Endopelvic Fascia

The endopelvic fascia is a continuous layer of connective tissue that lines the pelvic cavity and supports the pelvic organs. It forms a critical interface between the pelvic peritoneum and underlying muscular and visceral structures, integrating the structural framework of the bladder, uterus, vagina, rectum, and surrounding muscles. Unlike superficial fascia, the endopelvic fascia is deep, dense, and specialized to bear mechanical load, distribute intra-abdominal pressure, and stabilize pelvic viscera during dynamic functions like urination, defecation, and childbirth. It is essential for pelvic floor function, and its weakening or disruption is a common cause of pelvic organ prolapse.

Structure

The endopelvic fascia is composed of collagen, elastin, fibroblasts, and extracellular matrix proteins. It forms a three-dimensional meshwork that varies in thickness, density, and fiber orientation depending on location. This fascial sheet is anchored superiorly to the parietal pelvic fascia, which lines the walls of the pelvic cavity, and extends inferiorly to invest and support pelvic viscera.

Types of Endopelvic Fascia

• Parietal Endopelvic Fascia: Covers the pelvic muscles (levator ani, obturator internus, piriformis) and lines the pelvic walls
• Visceral Endopelvic Fascia: Surrounds pelvic organs such as the bladder, rectum, uterus, vagina, and prostate

Compositional Layers

In many areas, the endopelvic fascia merges with adjacent tissue planes:

• Superiorly, it blends with the transversalis fascia
• Inferiorly, it connects with the perineal membrane and pelvic floor musculature
• Laterally, it is anchored to the pelvic sidewalls, forming fascial condensations

Location

The endopelvic fascia lines the entire lesser (true) pelvis, forming a supportive envelope around each organ. It occupies the space between the parietal pelvic fascia (on the walls) and the visceral pelvic fascia (on the organs), and extends into ligamentous structures such as the cardinal ligament, uterosacral ligament, and pubocervical fascia. These condensations transmit neurovascular bundles and contribute to organ suspension and compartmentalization.

Boundaries

Fascial Condensations

In certain areas, the endopelvic fascia condenses into thickened ligament-like structures that serve to suspend or stabilize organs:

• Cardinal (Transverse Cervical) Ligament: Thickening between the cervix and pelvic wall; contains uterine artery and vein
• Uterosacral Ligament: Posterior extension to sacrum; stabilizes uterus and upper vagina
• Pubocervical Fascia: Supports bladder and anterior vaginal wall
• Rectovaginal Fascia: Forms a partition between the rectum and posterior vaginal wall
• Arcus Tendineus Fasciae Pelvis: A tendinous thickening of the fascia running from pubis to ischial spine; anchor for vaginal support

Function

• Pelvic Organ Suspension: Supports and maintains the position of bladder, uterus, rectum, and vagina/prostate
• Pressure Transmission: Distributes forces generated by intra-abdominal pressure to prevent organ descent
• Compartmentalization: Creates pelvic compartments that localize infections or hematomas (e.g., presacral, paravesical, pararectal spaces)
• Pathway for Vessels and Nerves: Transmits major neurovascular bundles to the uterus, bladder, rectum, and vagina/prostate
• Anchor for Surgical Procedures: Used as fixation points during pelvic reconstructive surgeries

Innervation and Vascularization

Though not innervated in the classical sense, the endopelvic fascia contains abundant autonomic nerve fibers (sympathetic and parasympathetic) within its fascial condensations, especially near the uterosacral and cardinal ligaments. These nerves are part of the inferior hypogastric plexus and pelvic splanchnic pathways. Blood supply arises from branches of the internal iliac artery:

• Uterine artery (in females)
• Vaginal artery (in females)
• Inferior vesical artery (in males and females)
• Middle rectal artery

Histology

Histologically, the endopelvic fascia is dense irregular connective tissue rich in type I collagen, with some elastic fibers and fibroblasts. It may contain adipose tissue in certain compartments (e.g., paravesical and pararectal spaces), and is relatively avascular compared to surrounding tissues. Fascial layers are continuous but exhibit regional specializations where they thicken, thin, or fuse with muscular aponeuroses.

Imaging and Surgical Anatomy

While not directly visible on physical examination, the endopelvic fascia can be evaluated using pelvic MRI and high-resolution ultrasound. It is of particular interest in urogynecologic and colorectal surgery, where fascial integrity plays a role in surgical outcomes.

• On MRI: Seen as low-intensity linear structures between organs (e.g., between bladder and vagina)
• In prolapse surgery: Structures like the arcus tendineus are used for vaginal vault suspension
• During radical hysterectomy: Dissection of the cardinal ligament and careful nerve-sparing within the fascia are critical

Clinical Significance

• Pelvic Organ Prolapse: Weakening or tearing of the endopelvic fascia leads to descent of pelvic organs, including cystocele, rectocele, and uterine prolapse
• Childbirth Trauma: Vaginal delivery, especially with forceps or prolonged labor, can cause fascial rupture or avulsion
• Fascial Avulsion: MRI or ultrasound may reveal separation of fascial structures from their attachments, associated with vaginal wall bulging and functional incontinence
• Stress Urinary Incontinence: Disruption of pubocervical fascia impairs bladder neck support
• Fistula Formation: Infected or damaged fascial planes may predispose to vesicovaginal or rectovaginal fistulae
• Endometriosis: May involve the uterosacral ligaments, part of the endopelvic fascia, contributing to chronic pelvic pain