Denonvilliers' fascia in men: a sheet plastination and confocal microscopy study of the prerectal space and the presence of an optimal anterior plane when mobilizing the rectum for cancer

Visualization of the dentogingival junction using micro-plastination technique

Plastination has revolutionized the field of anatomy and research by providing biosecurity and enabling the long-term preservation of biological material, ranging from entire bodies to individual organs and even micron sections. The dentogingival junction (DGJ) consists of both epithelial and connective tissues that are closely related to the tooth's mineralized tissues. Cutting-grinding techniques are commonly used to visualize DGJ histology. These techniques exclude enamel from preparations and focus on visualizing hard or soft tissues. To improve the micro-anatomical and histological study of this region, we applied micro-plastination technique to obtain micro-thin slices below 150 μm thick from human and animal samples. The DGJ microanatomy was visualized by applying histological stains to the micro-plastinated slices, highlighting the technique's endogenous autofluorescence capacity identifying periodontal tissues, including dentin, enamel, cementoenamel junction, dentinal tubules, connective tissue, and collagen. Based on our results, we confirm that micro-plastination is a useful technique for visualizing anatomical regions that are difficult to access, such as the DGJ. Micro-plastination can be used as an alternative technique, providing a new approach for its application in anatomical and morphological research protocols.

Preservation versus resection of Denonvilliers' fascia in total mesorectal excision for male rectal cancer: follow-up analysis of the randomized PUF-01 trial

Traditional total mesorectal excision (TME) for rectal cancer requires partial resection of Denonvilliers' fascia (DVF), which leads to injury of pelvic autonomic nerve and postoperative urogenital dysfunction. It is still unclear whether entire preservation of DVF has better urogenital function and comparable oncological outcomes. We conducted a randomized clinical trial to investigate the superiority of DVF preservation over resection (NCT02435758). A total of 262 eligible male patients were randomized to Laparoscopic TME with DVF preservation (L-DVF-P group) or resection procedures (L-DVF-R group), 242 of which completed the study, including 122 cases of L-DVF-P and 120 cases of L-DVF-R. The initial analysis of the primary outcomes of urogenital function has previously been reported. Here, the updated analysis and secondary outcomes including 3-year survival (OS), 3-year disease-free survival (DFS), and recurrence rate between the two groups are reported for the modified intention-to-treat analysis, revealing no significant difference. In conclusion, L-DVF-P reveals better postoperative urogenital function and comparable oncological outcomes for male rectal cancer patients.

Navigating surgical anatomy of the Denonvilliers’ fascia and dissection planes of the anterior mesorectum with a cadaveric simulation model

Anterior dissection of the rectum in the male pelvis represents one of the most complex phases of total meso-rectal excision. However, the possible existence of different anatomical planes is controversial and the exact anatomical topography of Denonvilliers’ fascia is still debated. The aim of the study is to accurately define in a cadaveric simulation model the existence and boundaries of Denonvilliers’ fascia, identifying the anatomical planes suitable for surgical dissection. The pelvises of 31 formalin-preserved male cadavers were dissected. Careful and detailed dissection was carried out to visualize the anatomical structures and the potential dissection planes, simulating an anterior meso-rectum dissection. Denonvilliers’ fascia was identified in 100% of the pelvises, as a single-layer fascia that originates from the peritoneal reflection and descends until its firm adhesion to the prostate capsule. The fascia divides the space providing an anterior and a posterior plane. Anteriorly to the fascia, during the caudal dissection, its firm adhesion to the prostate capsule forces to section it sharply. The cadaveric simulation model allowed an accurate description of Denonvilliers’ fascia, defining several planes for anterior dissection of the meso-rectum.

How Useful Is Endoscopic Ultrasound in Differentiating T3/T4a T Stage of Colorectal Cancer: A Prospective Study

Objective

Endoscopic ultrasound (EUS) is an established method for staging of colorectal cancer. Nevertheless, prior assessments of its T stage accuracy have been limited, particularly ambiguity in assessed T3 and T4a stage. This study was to characterize the EUS image features and pay attention to distinguish T3 from T4a T stage.

Methods

A total of 638 patients who prospectively underwent colorectal EUS were recorded. The final diagnoses were compared with the concurrent or follow-up histopathology. Univariate and multivariate logistic regressions were used to assess variation in diagnostic performance with case attributes.

