Pseudoaneurysms of the middle rectal artery are rare. When encountered, these have the potential for significant morbidity and mortality due to bleeding and potential rupture. Endovascular embolization is a feasible option in the management of these pseudoaneurysms. The present report describes a case of a 43-year-old male presenting with hemorrhagic shock secondary to lower gastrointestinal bleeding one day after undergoing excision of an external perineal condyloma, incision and drainage of a perirectal abscess, and biopsy of a perianal mass. Angiographic imaging revealed a right middle rectal artery pseudoaneurysm. Selective embolization of the right middle rectal artery and bilateral superior rectal arteries was successfully performed. At the two-week post-embolization follow-up, hemoglobin was stable, and the patient reported normal bowel movements with no episodes of bleeding per rectum.

OBJECTIVE: This study aimed to identify cases in which lateral lymph node (LLN) dissection (LLND) can be excluded by clarifying preoperative factors, including an evaluation of the middle rectal artery (MRA), associated with LLN metastasis.
METHODS: Fifty-five consecutive patients who underwent preoperative positron emission tomography-computed tomography (PET/CT) and total mesorectal excision with LLND for rectal cancer were included. We retrospectively investigated the preoperative clinical factors associated with pathological LLN (pLLN) metastasis. We analyzed the regions of pLLN metastasis using MRA.
RESULTS: pLLN metastasis occurred in 13 (23.6%) patients. According to a multivariate analysis, clinical LLN (cLLN) metastasis based on short-axis size and LLN status based on PET/CT were independent preoperative factors of pLLN metastasis. The negative predictive value (NPV) was high (97.1%) in patients evaluated as negative based on PET/CT and cLLN short-axis size. MRA was detected in 24 patients (43.6%) using contrast-enhanced CT, and there was a significant relationship between pLLN metastasis and the presence of MRA. pLLN metastasis in the internal iliac region but not in the obturator region was significantly correlated with the presence of MRA.
CONCLUSIONS: Combined cLLN metastasis based on short-axis size and PET/CT showed a higher NPV, suggesting this to be a useful method for identifying cases in which LLND can be excluded.

Endometriosis is a common benign gynecological disease characterized by the presence of endometrial glands and stroma outside the uterus. It can be defined as endometrioma, superficial peritoneal endometriosis or deep infiltrating endometriosis (DIE) depending on the location and the depth of infiltration of the organs. In 5%-12% of cases, DIE affects the digestive tract, frequently involving the distal part of the sigmoid colon and rectum. Surgery is generally recommended in cases of obstructive symptoms and in cases with pain that is non-responsive to medical treatment. Selection of the most optimal surgical technique for the treatment of bowel endometriosis must consider different variables, including the number of lesions, eventual multifocal lesions, as well as length, width and grade of infiltration into the bowel wall. Except for some major and widely accepted indications regarding bowel resection, established international guidelines are not clear on when to employ a more conservative approach like rectal shaving or discoid resection, and when, instead, to opt for bowel resection. Damage to the pelvic autonomic nervous system may be avoided by detection of the middle rectal artery, where its relationship with female pelvic nerve fibers allows its use as an anatomical landmark. To reduce the risk of potential vascular and nervous complications related to bowel resection, a less invasive approach such as shaving or discoid resection can be considered as potential treatment options. Additionally, the middle rectal artery can be used as a reference point in cases of upper bowel resection, where a trans mesorectal technique should be preferred to prevent devascularization and denervation of the bowel segments not affected by the disease.

This study aimed to clarify the anatomy of middle rectal artery and pelvic vasculature patterns, and to provide schematic information in a manner applicable to the total mesorectal excision. Forty sides of pelvis from 20 formalin-embalmed cadavers (10 male, 10 female) were dissected, and all the pelvic vasculatures from the internal iliac artery were investigated, focusing on the middle rectal artery. Middle rectal arteries were classified into major types depending on their vascular origins. Each type was subdivided into minor types according to variability of the pelvic vasculature. A middle rectal artery was identified in 18 out of 20 cadavers, and in 25 out of 40 pelvic sides. In most cases, the middle rectal artery originated from the internal pudendal artery or inferior gluteal artery. These two arteries arose directly from the anterior trunk of the internal iliac artery or were bifurcated from the gluteal-pudendal trunk. In rare cases, these arteries arose from the posterior trunk of the internal iliac artery. The other origins of the middle rectal artery included the gluteal pudendal trunk, inferior vesical artery, internal iliac artery, obturator artery, and the prostatic artery, and the pelvic vasculatures in these cases also presented variability. The detailed anatomical findings related to the middle rectal artery and pelvic vasculatures are noteworthy for their improved clinical applicability.

