Pelvic anatomy for colorectal surgeons

INTRODUCTION: recent advances in rectal surgery include total mesorectal excision and preservation of the autonomic pelvic nerves, so that colorectal surgeons have to get some information on the embryology of the rectum, on the complex anatomy of the pelvic floor and on the distribution of lymphatic nodes. Embryology includes the formation of the hindgut during the first month of the embryo and the subsequent formation of the rectum and anal canal. The mesorectum contains the blood vessels and the lymphatic nodes. To totally excise the mesorectum, the surgeon should follow the "holy plane" described by Heald, between the perirectal fascia and the pelvic fascia. Doing this, the surgeon has the best chance to preserve the autonomic pelvic nerves that comprise the superior hypogastric plexus, the right and left hypogastric nerves and the right and left inferior hypogastric plexuses.     

Does perifascial rectal excision (i.e. TME) when combined with the autonomic nerve‐sparing technique interfere with operative radicality?

Objective The lymphatic drainage from the rectum was studied to evaluate if the autonomic nerve sparing dissection may interfere with the operative radicality and might result in metastatic lymph nodes being overlooked and left in situ. Patients and methods 50 consecutive patients had an extended extrafascial rectal excision resection for cancer. In 19 of the 50 patients activated carbon particles (CH40) were injected preoperatively into the rectum. The autonomic nerves with surrounding connective tissue were serially dissected from the resected specimen , carefully sliced at 5‐mm intervals and collected for histological study. Lymph nodes along the axial and lateral drainage routes were examined, and the inclusion of CH40 in the nodes was microscopically studied according to the site of CH40 injection. Results Lymph nodes within the connective tissue along the dissected autonomic nerves were demonstrated in 47 of the 50 cases. Two of 50 cases had positive nodes along preaortic plexus or pelvic plexus, and a case with nodal involvement along the pelvic plexus had poor prognosis in spite of nerve excision. CH40 when injected into the rectum above the peritoneal reflection was demonstrated in the vast majority of the axial nodes, while in only one lymph node along the preaortic plexus when injected in the rectum above the peritoneal reflection. On the other hand when injected in the rectum below the peritoneal reflection, CH40 was demonstrated both in axial and lateral nodes as well as in lymph nodes along bilateral pelvic plexuses, right hypogastric nerve, superior hypogastric plexus, preaortic plexus and mesenteric plexus as well. Conclusions When located above the peritoneal reflection a rectal carcinoma will spread preferentially along the upper axial route, while a carcinoma located below the peritoneal reflection will also spread laterally and along the autonomic nerves. It was inferred that lymphatic flow along the autonomic nerves came up from the rectum below the peritoneal reflection mainly through a so‐called lateral ligament but its clinical significance was negligible. Therefore doing TME with autonomic nerve preservation does not imply a less radical surgery from the point of lymphatic spread.     

直肠切除术中保留盆腔内脏神经的解剖学基础及要点

目的了解盆腔内脏神经的走行及与盆腔筋膜的关系,寻找安全的操作平面,减少直肠癌手术中对内脏神经的损伤。方法通过解剖12例人骨盆标本,观察盆腔内脏神经的走向分布及与筋膜间隙的关系。结果腹下神经全程走行于骶前筋膜内,下腹下丛走行于盆壁层筋膜内,并于直肠2点及10点处（截石位）在多个平面交叉穿入Denonvilliers筋膜汇入泌尿生殖血管束,Denonvilliers筋膜内存在横行的神经交通支。结论直肠后方及侧方的手术操作平面在直肠固有筋膜与骶前筋膜之间靠近直肠固有筋膜一侧,在直肠前方的手术操作应注意保护直肠2点及10点位置的泌尿生殖神经血管束及Denonvillers筋膜内的神经交通支。     