Results

The accuracies of EUS in classifying colorectal cancer for overall, T1, T2, T3, and T4a stages are 73.04, 62.32, 67.46, 71.26, and 83.52%, respectively. With attention to EUS image features, the lesion penetrates the entire wall and locates below the seminal vesicles or cervix is T3 stage. If the lesion locates above clearly-defined space between the anterior rectal wall and the posterior surface of the seminal vesicles or cervix, we identify as T4a stage; However, when located above seminal vesicles or cervix but on the posterior wall of the rectum, the lesion still considers as T3 stage. The tumor location and histological type are associated with inaccuracy T stage.

Conclusions

EUS provides reliable diagnostic accuracy in the colorectal cancer stage. The seminal vesicles and cervix are the important markers to predict infiltration depth for T3/T4a stage. Furthermore, the tumor location, histological type, and EUS image features for each tumor T stage should warrant attention.

Denonvilliers’ fascia acts as the fulcrum and hammock for continence after radical prostatectomy

Background

Radical prostatectomy (RP) is the primary treatment of localized prostate cancer. Immediate urinary incontinence post-RP was still common and depressing without specific reason.

Methods

A multicenter cohort of 154 consecutive patients from 2018 to 2020, who was diagnosed with localized prostate cancer underwent either modified mini-incision retropubic radical prostatectomy (Mmi-RRP) or laparoscopic radical prostatectomy (LRP) or robotic-assisted radical prostatectomy (RARP). Seventy-two patients with Denonvilliers’ fascia (DF) spared were included in DFS (Denonvilliers’ fascia sparing) group. Whereas eighty-two patients with DF completely or partially dissected were set as Group Control. The primary outcome was immediate continence (ImC). Continuous data and categorical data were analyzed with t-test and Chi-square test, respectively. Odds ratios (ORs) were calculated with logistic regression.

Results

Urinary continence of Group DFS was significantly better than that of Group Control at each time point within one year after operation. Incidence rate of continence in Group DFS and Group Control were 83.3% vs 13.4% (P < 0.01) for ImC, 90.3% vs 30.5% (P < 0.01) at 3 months, 91.7% vs 64.6% (P < 0.01) at 6 months, and 93.1% vs 80.5% (P = 0.02) at 1 year after operation, respectively. Positive surgical margin (PSM) showed no significant difference (20.8% vs 20.7%, P = 1.0). In multivariate analysis, DFS showed importance for ImC post RP (OR = 26.4, P < 0.01).

Conclusions

Denonvilliers’ fascia acted as the fulcrum and hammock for continence post RP. Preservation of DF contributed to better continence after RP without increase of PSM.

Trail registration Our research was conducted retrospectively and approved by the ethical committees of Minhang Hospital, but not registered.

Three-dimensional anatomy of the Denonvilliers' fascia after micro-CT reconstruction

An understanding of the anatomy of the Denonvilliers’ fascia is essential for successful surgical outcomes for patients with rectal cancer in the mid- to lower regions, especially near the seminal vesicles and prostate in males. Whether the correct surgical plane during a total mesorectal excision should be anterior or posterior to the Denonvilliers’ fascia is currently under debate. This study aimed to investigate the Denonvilliers’ fascia using micro-computed tomography (micro-CT) to acquire three-dimensional images nondestructively for assessments of the relationship between the Denonvilliers’ fascia, the mesorectal fascia, and neurovascular bundles to elucidate the correct anterior total mesorectal excision plane. Eight specimens were obtained bilaterally from four fresh human cadavers. Four specimens were stained with phosphotungstic acid to visualize the soft tissue, and micro-CT images were obtained; the other four specimens were stained with Masson’s trichrome to visualize connective tissue. Micro-CT images corroborate that the Denonvilliers’ fascia consists of a multilayered structure that separates the rectum from the seminal vesicles and the prostate. Specimens stained with Masson’s trichrome showed that the urogenital neurovascular bundle located at the posterolateral corner of the prostate is separated from the mesorectum by the Denonvilliers’ fascia. For the preservation of autonomic nerves necessary for urogenital function and optimal oncologic outcomes in patients with rectal cancer, a successful mesorectal excision requires a dissection plane posterior to the Denonvilliers’ fascia.