The main aim of this study is to present, describe and compare the most significant anatomical classifications of the internal iliac artery (IIA) and its branches, their pros and cons, to relate them to clinical practice and note their clinical importance, and to offer a new classification based on number of main vessels origins. Many classifications covering the detailed morphology of the IIA have been developed, focusing on the destination of vessels making it possible to determine the name and type of branching precisely. However, because the allocation criteria are overdetailed and of doubtful accuracy, these classifications have become impractical for clinical practice and advanced statistical calculations. The argument of this research paper is that highly variable vascularized regions should be classified from either an anatomical point of view to determine detailed morphology aspects or a clinical perspective. Presented classification proposes unification of many branching types presented among various classifications, which look identical when determining the origin pattern from the main vessel and differ only in the destination point of the vessel, what brings clarity and increases the statistical usefulness of the collected data. This should translate into better cooperation between scientists and clinicians and thus benefit patients. The paper proposes a new, clinically useful classification based on the model of vessel origins from the main stem. The IIA is the main vascular supply to the pelvic region, so precise knowledge of origin and its branching pattern is essential for all clinicians, especially for general and orthopaedic surgeons, gynecologists, obstetricians and urologists.

The concept of total mesorectal resection provides a quality control standard that can be followed for radical resection of rectal cancer, but some anatomical problems are still controversial. Compared with traditional open surgery, laparoscopic radical rectal surgery has better surgical vision, better neurological protection, better operating space. However, if the surgeon has insufficient understanding of the anatomy, collateral damage may occur, such as uncontrollable bleeding during the operation, postoperative urination and defecation dysfunction and so on. Based on the interpretation of the researches at home and abroad, combined with the clinical experience, we elucidate some associated issues, including anatomic variation of inferior mesenteric vessels, the controversy of inferior mesenteric artery ligation plane, the controversy of lymph node dissection in No. 253, the anatomical variation of middle rectal artery, and the anatomical controversy of lateral lymph node dissection in rectal cancer, in order to provide better cognitive process for the clinical front-line surgeons.
全直肠系膜切除的理念为直肠癌的根治手术提供了可以遵循的质量控制标准，但是尚有部分解剖学问题存在争议。腹腔镜直肠癌根治术虽然具有更好的手术视野、更佳的神经功能保护、更大的操作空间，但若术者对解剖结构或解剖变异认知不足，可能会出现术中不可控制的出血、术后排尿排粪功能障碍等副损伤。笔者通过对国内外研究的分析总结，并结合临床经验，针对直肠癌根治术涉及的几个解剖争议问题，包括肠系膜下血管解剖及变异、肠系膜下动脉离断平面的争议、第253组淋巴结清扫的争议、直肠中动脉的解剖学变异及直肠癌侧方淋巴结清扫的解剖学争议等进行阐述，旨在为临床外科医师提供一个更好的认知过程。.

OBJECTIVE: Lateral lymph node (LLN) metastasis is one of the leading causes of local recurrence in patients with lower rectal cancer. Unfortunately, no diagnostic biomarkers are currently available that can predict LLN metastasis preoperatively. Accordingly, we investigated the relationship between the middle rectal artery (MRA) identified by contrast-enhanced magnetic resonance imaging (ceMRI) and LLN metastases.
METHODS: Data from 102 patients with lower rectal cancer who underwent surgery, and were evaluated by preoperative ceMRI, between 2008 and 2016 were reviewed retrospectively. Two expert radiologists evaluated the MRA findings. The diagnostic performance of MRA for LLN metastasis was evaluated by a multivariate analysis with conventional clinicopathological factors.
RESULTS: The MRA was detected in 67 patients (65.7%), including 32 (31.4%) with bilateral MRA and 35 (34.3%) with unilateral MRA. The tumor size, presence of the MRA, and clinical LLN status were significantly correlated with LLN metastasis. A multivariate analysis demonstrated that the presence of MRA (P = 0.045) and clinical LLN status (P = 0.001) were independent predictive factors for LLN metastasis. Furthermore, the sensitivity and negative predictive value of MRA for LLN metastasis were 95% and 97.1%, respectively.
CONCLUSIONS: We successfully demonstrated that MRAs could be clearly detected by ceMRI, and the presence of MRA robustly predicted LLN metastasis in patients with lower rectal cancer, highlighting its clinical significance in the selection of more appropriate treatment strategies.
BACKGROUND: Trial registration number: retrospectively registered 2126 Trial registration date of registration: August 23, 2019.