从盆腔筋膜的外科解剖来理解直肠全系膜切除术的层次

目的探讨直肠系膜与盆腔筋膜和神经的关系，以明确直肠全系膜切除术合理的切除平面。方法对24具尸体的盆腔进行解剖。结果直肠周围的层次是连续的，可以分为2段3层，2段指耻骨联合至坐骨棘和坐骨棘至骶岬；3层分别为脏筋膜、膀胱腹下筋膜和壁筋膜。在膀胱腹下筋膜与脏筋膜之间存在盆丛及其膀胱、子宫神经分支，而在脏、壁筋膜之间存在腹下神经和盆内脏神经。结论直肠全系膜切除术的层次在直肠后方为脏、壁筋膜之间，而在直肠侧方实际上位于脏筋膜和膀胱腹下筋膜之间。侧后方的腹下神经、侧前方的盆丛及其分支是正确层次的标记。     

How to Optimize Autonomic Nerve Preservation in Total Mesorectal Excision: Clinical Topography and Morphology of Pelvic Nerves and Fasciae

Background  Urogenital dysfunction after rectal and pelvic surgery was significantly decreased with the introduction of nerve-preserving dissection and total mesorectal excision (TME). Profound topographic knowledge of the pelvic connective tissue spaces is indispensable for identification and preservation of autonomic pelvic nerves. The purpose of this cadaver study was to highlight the course of important autonomous nerve structures and to identify potential injury sites. Methods  Eleven cadavers were dissected according to TME with subsequent preparation of the pelvic nerves. The pelves of further three cadavers were sliced horizontally and cubed. Specimens were harvested and processed for light microscopy and immunohistochemistry to analyze both fascia and the types of nerves and their localization. Results  The neurovascular bundle, arising from the inferior pelvic plexus, shows the highest nerve density. At the lateral edge of Denonvilliers’ fascia, it pierces the parietal pelvic fascia. Several fine nerve branches spread into the loose periprostatic tissue up to the prostate or pass the prostate toward the urinary bladder. En route, we consistently find perikarya of autonomic nerves. Within the mesorectum, nerve fibers are distributed heterogeneously with laterally high densities, ventrally and dorsally low densities. Conclusion  The highest risk for pelvic nerve damage—apart from lesions of the superior hypogastric plexus itself—is anterolaterally of the rectum where the neurovascular bundle releases from the pelvic sidewall. Careful dissection helps to identify and protect these nerve structures. The retroprostatic Denonvilliers’ fascia contains no important nerve structures. Presented at the 42nd World Congress of the International Society of Surgery (ISS/SIC), 26–30 August 2007, Montréal, Canada.     

直肠癌根治术中保留骨盆自主神经的神经解剖学基础及临床意义

目的　探讨直肠癌根治术中保留神经的解剖学基础。　方法　解剖 6例完整尸体标本(男 4例 ,女 2例 )和 4例直肠及盆腔未受破坏的矢状半骨盆标本 ,观察骨盆神经组成及走行。　结果　显露下腹神经干 ,确定其在第 5腰椎处分为左、右下腹神经。其特点是较为粗大 ,位置固定 ,在腹主动脉分叉处易找到 ,呈网状联系 ,质地较实 ,为灰白色 ,与腹主动脉较近。分叉后左右下腹神经还有较粗大分支。骨盆内脏神经在大体标本上较难辨认 ,在矢状半骨盆标本中见到发自骶前孔 2～ 4的骨盆内脏神经 ,该神经较纤细 ,在侧韧带处呈丛状的细小纤维。　结论　保留下腹神经临床上较易完成。保留骨盆内脏神经则须细心操作 ,预保留神经的一侧在侧韧带水平的手术操作应尽量贴近直肠进行。     