Positional relationship between the lateral border of Denonvilliers' fascia and pelvic plexus

Denonvilliers' fascia is an important landmark of the dissection layer during prostate or rectal surgeries. However, there are few reports on its lateral extension. This anatomical study aimed to define the lateral border of Denonvilliers' fascia and use it as an anatomical landmark to identify the origin and distribution of the nerve branches of the pelvic plexus. We investigated the lateral extent and position of the lateral border of Denonvilliers' fascia through macroscopic examination of 12 pelvic halves from eight cadavers and histological examination of two cadavers. The Denonvilliers' fascia extended laterally to be attached to the pelvic plexus on the lateral border. The origins of nerve branches from the pelvic plexus to the pelvic organs, except the rectum, were located anterior or anterosuperior to the lateral border of Denonvilliers' fascia. The origins of nerve branches to the prostate were mainly anterior to the lateral border of Denonvilliers' fascia; however, in 3/12 pelvic halves, the nerve branches originated in the region posteroinferior to the lateral border of Denonvilliers' fascia. The attachment point of Denonvilliers' fascia to the prostate was more superior in these three pelvic halves (distance from the top point of the posterior surface of the prostate to the attachment point, 5.6 ± 1.9 mm) than that in the other nine pelvic halves (10.1 ± 3.6 mm). The lateral border of Denonvilliers' fascia is closely related to the pelvic plexus, suggesting its usefulness as an anatomical landmark to identify the origin of nerve branches from the pelvic plexus.

Surgical Anatomy of the Rectovaginal Space: Does a Standalone Rectovaginal Septum or Denonvilliers Fascia Exist in Women?

BACKGROUND

Below the anterior peritoneal reflection, the anterior rectal wall and mesorectum are separated from the posterior vaginal wall by a virtual rectovaginal space. In this space, the description of a specific and independent rectovaginal septum as a female counterpart of Denonvilliers fascia has been the subject of debate over the years.

OBJECTIVE

The aim of this study is to perform an accurate anatomical study of the rectovaginal area in a cadaveric simulation model of total mesorectal excision to evaluate the possible structures and the dissection planes contained within the rectovaginal space.

DESIGN AND SETTING

This is a cadaveric study performed at the University of Valencia.

PATIENTS

The pelvises of 25 formalin-preserved female cadavers were dissected. All the included specimens were sectioned in a midsagittal plane, at the level of the middle axis of the anal canal.

MAIN OUTCOME MEASURES

Careful and detailed dissection was performed to visualize the anatomical structures and potential dissection planes during anterior mesorectal dissection in cadavers. Histological sections were made of the posterior vaginal wall.

RESULTS

The rectovaginal space contains loose areolar tissue that allows an easy dissection plane distally. A distinct and independent rectovaginal fascia or septum is not present. The existence of 3 layers fused together in the posterior vaginal wall can be identified more or less precisely because of their different coloration. The histological study confirms this macroscopic arrangement of the posterior vaginal wall in 3 layers: the mucosa, the muscular, and the adventitia. An independent rectovaginal septum can be generated only with a splitting of the adventitia.

LIMITATIONS

The cadaveric pelvic specimens of the oldest donors might have had age-related degeneration.

CONCLUSIONS

The present anatomical study has shown only a plane of loose areolar tissue between the rectal and vaginal wall. We can conclude that there is no independent fascia or septum in the rectovaginal space. See Video Abstract at http://links.lww.com/DCR/B456. ANATOMÍA QUIRÚRGICA DEL ESPACIO RECTOVAGINAL: ¿EXISTE UN TABIQUE RECTOVAGINAL INDEPENDIENTE O UNA FASCIA DE DENONVILLIERS EN LAS MUJERES: Debajo del reflejo peritoneal anterior, la pared rectal anterior y el mesorrecto están separados de la pared vaginal posterior por un espacio rectovaginal virtual. En este espacio, la descripción de un tabique rectovaginal independiente específico como contraparte femenina de la fascia de Denonvilliers ha sido objeto de debate a lo largo de los años.Realizar un estudio anatómico preciso del área rectovaginal en un modelo de simulación cadavérica de escisión mesorrectal total, con el fin de evaluar las posibles estructuras y los planos de disección contenidos en el espacio rectovaginal.estudio cadavérico realizado en la Universidad de Valencia.Se disecaron las pelvis de 25 cadáveres femeninos conservados en formalina. Todas las muestras incluidas fueron seccionadas en un plano medio sagital, a la altura del eje medio del canal anal.Se llevó a cabo una disección cuidadosa y detallada para visualizar las estructuras anatómicas y los posibles planos de disección durante la disección mesorrectal anterior en cadáveres. Se realizaron cortes histológicos de la pared vaginal posterior.El espacio rectovaginal contiene tejido areolar laxo que permite un plano de disección fácil distalmente. No hay fascia o tabique rectovaginal distinto e independiente. La existencia de tres capas fusionadas en la pared vaginal posterior puede identificarse con mayor o menor precisión debido a su diferente coloración. El estudio histológico confirma esta disposición macroscópica de la pared vaginal posterior en tres capas: la mucosa, la muscular y la adventicia. Un tabique rectovaginal independiente solo se puede generar con una división de la adventicia.Las muestras pélvicas de cadáveres de los donantes más antiguos pueden haber tenido degeneración relacionada con la edad.El estudio anatómico actual solo ha mostrado un plano de tejido areolar laxo entre la pared rectal y vaginal. Podemos concluir que no hay fascia o tabique independiente en el espacio rectovaginal. Consulte Video Resumen en http://links.lww.com/DCR/B456. (Traducción-Dr. Adrian Ortega).

