Contribution to the surgical anatomy of the ligaments of the rectum

Imaging for Hemorrhoidal Disease: Navigating Rectal Artery Embolization from Planning to Follow-up

Hemorrhoid disease is very common, affecting greater than one-third of adults. Conservative management and several office-based procedures are useful in the treatment of internal hemorrhoids. Patients with refractory hemorrhoid disease have traditionally been treated with surgical hemorrhoidectomy. Rectal artery embolization has emerged as an alternative to surgical hemorrhoidectomy and has been shown to be safe and effective in case series and clinical trials completed over the past decade. Embolization has significantly less postprocedure pain when compared with surgical hemorrhoidectomy with similar outcomes. Pre- and postprocedure imaging are not routinely performed. Intraprocedural imaging consists of selective catheterization of the superior rectal arteries from the inferior mesenteric artery, and the middle rectal arteries from the internal iliac artery. The inferior rectal artery is seldom embolized due to the supply of the levator ani muscle and skin. To date, intermediate and large particles and fibered and nonfibered coils have been used successfully.

Preoperative factors associated with lateral lymph node metastasis in lower rectal cancer and the evaluation of the middle rectal artery

PURPOSE

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.

CONCLUSION

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.

A novel perspective on constipation secondary to sigmoidocele: a retrospective study

PURPOSE

Sigmoidocele, which is a type of obstructed defecation syndrome (ODS), is a peritoneal hernia of the pelvic floor that has been seldom studied individually. This study investigated the anatomic characteristics of sigmoidocele based on imaging features.

METHODS

This retrospective cohort population comprised adult patients with ODS who underwent defecography between December 2017 and July 2020. Sigmoidocele was classified based on existing criteria. Novel radiological parameters including the vertical distance descended by the sigmoid colon from rest to maximum straining (RMS) and from the inferior border of the sigmoid colon to the superior border of the rectum at maximum straining (MSR) were measured.

RESULTS

Among 275 patients with sigmoidocele, 251 (91.6%) were female. The mean age was 51.53±12.99 years. We classified 26, 205, and 44 cases as grades I, II, and III, respectively. Patients with more severe sigmoidocele had greater sigmoid colon mobility (RMS: 19.13±8.54 mm, 34.45±14.51 mm, and 48.70±20.05 mm for grades I, II, and III, respectively; p < 0.001) and more pronounced compression of the rectum by the sigmoid colon at maximum straining (MSR: 35.23±8.44 mm, 26.33±13.29 mm, and 15.18±18.00 mm, respectively; p < 0.001). We regrouped the patients based on sigmoid colon alignment. Type L patients had the most severe constipation.

CONCLUSION

Our study presents a novel sigmoidocele classification. The anatomic appearance and location of the herniated sigmoid colon observed using fluoroscopy during defecation may help improve the clinical awareness of ODS caused by sigmoidocele.

The Middle Rectal Artery: Revisited Anatomy and Surgical Implications of a Neglected Blood Vessel

BACKGROUND

Although the middle rectal artery is a relevant anatomical landmark for rectal resection and lateral lymph node dissection, descriptions of this entity are highly divergent.

OBJECTIVE

Dissection, visualization, morphometry, and 3-dimensional reconstruction of the middle rectal artery to facilitate its management in surgery.

DESIGN

Macroscopic dissection, histologic study, morphometric measurements, and virtual modeling.

SETTING

University laboratory of applied surgical anatomy.

PATIENTS

This study includes formalin-fixed hemipelvis specimens (n=37) obtained from body donors (age, 67-97 y).

MAIN OUTCOME MEASURES

The main outcome measures are photo documentation of origin, trajectory, diameter, and branching pattern; immunolabeling of lymphatics; and 3-dimensional reconstruction of the middle rectal artery.