Colorectal surgeons have focused on the lateral structure of rectum for a long time and lateral ligament is the common term to depict this structure. A better understanding of lateral rectal structure could be beneficial to performing the total mesorectum excision (TME) procedure and protecting patients\' urinary, sexual and defecation function. The main controversies focus on two aspects: (1) Does the lateral ligament exist? (2) What dose it contain? Does the middle rectal artery exist? Up to now, anatomic studies have failed to reach consensus on the lateral rectal structure. However, surgeons do find the lateral rectal ligament during surgery and it may be the pathway for lateral lymph node metastasis in rectal cancer. The lateral rectal structure contains the middle rectal artery, nerve branches, lymphatics and adipose fibrous tissue around them. We summarize our clinical experience and conclude that the middle rectal artery appears in lateral ligament constantly but some of them are too small to be easily observed. Therefore, regarding the perspective of membrane anatomy, embryology and surgery, this structure may be more appropriate to be called the \"lateral mesorectum\". We propose this new term based on the previous literature and our own experience for the readers\' reference.
直肠侧方结构一直是人们关注的焦点，目前通用的称谓是直肠\"侧韧带\"。对其进行深入的认识，有助于更好地完成全直肠系膜切除手术，并保护患者的泌尿生殖系统功能及控制排粪功能。目前围绕直肠侧方结构的争论点主要集中在：（1）直肠\"侧韧带\"是否存在。（2）直肠侧方结构的组成是什么，直肠中动脉是否存在。目前解剖上对直肠侧方结构的研究并未达成共识，但临床手术中发现，直肠\"侧韧带\"确实存在，并且是直肠癌发生侧方淋巴结转移的途径。直肠\"侧韧带\"内包含直肠中动脉、神经分支、淋巴管以及包裹的脂肪纤维组织。笔者总结临床经验认为，直肠中动脉在\"侧韧带\"中恒定出现，只是部分动脉血管直径较小，难以被观察到。从解剖学、胚胎学和外科手术的角度考虑，笔者建议，将直肠\"侧韧带\"这一与直肠系膜相通、并包含多种组织的结构称为直肠\"侧系膜\"可能更为合适，这也更加符合直肠癌发生侧方转移的解剖基础。本文结合既往文献和本团队临床经验，提出这一新命名供大家讨论。.

A middle rectal artery arising from the lateral sacral artery (MRAls) in the right pelvis of a 99-year-old male was observed. Although variations of the origin of the middle rectal artery have been reported on many occasions, there are few descriptions of the trajectory in the literature. In our case, the MRAls branched from the lateral sacral artery on the sacral surface close to the third sacral sympathetic ganglion and immediately penetrated the third sacral splanchnic nerve and the parasympathetic pelvic splanchnic nerve from the ventral ramus of the forth sacral nerve. The MRAls entered in the lateral wall of the rectal ampulla without giving off a prostatic branch. Preservation of the pelvic autonomic nerves are crucial in rectal cancer excision to preserve the autonomic functions. The close topography of the MRAls to the origin of the fine autonomic nerves should be noted.

The middle rectal artery is a very important anatomical structure in rectal cancer surgery. It is the only vessel that penetrates through the proper rectal fascia into the pelvic cavity, and therefore threatens the integrity of total mesorectal excision. Moreover, it is very closely related to the lateral lymphatic drainage root. The definition of the middle rectal artery is ambiguous, and different frequencies, origins, and trajectories have been reported in various papers. The frequency of the middle rectal artery is reported to range from 12 to 97 %. Traditionally, the middle rectal artery is described as an artery that penetrates the pelvic plexus from the lateral side along with the lateral ligament; the frequency of this lateral type of middle rectal artery ranges from 20 to 30 %. However, the reports that describe higher frequency values also consider another type of middle rectal artery, which penetrates the neuro-vascular bundle from the antero-lateral direction; this antero-lateral type of middle rectal artery tends to be a small vessel, and frequently forms a common trunk with the prostatic artery. With advancements in endoscopic surgery, the knowledge of the precise anatomy of this structure is becoming more crucial for optimal rectal cancer surgery.