低位直肠癌手术膜解剖——单中心研究进展

Fascial anatomy of surgery for low rectal cancer:a single-center experience

全直肠系膜切除术(total mesorectal excision, TME)是中低位直肠癌的手术标准。对直肠癌手术相关局部解剖、自主神经解剖和膜解剖结构的充分认识,有助于保功能TME的常态化开展。该文对福建医科大学附属协和医院结直肠外科单中心TME相关解剖的系列研究结果进行了回顾:左腹膜后间隙在头侧靠近肠系膜下动脉血管蒂根部存在疏松区域,是开始左腹膜后间隙分离的理想起点,分离过程中需及时切断左原始后腹膜,缩短分离距离。在部分进展期病例中选择性采用肠系膜下动脉鞘内分离技术,可在保证肠系膜下丛平面下肿大淋巴结清扫的基础上,最大限度保存肠系膜下丛左侧束。因直肠骶骨筋膜所致的特有的直肠环周筋膜分布模式,建议直肠环周分离时遵循“后-前-侧”的分离顺序。保留部分Denonvilliers筋膜的直肠前间隙分离策略有助于保证直肠前方系膜的完整切除,并保护精囊腺水平的神经血管束(neurovascular bundle, NVB)。对前列腺水平NVB脂肪垫走行和解剖本质的理解,有助于从整体角度保护之。理解直肠尿道肌及其与直肠纵肌移行结构间NVB的分布,经会阴入路分离时,应以前列腺和双侧NVB为标记,靠近直肠侧切断直肠尿道肌。

[Abstract]Total mesorectal excision(TME)has emerged as a gold standard treatment for patients of mid-low rectal cancer.To enhance the efficacy of TME while preserving functionality,it is crucial to gain a comprehensive understanding of surgical anatomy associated with this procedure.This includes an in-depth knowledge of regional anatomy,fascia anatomy and autonomic nervous system.The present study was intended to summarize a series of research conducted on TME-related anatomy.Notably,our findings revealed the presence of a loosely connected region within left retroperitoneal space,adjacent to vascular pedicle of inferior mesenteric artery.This region served as an optimal starting point for dissecting left retroperitoneal space.For separating left retroperitoneal space during lateral or central approaches,it was necessary to transect left parietal peritoneum,serving as an anatomical basis for"staggered layer phenomenon".In selected advanced cases,intrasheath separation of inferior mesenteric artery with high ligation at its root might be performed for preserving left sheath/trunk of inferior mesenteric artery.Prehypogastric fascia acted as a"fascia barrier"during constant posterior-to-anterior dissection of lateral space.Additionally,pelvic plexus merged with prehypogastric fascia,an outer layer of rectosacral fascia laterally.Therefore,prior to dissecting lateral spaces,it was vital to initially dissect anterior rectal space.After performing a"U"-shaped incision of Denonvilliers'fascia,dissecting lateral space should proceed from anterior to posterior.Subsequently,lateral attachment of rectosacral fascia was transected to ensure the integrity of mesorectum while avoiding injuries to pelvic plexus.Partial preservation of Denonvilliers'fascia helped to mitigate the risk of anterior mesorectal disruption and minimize the potential injuries to neurovascular bundles(NVB)at the level of seminal vesicles.Nerve fibers from NVB at the prostate level were small and their functional zones could not be distinguished intraoperatively.Therefore it was crucial to protect fat pad of neurovascular bundles at the prostate level as a whole.Having a distict understanding of morphology of fat pad of NVB at the prostate level provided valuable surgical guidance for dissecting this critical area.In cases of intersphincteric resection or abdominoperineal resection for very low rectal cancer,anterior dissection plane behind Denonvilliers'fascia disappeared at the level of prostate apex.Prostate and NVB should be employed as landmarks during transanal dissection of non-surgical plane.Rectourethralis muscle should be divided adjacent to rectum side unless there was suspicion of tumor involvement.