Perirectal Fascial Anatomy

Background The architecture of perirectal fasciae is complex as mirrored by different anatomical concepts. Objective This study aimed to perform a comprehensive visualization of perirectal fasciae to facilitate strategies of rectal surgery such as total mesorectal excision, intersphincteric resection, and transanal total mesorectal excision. Design Macroscopic dissection and histologic studies of perirectal fasciae and autonomic pelvic nerves were performed. Settings This study was conducted in a university laboratory of macroscopic and microscopic anatomy. Patients Thirteen (5 female) pelvic specimens were obtained from body donors (67-92 years of age). Main outcome measures The primary outcomes measured were the photodocumentation of perirectal fasciae, spaces and fusion zones, and histologic and immunohistochemical analysis of key structures. Results The retrorectal space is a mesofascial interface between the mesorectal fascia and the parietal pelvic fascia. The parietal pelvic fascia is composed of 2 lamellae ensheathing the autonomic pelvic nerves. The outer lamella of the parietal pelvic fascia and the presacral fascia confine the presacral space. The presacral fascia covers the median sacral blood vessels. Approximately at the fourth sacral vertebra, all fascial layers fuse in the midline and are densely connected to the posterior rectal wall via the rectosacral ligament. The parietal pelvic fascia fuses with the pubococcygeal and longitudinal rectal muscles at the anorectal junction. Anterolaterally, the neurovascular bundles are closely related to this fascial fusion zone and the rectogenital septum. Limitations Because of the increased age of the body donors, the findings may be subjected to age-related degenerative processes. Conclusions The 2 lamellae of the parietal pelvic fascia and the fascial fusion zones are key structures of perirectal anatomy. For autonomic nerve preservation, the recognition of the inner lamella of the parietal pelvic fascia is crucial. To avoid inadvertent rectal perforation or accidental presacral dissection, the rectosacral ligament must be identified and transected for complete rectal mobilization. See Video Abstract at http://links.lww.com/DCR/B389. ANATOMIA FASCIAL PERIRRECTAL: NUEVOS CONCEPTOS SOBRE UN ANTIGUO PROBLEMA: La arquitectura de las fascias perirrectales es compleja, reflejada por distintos conceptos anatomicos.Integracion de conceptos sobre las fascias perirrectales para facilitar las estrategias de cirugia rectal, como la escision mesorrectal total, la reseccion interesfinterica y la escision mesorrectal total transanal.Diseccion macroscopica y estudios histologicos de fascias perirrectales y nervios pelvicos autonomicos.Laboratorio universitario de anatomia macroscopica y microscopica.Trece (5 mujeres) muestras pelvicas obtenidas de donantes de cuerpo (67-92 anos).Foto documentacion de fascias perirrectales, espacios y zonas de fusion, analisis histologico e inmunohistoquimico de estructuras claves.El espacio retrorectal es una interfaz mesofascial entre la fascia mesorrectal y la fascia pelvica parietal. Este ultimo se compone de dos laminas que envuelven los nervios pelvicos autonomicos. La lamina externa de la fascia pelvica parietal y la fascia presacra definen el espacio presacro. La fascia presacra cubre los vasos sanguineos sacros medianos. Aproximadamente en la cuarta vertebra sacra, todas las capas fasciales se unen en la linea media y estan densamente conectadas a la pared rectal posterior a traves del ligamento rectosacro. La fascia pelvica parietal se une con los musculos rectal pubococcigeo y longitudinal en la union anorrectal. Anterolateralmente, los haces neurovasculares estan estrechamente relacionados con esta zona de fusion fascial y el tabique rectogenital.Debido al aumento de la edad de los donantes de cuerpos, los hallazgos pueden estar sujetos a procesos degenerativos relacionados con la edad.Las dos laminas de la fascia pelvica parietal y las zonas de fusion fascial son estructuras claves de la anatomia perirrectal. Para la preservacion del nervio autonomo de nervios pelvicos autonomicos, el reconocimiento de la lamina interna de la fascia pelvica parietal es importante. Para evitar la perforacion rectal inadvertida o la diseccion presacra accidental, el ligamento rectosacro debe ser identificado y seccionado para una movilizacion rectal completa. Consulte Video Resumen en http://links.lww.com/DCR/B389.