Robot-assisted anorectal pull-through for anorectal malformations with rectourethral and rectovesical fistula: feasibility and short-term outcome

BACKGROUND

Multiple structures in the anorectal area are closely related to defecation, voiding and sexual function. Although laparoscopic-assisted anorectal pull-through is widely accepted as a minimally invasive surgical technique, controversy still exists for ARMs with rectourethral fistulas. Intraoperative injuries more or less involve the perirectal sphincters and neurovascular tissue.

METHODS

Seventeen selected infants with ARMs underwent robot-assisted anorectal pull-through (RAARP) between October 2016 and January 2018. The application of nerve- and sphincter-sparing technique in RAARP was detailed. The feasibility and early outcomes were evaluated.

RESULTS

All procedures were completed without conversion. The robotic system facilitated clear dissections between different anatomical layers. Under direct vision, the fistula was easier to repair, and the rectal pouch was precisely placed in the center of the striated muscle complex. During the follow-up of 11.6 months, 13 patients resumed normal defecation. The other four children experienced mild constipation or fecal incontinence. Their continence and defecation functions showed favorable evolution.

CONCLUSION

RAARP is a safe and effective alternative for the treatment of ARMs, which provides an advantage in further minimizing the injury to perirectal nerves and sphincters.

Optimal Complete Rectum Mobilization Focused on the Anatomy of the Pelvic Fascia and Autonomic Nerves: 30 Years of Experience at Severance Hospital

The primary goal of surgery for rectal cancer is to achieve an oncologically safe resection, i.e., a radical resection with a sufficient safe margin. Total mesorectal excision has been introduced for radical surgery of rectal cancer and has yielded greatly improved oncologic outcomes in terms of local recurrence and cancer-specific survival. Along with oncologic outcomes, functional outcomes, such as voiding and sexual function, have also been emphasized in patients undergoing rectal cancer surgery to improve quality of life. Intraoperative nerve damage or combined excision is the primary reason for sexual and urinary dysfunction. In the past, these forms of damage could be attributed to the lack of anatomical knowledge and poor visualization of the pelvic autonomic nerve. With the adoption of minimally invasive surgery, visualization of nerve structure and meticulous dissection for the mesorectum are now possible. As the leading hospital employing this technique, we have adopted minimally invasive platforms (laparoscopy, robot-assisted surgery) in the field of rectal cancer surgery and standardized this technique globally. Here, we review a standardized technique for rectal cancer surgery based on our experience at Severance Hospital, suggest some practical technical tips, and discuss a couple of debatable issues in this field.

Review of Denonvilliers' fascia: the controversies and consensuses

The Denonvilliers' fascia (DVF) plays an important role in rectal surgery because of its anatomic position and its relationship to the surrounding organs. It affects the surgical plane anterior to the rectum in the procedure of total mesorectal excision (TME). Anatomical and embryological studies have helped us to understand this structure to some extent, but many controversies remain. In terms of its embryonical origin, there are three mainstream hypotheses: peritoneal fusion of the embryonic cul-de-sac, condensation of embryonic mesenchyme, and mechanical pressure. Regarding its architecture, the DVF may be a single, two, or multiple layers, or a composite single-layer structure. In women, most authors deem that this structure does exist but they are willing to call it the rectovaginal septum rather than the DVF. Operating behind the DVF is supported by most surgeons. This article will review those mainstream studies and opinions on the DVF and combine them with what we have observed during surgery to discuss those controversies and consensuses mentioned above. We hope this review may help young colorectal surgeons to have a better understanding of the DVF and provide a platform from which to guide future scientific research.