直肠周围筋膜和间隙环形分布模式的解剖学观察

目的阐明与全直肠系膜切除术密切相关的直肠周围筋膜和间隙的解剖结构。方法利用21具固定尸体（男15、女6）制作30个半盆腔和6个3／4盆腔．解剖和观察直肠周围筋膜和间隙。结果直肠后方由前至后存在3层筋膜：包绕直肠系膜的直肠固有筋膜、骶前筋膜和与骶骨骨膜相愈着的梨状肌筋膜。直肠系膜包含两个部分：经典的由直肠固有筋膜所包绕的后外侧脂肪为其后部．由Denonvilliers筋膜后叶包绕的直肠前脂肪为其前部。骶前筋膜向前延续于Denonvilliers筋膜前叶．将直肠系膜和梨状肌筋膜之间的间隙分为前方的直肠后间隙和后方的骶前间隙。直肠后间隙向头侧与左结肠后间隙交通,向前与Denonvilliers筋膜两叶之间的间隙（直肠前间隙）交通。结论以直肠系膜为中心,直肠固有筋膜、骶前筋膜和盆壁肌肌膜自内向外呈环形分布。骶前筋膜将直肠周围的间隙分为中心的直肠后间隙和外周的骶前间隙两个环形间隙。直肠后间隙是全直肠系膜切除术的理想外科平面。     

直肠系膜两个无血管层次的解剖特征

目的：探讨全直肠系膜切除的解剖学基础,明确全直肠系膜切除的切除平面。方法：对23具尸体的盆腔进行解剖,观察直肠系膜与周围筋膜、神经的关系。结果：在直肠的侧后方存在两个无血管层次．即直肠周围脂肪与脏筋膜之间的层次及脏层筋膜与壁层筋膜之间的层次。各层次内存在不同的组织结构,在直肠与脏筋膜间存在着直肠侧韧带．在脏、壁层筋膜间存在着腹下神经和盆内脏神经。结论：全直肠系膜切除的切除范围应包括脏层筋膜在内,解剖层次应为脏、壁层筋膜间层次;术中通过观察两个无血管层次中的结构可以判定是否进入了正确的全直肠系膜切除的切除层次。     

腹腔镜直肠癌低位前切除术

腹腔镜直肠癌低位前切除术已在临床上受到广泛认可。术中手术层面的识别与游离、盆腔自主神经的保护对于手术成功与否以及患者术后生活质量尤为重要。腹腔镜直肠癌低位前切除术中需注意：(1)直肠系膜与神经前筋膜之间游离;(2)紧贴直肠系膜游离间隙;(3)保证直肠系膜后方、两侧方和前方的完整;(4)TME手术直肠系膜终止线位于肛门直肠环,游离应到位,不能残留直肠系膜。实践证实,基于膜解剖的直肠癌全系膜切除有助于盆腔自主神经保护以及实现肿瘤的根治性切除。     

高分辨率MRI显示直肠周围筋膜结构

目的观察直肠周围筋膜高分辨率MRI成像表现。方法对50名正常志愿者行盆腔MRI常规T1WI、T2WI及高分辨率T2WI扫描,观察直肠周围筋膜结构,比较各序列对直肠周围筋膜的显示情况。结果高分辨率T2WI序列对前、后、左、右方直肠系膜筋膜显示率分别98%、100%、94%、90%;对Denonvilliers筋膜、骶前筋膜及腹膜返折显示率分别为58%、54%、70%。高分辨率T2WI对前、左、右方筋膜、Denonvilliers筋膜及腹膜返折的显示率明显高于盆腔常规T1WI、T2WI(P均0.05);对后方直肠系膜筋膜、骶前筋膜显示率略高于常规T1WI、T2WI,但差异无统计学意义(P均0.05)。结论高分辨率T2WI显示直肠周围筋膜结构优于盆腔常规MRI序列。     

Surgical anatomy of pelvic nerves

A good knowledge of the anatomy of the mesorectum and pelvic autonomic nerves allows the colorectal surgeon to reconcile both oncologic and functional results in rectal cancer excision. The author describes the anatomy of the systemic and autonomic pelvic nerves and describes techniques designed to avoid nerve damage during rectal cancer excision.     