RESULTS

The middle rectal artery was present in 71.4% of body donors (21.4% bilateral, 50% unilateral), originated from the anterior division of the internal iliac artery, and branched either from the internal pudendal artery (45.5%), the inferior gluteal artery (22.7%), the gluteal-pudendal trunk (22.7%), or a trifurcation (9.1%). One to 3 branches of varying diameters (0.5-3.5 mm) entered the mesorectum from the ventrolateral (35.7%), lateral (42.9%), or dorsolateral (21.4%) aspect. The middle rectal artery was accompanied by podoplanin-immunoreactive lymphatic vessels and gave off additional branches (81.8%) to the urogenital pelvic organs. Three-dimensional reconstruction revealed the complex course of the middle rectal artery from the pelvic sidewall through the pelvic nerve plexus and parietal pelvic fascia into the mesorectum.

LIMITATIONS

Findings retrieved from body donors may be prone to age- and fixation-related processes.

CONCLUSIONS

The investigation disclosed the rather high prevalence of the middle rectal artery, its 3-dimensional topographic anatomy, and its proximity to the autonomic pelvic nerves. These features play a role in the surgical management of this blood vessel. The data provide the anatomical rationale for the lateral lymphatic spread of rectal cancer and an anatomical basis for nerve-preserving lateral lymph node dissection.

Exposure of the Middle Rectal Artery and Lateral Ligament of the Rectum Following the Gate Approach during Total Mesorectal Excision

Controversial surgical anatomical landmarks in the deep pelvis can be visualized and identified using current technologies. Performing the gate approach technique during deep lateral dissection for total mesorectal excision facilitates visualization of the pelvic neurovascular structures following simple dissection steps to preserve the pelvic autonomic nerves and avoid accidental vascular injuries. Here, we discuss laparoscopic exposure of an infrequent disposition of the middle rectal artery anterior to the lateral ligament of the rectum while performing the gate approach.

The middle anorectal artery - a systematic review and meta-analysis of 880 patients / 1905 pelvic sides

INTRODUCTION

The middle anorectal artery (MAA) is considered to supply the middle and lower parts of the rectum however its prevalence and point of origin vary across the literature. Clinical importance of the MAA becomes evident in the total mesorectal excision during the colorectal surgery of rectal cancer in both sexes, as well as interventional radiology procedures utilizing the prostatic vasculature in males.

MATERIALS AND METHODS

Major electronic medical databases were investigated for terms pertaining to the MAA and its associated variations. Compatible data regarding the artery's prevalence, laterality, origin, and distribution in both sexes was acquired. The risk of bias within the studies was assessed utilizing the AQUA tool.

RESULTS

In total, 28 works (n=880 patients / 1905 pelvic sides) were included in this systematic review and meta-analysis, and their publication date ranged from 1897 until 2021. The overall pooled prevalence estimate for the MAA was 59.8% of the patients, and 55.2% of the pelvic sides studied. The vessel was identified more frequently in cadaveric pelvic sides evaluations (79.3%). The artery was found bilaterally more often (56.7%), and most commonly originated from the internal pudendal artery (50.3%). Anastomoses between the MAA and the other anorectal arteries were reported in 78.1%.

CONCLUSIONS

The MAA is predominantly a present vessel, with various point of origin. Its direct clinical significance is yet to be discovered in larger study samples, providing more detailed and unified reports of its anatomical features, especially regarding its branches.

OUP accepted manuscript

Background

The relative anatomical understanding of the perirectal fasciae is of paramount importance for the proper performance of total mesorectal excision (TME). This study was to demonstrate the planes of TME and validates the intraoperative findings using cadaveric observations.

Methods

In this combined retrospective and prospective study, bilateral attachment of the rectosacral fascia (RSF) was observed in 28 cadaveric specimens (male, n = 14; female, n = 14). From January 2018 to December 2019, surgical videos of 67 patients who underwent laparoscopic TME at the Affiliated Union Hospital of Fujian Medical University (Fuzhou, China) were reviewed and interpreted with the cadaveric findings.