An ossifying bridge - on the structural continuity between the Achilles tendon and the plantar fascia

Highly regular aligned trabeculae are found in the superficial posterior and inferior calcaneus appearing to connect the Achilles tendon (AT) to the plantar fascia (PF) in a bridge-like manner. This provides a morphological basis for the stretching-based heel pain treatment. However, the continuity of collagen fibres between the AT and the PF remains debated controversially to date. The given study morphologically investigated the AT-calcaneus-PF complex using histology and plastination. Moreover, the AT-calcaneus-PF complex was biomechanically mapped based on 13 sub-regions with a total of 76 tested samples. Regular calcaneal trabeculae were surrounded by tendon-like collagen fibre bundles and adipocytes. The orientation of calcaneal trabeculae was further closely related to the course of the PF collagen fibre bundles. The pooled biomechanical analysis revealed low elastic moduli (minimum = 4 MPa) and ultimate tensile strengths of the decalcified calcaneal samples (minimum = 0.4 MPa) and the calcaneal periostea (minimum = 2 MPa) and high respective values (elastic modulus maximum of 144 MPa; ultimate tensile strength maximum of 29 MPa) for the PF samples compared to the other sub-regions. This study provides structural evidence for a morphological connection between the AT and PF via the highly aligned calcaneal trabeculae of the posterior calcaneus. The AT-calcaneus-PF complex was biomechanically mapped to allow for an assessment of its site-dependent mechanical characteristics.

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.

Fibrous configuration of the fascia iliaca compartment: An epoxy sheet plastination and confocal microscopy study

Background and Objectives: The underlying anatomical mechanism of the ultrasound-guided fascia iliaca compartment (FIC) block for anaesthesia and analgesia in the lower limb has not been illuminated and numerous variations were attempted to achieve an optimal needle placement. This study aimed to define the fibrous configuration of the FIC. Methods: A total of 46 adult cadavers were studied using dissection, latex injection, epoxy sheet plastination and confocal microscopy. Results: (1) The fascia iliaca originated from the peripheral fascicular aponeurotic sheet of the iliopsoas. (2) The FIC was a funnel-shaped adipose space between the fascia iliaca and the epimysium of the iliopsoas, had a superior and an inferior opening and contained the femoral and lateral femoral cutaneous nerves but not obturator nerve. (3) The estimated volume of the FIC in the cadavers was about 23 mls, of which about one third was below the level of the anterior superior iliac spine. Conclusions: This study revealed that the fascia iliaca was aponeurotic and may be less permeable for the local anesthetics. Conclusions: The FIC contained only the femoral and lateral femoral cutaneous nerves and communicated with the extraperitoneal space and femoral triangle adipose space via its superior and inferior opening, respectively.

Fine architecture of the fascial planes around the lateral femoral cutaneous nerve at its pelvic exit: an epoxy sheet plastination and confocal microscopy study

OBJECTIVE

Meralgia paresthetica is commonly caused by mechanical entrapment of the lateral femoral cutaneous nerve (LFCN). The entrapment often occurs at the site where the nerve exits the pelvis. Its optimal surgical management remains to be established, partly because the fine architecture of the fascial planes around the LFCN has not been elucidated. The aim of this study was to define the fascial configuration around the LFCN at its pelvic exit.

METHODS

Thirty-six cadavers (18 female, 18 male; age range 38-97 years) were used for dissection (57 sides of 30 cadavers) and sheet plastination and confocal microscopy (2 transverse and 4 sagittal sets of slices from 6 cadavers). Thirty-four healthy volunteers (19 female, 15 male; age range 20-62 years) were examined with ultrasonography.

RESULTS

The LFCN exited the pelvis via a tendinous canal within the internal oblique-iliac fascia septum and then ran in an adipose compartment between the sartorius and iliolata ligaments inferior to the anterior superior iliac spine (ASIS). The iliolata ligaments newly defined and termed in this study were 2-3 curtain strip-like structures which attached to the ASIS superiorly, were interwoven with the fascia lata inferomedially, and continued laterally as skin ligaments anchoring to the skin. Between the sartorius and tensor fasciae latae, the LFCN ran in a longitudinal ligamental canal bordered by the iliolata ligaments.

CONCLUSIONS

This study demonstrated that 1) the pelvic exit of the LFCN is within the internal oblique aponeurosis and 2) the iliolata ligaments form the part of the fascia lata over the LFCN and upper sartorius. These results indicate that the internal oblique-iliac fascia septum and iliolata ligaments may make the LFCN susceptible to mechanical entrapment near the ASIS. To surgically decompress the LFCN, it may be necessary to incise the oblique aponeurosis and iliac fascia medial to the LFCN tendinous canal and to free the iliolata ligaments from the ASIS.