Optimal lymph node dissection for colorectal cancer]

Previous studies on the distribution of positive lymph nodes have revealed that the colon should be resected 10 cm from the tumor on both sides and that the intermediate nodes along the main vessel should be dissected in patients with colon cancer. In rectal cancer, superior lymphatic spread along the inferior mesenteric artery (IMA) is the main metastatic route. The IMA should be dissected immediately after the bifurcation of the left colic artery, and the intermediate lymph nodes should be removed. The positive rate of the lateral lymph nodes is about 10%. The rate of local failure is high and the prognosis is poor in patients with positive lateral lymph nodes, even if the lateral lymph nodes have been dissected. However, it has been reported that lateral lymph node dissection combined with excision of the internal iliac vessels results in good disease-free survival in patients with positive lateral nodes. Therefore the indications for lateral node dissection remain controversial. Lymphatic spread into the mesorectum on the anal side has been shown to be an important factor in local failure. The mesorectum should be resected for up to 4 or 5 cm from the inferior tumor margin in middle rectal cancer, and the entire mesorectum should be removed in lower rectal cancer. Nerve tissue preserved in pelvic autonomic nerve-preserving surgery contains a small amount of lymphoid tissue and lymph nodes. Therefore the extent of lymph node dissection and the area of autonomic nerves to be preserved based on tumor site or tumor penetration remain controversial.     

Rectal carcinoma. Optimizing therapy by knowledge of anatomy with special reference to the mesorectum]

The connective tissue spaces of the pelvis and pelvic floor originate from an urogenital and perirectal mesenchymal cell complex, which can be clearly discerned. In the adult, the final compartments, which arise from these distinct tissue complexes, are still functionally separated. The perirectal tissue gives rise to the rectal fascia or rectal adventitia, also known as mesorectum. The connective tissue space between rectal and parietal pelvic fascia can be dissected as a plane free of vessels and nerves. Surgical dissection along this plane with complete mesorectum excision results in reliable excision of all relevant lymphatic pathways with extensive preservation of continence and sexual function.     

3D腹腔镜NOSES直肠癌根治术

五孔法,按TME及神经功能保护原则手术,骶岬前方切开后腹膜,打开血管鞘,分离直肠上动脉、肠系膜上动脉及左结肠动脉,清扫腹主动脉(253)淋巴结,结扎切断肠系膜下动静脉,沿Denonvilliers筋膜分离,注意保护腹下神经丛。游离乙状结肠及降结肠系膜,向下沿盆筋膜脏层和壁层之间游离至肛提肌平面,注意保护盆自主神经。切断直肠侧韧带游离直肠侧方,前方打开腹膜返折部及Denonvilliers筋膜向下游离至肿瘤下方5 cm。切断乙状结肠,3-0抗菌微乔线荷包缝合一圈,切断直肠,经肛门置入吻合器枪身,激发完成吻合。     

Cadaveric dissection for the rectal surgeon

The benefits of total mesorectal excision are due to the complete excision of the mesorectum with preservation of the pelvic autonomic nerve plexuses, the hypogastric nerves and nervi erigentes. Several important structures are incompletely seen at operation, and cadaveric dissection of an intact lower trunk and a sagittally hemisected pelvis is a valuable exercise in demonstrating them. A method for dissection is described which illustrates the key anatomical points.     