Results

The RSF (synonym: Waldeyer's fascia) is the end of the pre-hypogastric fascia at the level of S4 and comprises two layers (upper and lower). These two layers provide double fascial protection for the venous sacral plexus. It inserts into the fascia propria of the rectum along a broad horizontal arc that merges anterolaterally in an oblique downward direction until it meets the posterolateral merge of Denonvilliers' fascia at the lateral rectal ligament (LRL). This ligament does not look like a true ligament but is more likely to be a fascial combination that cushions the rectal innervation and middle rectal vessels.

Conclusions

Understanding the lateral attachment of RSF and its contribution to LRL provides invaluable surgical guidance to dissect this critical area. Therefore, lateral dissection is proposed from the anterior to the posterior direction to find the correct plane that guarantees an intact mesorectal envelope to protect the important nearby nerve structures.

Oncologic impact of lateral lymph node metastasis at the distal lateral compartment in locally advanced low rectal cancer after neoadjuvant (chemo)radiotherapy

INTRODUCTION

The frequency and oncologic outcomes of lateral lymph node (LLN) metastasis at the most distal lateral compartment (DLC) among clinical stage II-III low rectal cancer patients treated with neoadjuvant (chemo)radiotherapy (nCRT) are poorly understood. The aim was to investigate the oncologic impact of LLN metastasis in the DLC versus the proximal lateral compartment (PLC).

MATERIALS AND METHODS

Consecutive patients with low rectal cancer treated with nCRT followed by total mesorectal excision and selective LLN dissection including the DLC were analyzed retrospectively. DLC was defined as the area distal to the infra-piriformis foramen on axial MRI images. Size and location of LLN metastasis on MRI, and survival were retrospectively assessed.

RESULTS

Of the 718 patients, 72 (10.0%) had pathological LLN metastasis. Thirty-two (44.4%) had metastasis in the DLC (DLC group), while 40 (55.6%) had metastasis in the PLC without metastasis in the DLC (PLC group). The proportion of ypN2 category tended to be lower in the DLC group (15.6% vs 35.0%, P = 0.105). The median number of metastatic LLN was similar (1 vs. 1, P = 0.691). The median short-axis size of metastatic LLN was smaller in the DLC group than in the PLC group on pre-treatment (P < 0.001) and re-staging (P = 0.004) MRI. By multivariable analysis, LLN metastasis in the DLC was predictive of better disease-free survival (HR, 0.412; 95% CI, 0.159-0.958, P = 0.039).

CONCLUSION

LLN metastasis in the DLC is frequent and has favorable oncologic outcomes after surgical dissection with nCRT.

The middle rectal artery detected by contrast-enhanced magnetic resonance imaging predicts lateral lymph node metastasis in lower rectal cancer

PURPOSE

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.

CONCLUSION

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.

TRIAL REGISTRATION

Trial registration number: retrospectively registered 2126 Trial registration date of registration: August 23, 2019.

Total Mesorectal Excision Technique-Past, Present, and Future

While the treatment of rectal cancer is multimodal, above all, a proper oncological resection is critical. The surgical management of rectal cancer has substantially evolved over the past 100 years, and continues to progress as we seek the best treatment. Rectal cancer was historically an unsurvivable disease, with poor understanding of the embryological planes, lymphatic drainage, and lack of standardized technique. Major improvements in recurrence, survival, and quality of life have resulted from advances in preoperative staging, pathologic assessment, the development and timing of multimodal therapies, and surgical technique. The most significant contribution in advancing rectal cancer care may be the standardization and widespread implementation of total mesorectal excision (TME). The TME, popularized by Professor Heald in the early 1980s as a sharp, meticulous dissection of the tumor and mesorectum with all associated lymph nodes through the avascular embryologic plane, has shown universal reproducible reductions in local recurrence and improvement in disease-free and overall survival. Widespread education and training of surgeons worldwide in the TME have significantly impact outcomes for rectal cancer surgery, and the procedure has become the gold standard for curative resection of rectal cancer. In this article, we discuss the evolution of the standard abdominal approach to the TME, with emphasis on the history, relevant anatomy, standard procedure steps, oncologic outcomes, and technical evolution.

