking University First Hospital (n=109) from 2010 January to 2021 December were collected retrospectively. Laparoscopic PE (LPE) had been performed on 82 of these patients and open PE (OPE) on 91. Short- and long-term outcomes (1-, 3-, and 5-year overall and disease-free survival and 1- and 3-year cumulative local recurrence rates) were compared between these groups. Results: The only statistically significant difference in baseline data between the two groups (P>0.05) was administration of neoadjuvant therapy. Compared with OPE, LPE had a significantly shorter operative time (319.3±129.3 minutes versus 417.3±155.0 minutes, t=4.531, P<0.001) and less intraoperative blood loss (175 [20-2000] ml vs. 500 [20-4500] ml, U=2206.500, P<0.001). The R0 resection rates were 98.8% and 94.5%, respectively (χ2=2.355, P=0.214). At 18.3% (15/82), and the incidence of perioperative complications was lower in the LPE group than in the OPE group (37.4% [34/91], χ2=7.727, P=0.005). The rates of surgical site infection were 7.3% (6/82) and 23.1% (21/91) in the LPE and OPE group, respectively (χ2=8.134, P=0.004). The rates of abdominal wound infection were 0 and 12.1% (11/91) (χ2=10.585, P=0.001), respectively, and of urinary tract infection 0 and 6.6% (6/91) (χ2=5.601, P=0.030), respectively. Postoperative hospital stay was shorter in the LPE than OPE group (12 [4-60] days vs. 15 [7-87] days, U=2498.000, P<0.001). The median follow-up time was 40 (2-88) months in the LPE group and 59 (1-130) months in the OPE group. The 1-, 3-, and 5-year overall survival rates were 91.3%, 76.0%, and 62.5%, respectively, in the LPE group, and 91.2%, 68.9%, and 57.6%, respectively, in the OPE group. The 1, 3, and 5-year disease-free survival rates were 82.8%, 64.9%, and 59.7%, respectively, in the LPE group and 76.9%, 57.8%, and 52.7%, respectively, in the OPE group. The 1- and 3-year cumulative local recurrence rates were 5.1% and 14.1%, respectively, in the LPE group and 8.0% and 15.1%, respectively, in the OPE group (both P>0.05). Conclusions: In locally advanced rectal cancer patients, LPE is associated with shorter operative time, less intraoperative blood loss, fewer perioperative complications, and shorter hospital stay compared with OPE. It is safe and feasible without compromising oncological effect.

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Objective: To investigate the value of reconstruction of pelvic floor with biological products to prevent and treat empty pelvic syndrome after pelvic exenteration (PE) for locally advanced or recurrent rectal cancer. Methods: This was a descriptive study of data of 56 patients with locally advanced or locally recurrent rectal cancer without or with limited extra-pelvic metastases who had undergone PE and pelvic floor reconstruction using basement membrane biologic products to separate the abdominal and pelvic cavities in the Department of Anorectal Surgery of the Second Affiliated Hospital of Naval Military Medical University from November 2021 to May 2022. The extent of surgery was divided into two categories: mainly inside the pelvis (41 patients) and including pelvic wall resection (15 patients). In all procedures, basement membrane biologic products were used to reconstruct the pelvic floor and separate the abdominal and pelvic cavities. The procedures included a transperitoneal approach, in which biologic products were used to cover the retroperitoneal defect and the pelvic entrance from the Treitz ligament to the sacral promontory and sutured to the lateral peritoneum, the peritoneal margin of the retained organs in the anterior pelvis, or the pubic arch and pubic symphysis; and a sacrococcygeal approach in which biologic products were used to reconstruct the defect in the pelvic muscle-sacral plane. Variables assessed included patients' baseline information (including sex, age, history of preoperative radiotherapy, recurrence or primary, and extra-pelvic metastases), surgery-related variables (including extent of organ resection, operative time, intraoperative bleeding, and tissue restoration), post-operative recovery (time to recovery of bowel function and time to recovery from empty pelvic syndrome), complications, and findings on follow-up. Postoperative complications were graded using the Clavien-Dindo classification. Results: The median age of the 41 patients whose surgery was mainly inside the pelvis was 57 (31-82) years. The patients comprised 25 men and 16 women. Of these 41 patients, 23 had locally advanced disease and 18 had locally recurrent disease; 32 had a history of chemotherapy/immunotherapy/targeted therapy and 24 of radiation therapy. Among these patients, the median operative time, median intraoperative bleeding, median time to recovery of bowel function, and median time to resolution of empty pelvic syndrome were 440 (240-1020) minutes, 650 (200-4000) ml, 3 (1-9) days, and 14 (5-105) days, respectively. As for postoperative complications, 37 patients had Clavien-Dindo < grade III and four had ≥ grade III complications. One patient died of multiple organ failure 7 days after surgery, two underwent second surgeries because of massive bleeding from their pelvic floor wounds, and one was successfully resuscitated from respiratory failure. In contrast, the median age of the 15 patients whose procedure included combined pelvic and pelvic wall resection was 61 (43-76) years, they comprised eight men and seven women, four had locally advanced disease and 11 had locally recurrent disease. All had a history of chemotherapy/ immunotherapy and 13 had a history of radiation therapy. The median operative time, median intraoperative bleeding, median time to recovery of bowel function, and median time to relief of empty pelvic syndrome were 600 (360-960) minutes, 1600 (400-4000) ml, 3 (2-7) days, and 68 (7-120) days, respectively, in this subgroup of patients. Twelve of these patients had Clavien-Dindo < grade III and three had ≥ grade III postoperative complications. Follow-up was until 31 October 2022 or death; the median follow-up time was 9 (5-12) months. One patient in this group died 3 months after surgery because of rapid tumor progression. The remaining 54 patients have survived to date and no local recurrences have been detected at the surgical site. Conclusion: The use of basement membrane biologic products for pelvic floor reconstruction and separation of the abdominal and pelvic cavities during PE for locally advanced or recurrent rectal cancer is safe, effective, and feasible. It improves the perioperative safety of PE and warrants more implementation.