男性泌尿生殖层的层面解剖及其临床意义研究

目的 观察并描述男性泌尿生殖层的层面解剖学形态,探讨该层面在结直肠手术中的临床意义。
方法 采用层面解剖学方法解剖10具男性尸体躯干与20具盆腔标本,系统地描述泌尿生殖层的解剖形态,并与相应腹腔镜下解剖结构相比较。结果 男性泌尿生殖层为泌尿生殖筋膜包被,整体结构可分3段--腹段、盆段和精索段。泌尿生殖层腹段头侧由泌尿生殖筋膜紧密愈着于膈下筋膜,外侧与腹横筋膜间形成侧锥筋膜,其腹侧为原始体腔膜形成的后腹膜以及后腹膜与腹内脏器固有筋膜形成的融合筋膜,背侧为腰肌筋膜;腹段在肠系膜下动脉以下,形成位于腹主动脉与下腔静脉前方的独立层面,在盆腔入口处延续为位于中央的盆段和位于两侧的精索段。精索段外侧界为精索血管,内侧界为输尿管,前界为输精管,外被泌尿生殖筋膜,形似三角,经由内环外出至腹股沟管,延伸至睾丸。盆段入盆后包绕在直肠周围下行,直肠后方的泌尿生殖层约在骶4椎体前方融汇于直肠固有筋膜,其内走行腹下神经;直肠侧方泌尿生殖层内为下腹下神经丛以及输尿管、输精管走行,泌尿生殖筋膜脏层覆盖其内侧表面,行向直肠前方,终于精囊腺-前列腺交界,泌尿生殖筋膜壁层覆盖于下腹下神经、输尿管背侧及外侧,下行与膀胱固有筋膜融汇。结论 泌尿生殖层各段构成结肠、直肠周围毗邻层面,该解剖结构对于结直肠手术具有重要的指导意义。     

全直肠系膜切除术的应用

传统的直肠癌根治术后局部复发是影响术后5年生存率的重要因素之一。近年来解剖学研究证明，直肠是具有系膜的脏器，直肠癌可通过多种方式在系膜中播散，这些微转移灶的残留是导致术后局部复发的重要因素。1982年，Heald首次提出了针对中下段直肠癌的全直肠系膜切除术，即直视下在盆筋膜脏层与壁层间锐性分离，完整切除直肠及直肠系膜，同时注意保护自主神经。经过20年的应用，其在降低直肠癌术后复发方面的优势已得到认可，术后吻合口漏、排尿功能及性功能障碍等并发症发生率低，目前已得到广泛应用。     

基于膜解剖的低位直肠癌侧方淋巴结“两间隙”清扫术安全性研究

目的 通过尸体解剖分析基于膜解剖的 “两间隙”侧方淋巴结清扫术的解剖学理论,探讨对低位直肠癌病人行“两间隙”清扫的安全性和可行性。方法 解剖观察24具来源于上海交通大学医学院解剖教研室的成人尸体标本,对与侧方淋巴结清扫术相关的筋膜和间隙进行记录和描述。回顾性分析同济大学附属杨浦医院2018年7月至2020年3月行3D腹腔镜下直肠全系膜切除+“两间隙”侧方淋巴结清扫术的14例低位直肠癌病人的临床资料。结果 所有24具尸体均可以明确解剖出直肠固有筋膜、尿生殖筋膜、膀胱腹下筋膜和闭孔筋膜（壁筋膜）,并在直肠侧方从内至外依次排列。直肠固有筋膜表现为覆盖在直肠及其周围脂肪表面的最内侧薄层筋膜。尿生殖筋膜是位于直肠侧后方的盆腔最为致密的筋膜,其中20例（83.3%）腹下神经位于尿生殖筋膜内;4例（16.7%）腹下神经位于尿生殖筋膜的深面。膀胱腹下筋膜是由脐动脉、膀胱下动脉和膀胱壁组成的“三角形”筋膜。临床实践表明,14例病人均在3D腹腔镜下完成侧方淋巴结清扫。侧方淋巴结清扫术时间为（175±27） min,术中出血量为（50±18）mL,2例病人出现并发症,淋巴漏和下肢疼痛各1例,术后住院时间（11±2） d。3例（21.4%）病人病理学检查证实为侧方淋巴结转移,其中1例为单纯性髂内淋巴结转移,平均侧方淋巴结检出数目（8.4±1.3）枚。结论 “三筋膜”（尿生殖筋膜、膀胱腹下筋膜和闭孔筋膜）构成了侧方淋巴结清扫术的两间隙（膀胱旁间隙和Latzko直肠旁间隙）。基于膜解剖的低位直肠癌侧方淋巴结“两间隙”清扫术依据膜解剖标记完成,层面容易辨识,血管、神经定位明确,初步的手术经验证实临床切实可行,不但可以提高手术的安全性,而且可以保证手术的根治性,值得进一步积累病例验证。