Locally advanced rectal cancer: The past, present, and future

From a series of clinical trials in the last several decades, current treatment paradigms for locally advanced rectal cancer include: (1) preoperative long-course radiotherapy (RT) combined with radiosensitizing chemotherapy; (2) preoperative short-course RT alone followed by adjuvant postoperative chemotherapy; and (3) total neoadjuvant therapy with induction chemotherapy followed by chemoradiotherapy. Other strategies under active investigation in both institutional and cooperative trials include neoadjuvant chemotherapy alone without RT in select patients, total neoadjuvant therapy, watchful waiting after a clinical complete response as an alternative to surgical resection, and the use of different chemotherapeutic and targeted agents. The focus of this review is on established and novel therapeutic strategies for locally advanced rectal cancer.

The 'multilayer' theory of Denonvilliers' fascia: anatomical dissection of cadavers with the aim to improve neurovascular bundle preservation during rectal mobilization

AIM

Denonvilliers' fascia is thought to be a multilayered fascial structure, based on its embryological development with the neurovascular bundle embedded within it. Recently, this theory had been proven histologically and by confocal microscopy in many published articles. However, the literature does not report on how surgeons can identify these structures. We aimed to determine the optimal surgical approach for preserving these critical structures.

METHOD

Eighteen cadavers (13 male/five female) were included and treated according to the ethical considerations stated in the donation consent of our institution. Dissection was performed with the assistance of binocular loupes for better anatomical detail. The compositions of the prerectal fascia and the neurovascular bundle were observed and recorded at different levels of dissection using a high-definition camera.

RESULTS

The theoretical multilayered fascia was found in male specimens as three fascial layers originating from the perineal body, seminal vesicles and posterior bladder neck. The first layer merged posterolaterally and fused with the rectosacral fascia (Waldeyer's fascia). The neurovascular bundle in male specimens was observed piercing the second and third layers, while the first layer acted as a protective cover. Dissection of female specimens demonstrated only one layer in the prerectal space.

CONCLUSION

Intiating anterior rectal mobilization by incising the peritoneum posterior to its reflection seems to be anatomically correct to preserve DVF. However, its applicability may be difficult in a narrow chanllenging pelvis. The lateral rectal ligaments and Waldeyer's fascia should be dissected from their attachments to the proper fascia of the rectum.

Detailed and applied anatomy for improved rectal cancer treatment

Rectal anatomy is one of the most challenging concepts of visceral anatomy, even though currently there are more than 23,000 papers indexed in PubMed regarding this topic. Nonetheless, even though there is a plethora of information meant to assist clinicians to achieve a better practice, there is no universal understanding of its complexity. This in turn increases the morbidity rates due to iatrogenic causes, as mistakes that could be avoided are repeated. For this reason, this review attempts to gather current knowledge regarding the detailed anatomy of the rectum and to organize and present it in a manner that focuses on its clinical implications, not only for the colorectal surgeon, but most importantly for all colorectal cancer-related specialties.

Reappraisal of the lateral rectal ligament: an anatomical study of total mesorectal excision with autonomic nerve preservation

PURPOSE

The term "lateral rectal ligament" in surgery for rectal cancer has caused confusion regarding its true existence and contents. In previous studies, investigators claimed the existence of the ligament and described its topographical features as neurovascular structures and their surrounding connective tissues located at the anterolateral aspect of the distal rectum or the posterolateral aspect of the middle rectum. The purpose of this study is to evaluate the structure of the so-called "lateral rectal ligament" in cadaver dissections.

METHODS

Dissection was performed in nine cadavers (eight males and one female, aged 73 to 94 years) in accordance with typical total mesorectal excision techniques. During dissection, structures related to "the ligament" were examined and images recorded.

RESULTS

At the anterolateral aspect of the distal rectum, the middle rectal artery was noted to be crossing the fusion of Denonvilliers' fascia and the proper rectal fascia. At the posterolateral aspect of the middle rectum, there was a structure which consisted of the rectal nerves running through the fusion of the pelvic fasciae. Although called "ligaments," neither structure contained discrete strong connective tissue fixing the rectum to the pelvic wall.