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Locally advanced tumor with involvement of surrounding tissues and organs is a common situation in pelvic malignancies. Up to 10% of newly diagnosed rectal cancer cases infiltrate to adjacent tissues and organs. Satisfactory resection margins obtained by pelvic exenteration can achieve a 5-year survival rate similar to cases that without adjacent tissue invasion. The 5-year survival rate of patients with locally recurrent pelvic malignancies is almost zero if they are treated only with radiotherapy and chemotherapy. To obtain negative margins through pelvic exenteration is the only chance for a long-term survival of these patients. However, pelvic exenteration is a complicated procedure with higher morbidity and mortality. The development of fascia anatomy enables surgeons to have a deeper understanding and comprehensive application of pelvic fasciae. Meanwhile, the improvement of laparoscopic technology provides a clearer view for surgeons and enables the application of minimally invasive techniques in complex pelvic exenteration. The fascial space priority approach is based on the fascia anatomy of pelvis and giving priority to the separation of the pelvic avascular fascial spaces, which provides a reproducible surgical approach for complex pelvic exenteration.

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ISR is the most widely used anal-preserving operation for ultra-low rectal cancer. It can be divided into total ISR, subtotal ISR and partial ISR according to the resection range of internal sphincter. The advantage of ISR is that it can preserve the sphincter while ensuring the safety of oncology for ultra-low rectal cancer, representing the state of the art. However, it still needs to face the problem that the quality of life will decline due to poor postoperative anal function. The conformal sphincter-preserving operation (CSPO) is a functional anal-preserving surgery improved on the basis of ISR. It is superior to ISR in the postoperative anal function and patients' quality of life. So it can be a new choice for ultra-low rectal cancer.

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The anatomical studies of intersphincteric resection (ISR) have made remarkable progress in recent years. The anatomy of internal, external sphincter and hiatal ligament has been further understood. In this paper, the generation and functional mechanism of ISR related anatomy are described from the embryonic development process, and then the influence of hiatal ligament and internal sphincter on ISR surgery is analyzed respectively according to the anatomical characteristics. Finally, the correlation analysis of anatomical factors on the common problems of mucosal bleeding and instrument anastomosis in ISR is carried out. The objective of this paper is to improve the safety of ISR surgery by providing detailed anatomical explanations.

