全直肠系膜切除术中神经血管束前列腺部的解剖学观察和临床意义

Anatomical observation and clinical significance of the prostatic part of neurovascular bundle in total mesorectal excision

目的了解在全直肠系膜切除术(TME)直肠末端系膜游离过程中,神经血管束(NVB)前列腺部微出血的概率并探讨其临床意义;对NVB前列腺部的解剖学形态进行观察以探讨其保护策略。方法采用描述性病例系列研究和尸体解剖研究的方法,对NVB前列腺部进行活体和尸体标本解剖学观察。活体标本的观察:从福建医科大学附属协和医院结直肠外科手术视频数据库中,选取2013年11月至2015年3月期间,行腹腔镜保留部分邓氏筋膜TME的38例非连续男性患者的手术录像。通过回顾性复习手术录像,盲法分别评估NVB前列腺部微出血以及泌尿和性功能情况,泌尿功能采用国际前列腺症状评分表(IPSS)评估,性功能采用勃起功能国际问卷(IIEF-5)评估,分析NVB前列腺部微出血与否与术后泌尿和性功能的关系。尸体标本解剖学观察:选择福建医科大学解剖学教研室的4例男性半盆腔尸体标本,采用两种方法进行尸体标本解剖,其一:2个半盆标本,模拟TME手术进行分离,观察NVB前列腺部;其二:另2个半盆标本,采用莱卡刀片从横断面进行连续横切(层厚约1 cm),将NVB前列腺部脂肪垫当做一个整体进行观察。最终将术中的活体解剖观察与相应尸体观察层面进行比对。计数资料组间比较采用Fisher精确概率法检验。偏态分布的计量资料用M(范围)表示,组间比较采用Mann-Whiteny U秩和检验。结果38例患者中位年龄57(31~75)岁,肿瘤距肛缘中位距离6(1~8)cm。21例(55.3%)术中NVB前列腺部微出血(微出血组),17例(44.7%)未见出血(无出血组)。微出血组术后3个月和6个月IPSS评分高于无出血组[7(0~16)分比2(0~3)分,Z=-1.787,P=0.088;2(0~15)分比0(0~2)分,Z=-2.270,P=0.028],而术后12个月两组IPSS评分差异无统计学意义(P>0.05);性功能方面,有23例术前性活跃(IIEF-5≥18分)患者纳入分析,其中无出血组7/8例患者术后12个月性功能恢复至术前水平(定义为IIEF-5下降<3分、且患者主观性功能满意情况恢复至术前水平),而微出血组仅6/15的患者恢复至术前水平,差异有统计学意义(P=0.029)。模拟TME手术分离半盆尸体标本,见NVB前列腺部血管神经走行在直肠前外侧、前列腺后外侧和肛提肌前内侧所构成的狭小的三角空间内,血管神经组织缠绕成团,分支不易辨别。进一步将NVB前列腺部脂肪垫当做一个整体进行尸体和活体比对观察发现,在尸体的前列腺底和前列腺中部水平,NVB前列腺部脂肪垫与直肠系膜关系密切,两者投影线存在较大重叠,是术中NVB前列腺部微出血的高危区。手术视频观察发现,在对应的前列腺底和前列腺中部水平,术中因主刀医师和助手的对抗牵引,使该处NVB前列腺部脂肪垫呈横向走行。其转为纵向走行处为NVB发出的直肠支,张力最大,为易出血区。可清晰锚定数支NVB直肠支,需要采用超声刀紧靠直肠固有筋膜预先凝结。比对发现,该直肠支即为尸体投影线重叠区。结论NVB前列腺部损伤是TME术后排尿和性功能障碍的原因之一,NVB前列腺部神经纤维细小,术中无法辨别其功能分区,需要将NVB血管神经组织和相应脂肪垫当做一个整体进行保护。术中充分理解NVB前列腺部形态,保持适当对抗牵引张力,采用超声刀及时凝结直肠支可保护NVB前列腺部。

Objective To observe the anatomical architecture of the prostatic part of the neurovascular bundle(NVB)in total mesorectal excision(TME).Methods A descriptive cohort study and an anatomical observation study were carried out.A total of 38 male patients with rectal cancer who underwent TME in the Department of Colorectal Surgery at the affiliated Union hospital of Fujian Medical University between November 2013 and March 2015 were included.A total of 4 hemipelvis were examined at the Laboratory of Clinical Applied Anatomy,Fujian Medical University.The following outcomes were observed:1)the clinical significance of bleeding of the prostatic part of NVB:surgical videos were reviewed and the incidence of bleeding was recorded.The urogenital function was assessed using the International Prostate Symptom Score(IPSS)and International Index of Erectile Function(IIEF)score.The correlation between prostatic part bleeding and postoperative urogenital function was evaluated.2)anatomical observation:the vessels,nerve fibers,as well as their surrounding fatty tissue from the prostatic part were treated as a whole,namely,the fat pad of the prostatic part.The anatomical architecture of the prostatic part in the surgical videos was reviewed and interpreted with the cadaveric findings.Categorical variables were compared between groups using a Fisher exact probability.while continuous variables with skewed distribution were compared between groups using the Mann-Whiteny U test.Results The median age of the included 38 patients was 57 years(range,31-75),and the median tumor distance to the anal verge was 6 cm(range,1-8).Of them,a total number of 21(55.3%)patients had bleeding of the prostatic part of NVB(bleeding group),while the rest had not(17 cases,44.7%,non-bleeding group).1)the clinical significance of bleeding of the prostatic part of NVB.The urinary function significantly decreased in patients in the bleeding group according to IPSS score after the 3rd month and the 6rd month of the surgery[7(0-16)vs.2(0-3),Z=-1.787,P=0.088;2(0-15)vs.0(0-2),Z=-2.270,P=0.028].There was no difference regarding the IPSS score between the two groups after 1 year of the surgery(P>0.05).With a total of 23 patients with normal preoperative sexual activity included,87.5%(7/8)of patients in the non-bleeding group can expect to return to their preoperative baseline,this incidence was significantly higher than that of only 40%(6/15)in the bleeding group(P=0.029).2)anatomical observation:for cadaveric observation,the prostatic part of NVB was located in the narrow triangular space composed of anterolateral walls of the rectum,the posterolateral surface of the prostate and the medial surface of the levator ani musculature.The tiny vascular branches and nerve fibers from the prostatic part were hard to identify.The cavernosal nerves cannot reliably be distinguished from the neural supply to the prostate,rectum and levator ani.In the cross-section of levels of prostatic base and mid-prostate in cadaveric hemipelvis specimens,the boundary of the prostatic part fat pad was partly overlapped and merged with the boundary of the mesorectum.Intraoperative observation showed that the areas of overlap referred to the rectal branches from the prostatic part piercing the proper fascia to supply the mesorectum,which carried the largest tension and high risk of bleeding during circumferential dissection toward the perirectal plane.The ultrasonic scalpel was required to pre-coagulate the rectal branches at the point close to the proper fascia of the rectum to prevent bleeding.In the cross-section of the prostatic apex level,the prostatic part approached ventrally and its boundary was away from the boundary of the mesorectum.Conclusions NVB prostatic part injury is one of the causes of urogenital dysfunction after TME.The nerve fibers from the prostatic part were tiny,and its functional zones cannot be distinguished during operation.Therein,the fat pad of the prostatic part should be protected as a whole.Understanding the morphology of the fat pad of the prostatic part provides invaluable surgical guidance to dissect this critical area.When dissecting around the anterolateral rectal wall,appropriate anti-traction tension should be maintained and the rectal branches from the prostatic part should be coagulated with an ultrasonic scalpel to prevent bleeding.