CONCLUSIONS

The proper rectal fascia and surrounding pelvic fasciae fuse firmly anterolaterally and posterolaterally where neurovascular structures course toward the rectum. During a total mesorectal excision, the surgical dissection plane coincides with the fused part of the fasciae, which had long been considered the "lateral rectal ligament."

Anatomy of the middle rectal artery: a review of the historical literature

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.

Total Mesorectal Excision, an erroneous anatomical term for the gold standard in rectal cancer treatment

In 1986 Professor R J Heald published in The Lancet his new technique which he called Total Mesorectal Excision; today this is the gold standard for the surgical management of rectal cancer. In Total Mesorectal Excision (TME), the mesorectum is the term used to describe all the peri-rectal connective tissue including the posterior sheath of the endopelvic fascia containing the peri-rectal neurovascular structures. However, the mesenterium is a defined structure composed of a double layer of peritoneum which does not include the endopelvic fascia and the lateral rectal stalks, so these should not be included in the term 'mesorectum'. In our globalized medical culture it is important to use anatomic terms approved by the International Federation of Associations of Anatomists, as contained in the Terminologia Anatomica produced by the Federative International Programme for Anatomical Terminology (FIPAT). The term mesorectum is not listed in the Terminologia Anatomica.

Mesorectal excision: Surgical anatomy of the rectum, mesorectum, and pelvic fascia and nerves and clinical relevance

Biologic behavior and management of rectal cancer differ significantly from that of colon cancer. The surgical treatment is challenging since the rectum has dual arterial blood supply and venous drainage, extensive lymphatic drainage and is located in a bony pelvic in close proximity to urogenital and neurovascular structures that are invested with intricate fascial covering. The rectum is encased by fatty lymphovascular tissue (mesorectum) that is surrounded by perirectal fascia that act as barrier to the spread of the cancer and constitute the surgical circumferential margin. Locoregional recurrence after rectal cancer surgery is influenced by tumor-related factors and adequacy of the resection. Local recurrence is associated with incomplete excision of circumferential margin, violation of perirectal fascia, transmesorectal dissection, presence of isolated deposits in the mesorectum and tumor in regional lymph nodes and incomplete lymph node clearance. Hence to eradicate the primary rectal tumor and control regional disease, the rectum, first area of lymph node drainage and surrounding tissue must be completely excised while maintaining an intact fascial envelope around the rectum and preserving surrounding structures. This is achieved with extrafascial dissection and removal of the entire mesorectum including the portion distal to the tumor (total mesorectal excision) within its enveloping fascia as an intact unit. Total mesorectal excision is the standard of care surgical treatment of mid and low rectal cancer and can be performed in conjunction with low anterior resection, abdominoperineal resection, extralevator abdominoperineal resection, and extraregional dissection. To accomplish such a resection, thorough knowledge of the surgical anatomy of the rectum and pelvic structures and fascial planes is paramount.

Ligaments of the Rectum: Anatomical and Surgical Considerations

The ligaments of the rectum have been the subject of controversy for decades. Not only have their contents and components been a source of contention, but also the very existence of these ligaments has been called into question. This article explores the anatomical features of these ligaments with implications for surgical treatment of rectal prolapse, rectal cancer, and resection of the rectum and mesorectum. A theory about the evolution of the lateral rectal ligaments and the mesorectum in humans and higher mammals is also presented.

Laparoscopic-assisted low anterior resection of the rectum--a review of the fascial composition in the pelvic space

INTRODUCTION

Outcomes of rectal cancer treatment depend on the operative technique, and complication rates vary. Complications can occur during mobilization of the rectum, with damage to the ureter, autonomic nerves, and the rectum itself. Frequencies of these complications can be reduced by careful dissection of the correct tissue plane in the pelvic space.

METHODOLOGY

This paper reviews the fascial composition of the rectum for low anterior resection of the rectum. To date, fascial composition of the pelvic space has been considered based on clinical anatomy and histological examination of cadaveric specimens. However, clarification of fascial composition is clearly limited, to a certain extent, in histological examinations compared with clinical anatomy.