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Objective: To document the anatomical structure of the area anterior to the anorectum passing through the levator hiatus between the levator ani slings bilaterally. Methods: Three male hemipelvises were examined at the Laboratory of Clinical Applied Anatomy, Fujian Medical University. (1) The anatomical assessment was performed in three ways; namely, by abdominal followed by perineal dissection, by examining serial cross-sections, and by examining median sagittal sections. (2) The series was stained with hematoxylin and eosin to enable identification of nerves, vessels, and smooth and striated muscles. Results: (1) It was found that the rectourethralis muscle is closest to the deep transverse perineal muscle where the longitudinal muscle of the rectum extends into the posteroinferior area of the membranous urethra. The communicating branches of the neurovascular bundle (NVB) were identified at the posterior edge of the rectourethralis muscle on both sides. The rectum was found to be fixed to the membranous urethra through the rectourethral muscle, contributing to the anorectal angle of the anterior rectal wall. (2) Serial cross-sections from the anal to the oral side were examined. At the level of the external anal sphincter, the longitudinal muscle of the rectum was found to extend caudally and divide into two muscle bundles on the oral side of the external anal sphincter. One of these muscle bundles angled dorsally and caudally, forming the conjoined longitudinal muscle, which was found to insert into the intersphincteric space (between the internal and external anal sphincters). The other muscle bundle angled ventrally and caudally, filling the gap between the external anal sphincter and the bulbocavernosus muscle, forming the perineal body. At the level of the superficial transverse perineal muscle, this small muscle bundle headed laterally and intertwined with the longitudinal muscle in the region of the perineal body. At the level of the rectourethralis and deep transverse perineal muscle, the external urethral sphincter was found to occupy an almost completely circular space along the membranous part of the urethra. The dorsal part of the external urethral sphincter was found to be thin at the point of attachment of the rectourethralis muscle, the ventral part of the longitudinal muscle of the rectum. We identified a venous plexus from the NVB located close to the oral and ventral side of the deep transverse perineal muscle. Many vascular branches from the NVB were found to be penetrating the longitudinal muscle and the ventral part of rectourethralis muscle at the level of the apex of the prostate. The rectourethral muscle was wrapped ventrally around the membranous urethra and apex of the prostate. The boundary between the longitudinal muscle and prostate gradually became more distinct, being located at the anterior end of the transabdominal dissection plane. (3) Histological examination showed that the dorsal part of the external urethral sphincter (striated muscle) is thin adjacent to the striated muscle fibers from the deep transverse perineal muscle and the NVB dorsally and close by. The rectourethral muscle was found to fill the space created by the internal anal sphincter, deep transverse perineal muscle, and both levator ani muscles. Many tortuous vessels and tiny nerve fibers from the NVB were identified penetrating the muscle fibers of the deep transverse perineal and rectourethral muscles. The structure of the superficial transverse perineal muscle was typical of striated muscle. These findings were reconstructed three-dimensionally. Conclusions: In intersphincteric resection or abdominoperineal resection for very low rectal cancer, the anterior dissection plane behind Denonvilliers' fascia disappears at the level of the apex of the prostate. The prostate and both NVBs should be used as landmarks during transanal dissection of the non-surgical plane. The rectourethralis muscle should be divided near the rectum side unless tumor involvement is suspected. The superficial and deep transverse perineal muscles, as well as their supplied vessels and nerve fibers from the NVB. In addition, the cutting direction should be adjusted according to the anorectal angle to minimize urethral injury.

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Transanal total mesorectal resection (taTME) has come a long way since it was first used in the clinic in 2010.The learning curve of this procedure is long due to different surgical approaches, different perspectives and different anatomical positions. Many surgeons experience complications during this procedure. Although the advantages and problems of this procedure have been reported in much literature, the anatomy and operation methods of taTME introduced in literatures and training centers are too complicated, which makes many surgeons encounter difficulties in carrying out taTME surgery. According to the author's experience in learning and carrying out this operation, spatial expansion process of ultralow rectal cancer was divided into three stages. At each stage, according to different pulling forces, three different schemes of triangular stability mechanics model were adopted for separation. From point to line, from line to plane, the model can protect the safety of peripheral blood vessels and nerves while ensuring total mesorectal excision . This model simplifies the complex surgical process and is convenient for beginners to master taTME surgical separation skills.

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Intersphincteric resection (ISR) has been performed as an ultimate sphincter-sparing strategy in selected patients with low rectal cancer. Accumulating evidence suggests that ISR may be an interesting alternative to abdominoperineal resection to avoid a permanent stoma without compromising oncological outcomes. However, bowel dysfunction is a most common consequence of ISR not to be neglected. To date, limited clinical research has reported functional and quality of life outcomes according to patient-reported outcome measures. Also, data concerning management of low anterior resection syndrome are scarce due to lack of quality evidence. Therefore, this review provides an up-to-date summary of systematic assessment (including function, quality of life, manometry and morphology) and bowel rehabilitation for ISR patients. Postoperative anal function is often assessed by a combination of scales, including the Incontinence Assessment Scale, the Gastrointestinal Function Questionnaire, the Specific LARS Assessment Scale and the Faecal Diary. The condition-specific Quality of Life Scale is more appropriate for Quality-of-life measures in fecal incontinence after ISR. Patients' physiological function after ISR can be assessed using water- or high-resolution solid-state anorectal manometry. Anatomical and morphological changes can be assessed using defecography and 3D endorectal ultrasound. Electrical stimulation and biofeedback, pelvic floor exercises, rectal balloon training, transanal irrigation and sacral neuromodulation are all options for post-operative rehabilitation.

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The theory of membrane anatomy has been widely used in the field of colorectal surgery. The key point to perform high quality total mesorectal excision (TME) and complete mesocolic excision (CME) is to identify the correct anatomical plane. Intraoperative identification of the various fasciae and fascial spaces is the key to accessing the correct surgical plane and surgical success. The landmark vessels refer to the small vessels that originate from the original peritoneum on the surface of the abdominal viscera during embryonic development and are produced by the fusion of the fascial space. From the point of view of embryonic development, the abdominopelvic fascial structure is a continuous unit, and the landmark vessels on its surface do not change morphologically with the fusion of fasciae and have a specific pattern. Drawing on previous literature and clinical surgical observations, we believe that tiny vessels could be used to identify various fused fasciae and anatomical planes. This is a specific example of membrane anatomical surgery.