CONCLUSIONS

First, some degree of dissociation must exist between the histological examination and clinical anatomy. Second, surgeons should not consider fascia encountered intraoperatively as an artifact. To address these difficult issues, consideration should be made purely from the perspective of clinical anatomy. Originally, the trunk was embryologically regarded as a multi-layered structure (like an onion). Understanding the fascial composition of the abdomen is comparatively easy when approached from this perspective. If this theory is adapted to the pelvic space in order to avoid antilogy, an understanding of the fascial composition of the pelvic space should also be possible. We review previous papers based on this theory.

The anatomy of lateral ligament of the rectum and its role in total mesorectal excision

BACKGROUND

Lateral ligament of the rectum has suffered many diverse descriptions in its existence and composition. This study was undertaken to define the anatomy, nature, content of the lateral ligament of the rectum, and its role in total mesorectal excision.

METHODS

Cadaver dissections were performed on 32 formalin-preserved cadavers.

RESULTS

Bilateral lateral ligament appeared in all 32 cadavers as a bundle of dense connective tissue traversing between rectum and visceral fascia instead of pelvic sidewall. No substantial tissue strand except pelvic splanchnic nerves was found between visceral fascia and parietal fascia at the same level. The middle rectal artery was observed in only 18 of 64 pelvic-halves (28.1%). The constant component of the lateral ligament of the rectum was the rectal branches from the pelvic plexus, whereas the middle rectal artery was almost invisible in lateral ligament of the rectum.

CONCLUSIONS

During total mesorectal excision, it is impossible to reveal the lateral ligament of the rectum in the correct plane between visceral and parietal fascia. The entire rectum may be mobilized without the need for ligating the middle rectal artery. The clinical significance of lateral ligament is that, during lateral dissection, if the dense lateral ligament was identified, then the surgical plane was medial to the visceral fascia and incorrect surgical plane thus entered.

Anatomy of the lateral ligaments of the rectum: A controversial point of view

The existence and composition of the lateral ligaments of the rectum (LLR) are still the subjects of anatomical confusion and surgical misconception up to now. Since Miles proposed abdominoperineal excision as radical surgery for rectal cancer, the identification by “hooking them on the finger” has been accepted by many surgeons with no doubt; clamping, dividing and ligating are considered to be essential procedures in mobilization of the rectum in many surgical textbooks. But in cadaveric studies, many anatomists could not find LLR described by the textbooks, and more and more surgeons also failed to find LLR during the proctectomy according to the principle of total mesorectal excision. The anatomy of LLR has diverse descriptions in literatures. According to our clinical observations, the traditional anatomical structures of LLR do exist; LLR are constant dense connective bundles which are located in either lateral side of the lower part of the rectum, run between rectal visceral fascia and pelvic parietal fascia above the levator ani, and covered by superior fascia of pelvic diaphragm. They are pathways of blood vessels and nerve fibers toward the rectum and lymphatic vessels from the lower rectum toward the iliac lymph nodes.

Perirectal fascia and spaces: annular distribution pattern around the mesorectum

PURPOSE

In view of debate on the optimal surgical planes for total mesorectal excision, this study was designed to explore the regional anatomy of the perirectal fascia and spaces.

METHODS

Twenty-one cadavers (15 male and 6 female) were embalmed and their vessels visualized by injection with color dye. From the cadavers, 30 hemipelves and 6 three-quarter pelves were harvested. The perirectal fascia and spaces and the pelvic autonomic nerves were dissected and examined.

RESULTS

Three tissue layers were dissected from the inside to the periphery: the proper rectal fascia enveloping the mesorectum, the presacral fascia, and the piriformis fascia fused with the sacral periosteum. The mesorectum comprised 2 parts: posterior, with the classical posterolateral fat covered by the proper rectal fascia; and anterior, with the anterior fat covered by the posterior layer of Denonvilliers fascia. Extending anteriorly to the anterior layer of Denonvilliers fascia, the presacral fascia bisected the space between the mesorectum and the piriformis fascia into the retrorectal space and the presacral space. The retrorectal space extended cranially to the left Toldt's space, anterior to the space between the 2 layers of Denonvilliers fascia.

CONCLUSIONS

From the inside to the periphery, the proper rectal fascia, the presacral fascia, and the muscular fascia are distributed in an annular pattern around the mesorectum. The presacral fascia divides the perirectal space into 2 annular parts: the central retrorectal space and the peripheral presacral space. The retrorectal space is the ideal surgical plane for the total mesorectal excision.

The angiographic anatomy of the small arteries and their collaterals in colorectal resections: some insights into anastomotic perfusion

OBJECTIVE

The aim of this study was to examine by screening angiography the anatomy of the small arteries and their collaterals in colorectal resections in order to identify factors that might be implicated in anastomotic leak.

SUMMARY BACKGROUND DATA

Anastomotic leak is more frequent following low anterior resection. Vascular compromise is frequently implicated but poorly understood as a mechanism.

METHODS

High definition screening angiography was performed on 17 colorectal resection specimens.

RESULTS

(1) The small arteries of the colon (the vasa recta that arise from the marginal artery) show variability in their spacing and in their collaterals based on their anatomical positions. At the splenic flexure and the proximal and mid descending colons, the vasa recta are spaced 2-cm apart and have few collaterals. At the right, transverse, distal descending and sigmoid colons, the vasa recta are spaced <1 cm apart and have more extensive collaterals. (2) The small arteries of the rectum are spaced <1 cm apart and also show variability in their collaterals based on their anatomical level. In the mid-to-upper rectum there are good collaterals between the small arteries within the mesorectum based upon the bifurcation of the superior rectal artery and its main branches. In the lower rectum, however, there are only a few and very variable intramural collaterals between the small arteries.

CONCLUSIONS

Based on these findings, unrecognized disruption of small artery collaterals during colorectal resection might be implicated in anastomotic leak and in particular might explain the higher leak rate in low anterior resection.

The anatomic basis of total mesorectal excision

BACKGROUND

Total mesorectal excision is considered the gold standard for rectal cancer surgery, but the anatomic descriptions and nomenclatures that are used are hardly clear and sometimes are contradictory. The aim of this study was to clarify the delimitation of the mesorectum and anatomic landmarks of the correct surgical plane for total mesorectal excision.

METHODS

Cadaveric dissections were performed on 32 pelvises.

RESULTS

The pelvic fasciae around the rectum can be divided into visceral fascia, vesicohypogastric fascia, and parietal fascia. The lateral ligament is the dense connective tissue between the rectum and visceral fascia instead of the pelvic sidewall. There are 2 different fascial envelopes around the rectum. The diffusion type of pelvic plexus is difficult to separate from the visceral fascia.

CONCLUSIONS

The autonomic nerves and lateral rectal ligament can be distinguished as the landmark to judge the different planes. The correct surgical plane of posterior dissection is conducted between the visceral fascia and parietal fascia, and anterolateral dissection is conducted between the vesicohypogastric fascia and parietal fascia.

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.

Vascular anatomy of the rectal stump after total mesorectal excision

PURPOSE

For many years, poor vascularization of the short rectal stump has been considered the main cause of leakage. The purpose of this study was to evaluate the vascularization of the rectal stump after total mesorectal excision.

METHODS

We studied the iliac vascularization on 28 volunteers with healthy rectum to have an anatomic basis. Then, we studied the vascularization of the rectal stumps after total mesorectal excision by using angio computed tomography at seven and three months after operating on 22 patients; we validated this technique by studying the vascularization using angio computed tomography in 18 rectal specimens from cadavers.

RESULTS

Both in healthy rectums and in rectal stumps after total mesorectal excision, there is good vascularization sustained by middle and inferior rectal arteries. The former is more important and frequent as described in previous literature.

CONCLUSIONS

The vascularization of the short rectal stump is generally well represented even after total mesorectal excision.

Anatomic basis of sharp pelvic dissection for curative resection of rectal cancer

The optimal goals in the surgical treatment of rectal cancer are curative resection, anal sphincter preservation, and preservation of sexual and voiding functions. The quality of complete resection of rectal cancer and the surrounding mesorectum can determine the prognosis of patients and their quality of life. With the emergence of total mesorectal excision in the field of rectal cancer surgery, anatomical sharp pelvic dissection has been emphasized to achieve these therapeutic goals. In the past, the rates of local recurrence and sexual/voiding dysfunction have been high. However, with sharp pelvic dissection based on the pelvic anatomy, local recurrence has decreased to less than 10%, and the preservation rate of sexual and voiding function is high. Improved surgical techniques have created much interest in the surgical anatomy related to curative rectal cancer surgery, with particular focus on the fascial planes and nerve plexuses and their relationship to the surgical planes of dissection. A complete understanding of rectum anatomy and the adjacent pelvic organs are essential for colorectal surgeons who want optimal oncologic outcomes and safety in the surgical treatment of rectal cancer.

The location and contents of the lateral ligaments of the rectum: a study in human soft cadavers

PURPOSE

This study was designed to identify the location of the lateral ligaments of the rectum and to reveal its contents.

METHODS

From 18 human soft cadavers (9 males), 18 pelves were sagittally sectioned into 36 hemipelvic specimens affording good anatomic view of the lateral aspect of the rectum. All of them were dissected and mobilized by using sharp technique under direct vision by one surgeon to avoid confounding factor. The lateral ligaments of the rectum were identified and the distances from the center of its pelvic attachment to the promontory of sacrum and coccyx were measured. After measurement, they were transected and brought for histologic examination.

RESULTS

In 36 hemipelvic specimens, 18 lateral ligaments of the rectum were found on the right side of the rectum and 18 were found on the left side. One cadaver had no lateral ligament on the right side and another had two lateral ligaments on the right side 3-cm apart. The location of the lateral ligaments was posterolateral to the rectum. The distance from the lateral ligament to sacral promontory on right side was 8.14 +/- 1.82 cm (mean +/- standard deviation) and 8.14 +/- 1.22 cm on left side. The distances from the lateral ligament to coccyx on the right and left sides were 5.12 +/- 1.4 cm and 4.88 +/- 1.29 cm, respectively. The content of the lateral ligaments of the rectum consisted of loose connective tissue with cluster of small nerves. No artery was detected in all specimens. The small arterioles and venules were discovered in only four specimens.

CONCLUSIONS

The lateral ligaments of the rectum were located at posterolateral side of the rectum. They were closer to the coccyx than to the sacral promontory. Its component was loose connective tissue containing multiple small nerves. There was no artery found in any lateral ligaments by histologic study. Small arterioles and venules were detected 11 percent.

Terminologia Anatomica versus unofficial descriptions and nomenclature of the fasciae and ligaments of the female pelvis: a dissection-based comparative study

OBJECTIVE

The aims of this study were: (1) to define and classify those connective structures of the female pelvis that are of potential clinical interest, (2) to evaluate the adequacy of the Terminologia Anatomica (official nomenclature) and (3) to establish a correspondence between the official nomenclature and the most commonly used terms.

STUDY DESIGN

The results of 30 macroscopic and laparoscopic dissections of fresh cadavers with and without vessel injection of colored latex solutions were compared with the descriptions and definitions in the Terminologia Anatomica and the most frequently cited English and non-English literature from 1890 to 2003.

RESULTS

We identified 3 groups of fasciae, parietal pelvic fascia, visceral pelvic fascia, and extraserosal pelvic fascia, which could be divided into diverse clinically relevant anatomical structures characterized by different locations, spatial orientation, and consistency. These structures differed considerably with regard to number and nomenclature from those described in the Terminologia Anatomica and part of the literature.

CONCLUSION

Our results suggest that the official terminology applied to the connective structures of the female pelvis could be profitably revised and expanded. We offer a complete description of these structures and suggest a classification that may be useful for teaching and clinical purposes.