Nerve-sparing gynecologic surgery was originally developed as a technique to mitigate the effects of radical hysterectomy on urinary, defecatory and sexual function(1). Nerve-sparing techniques have also been adapted to benign gynecologic surgery, allowing for complete excision of deeply infiltrating endometriosis while preserving autonomic pelvic function(2). While landmark-based approaches have been used successfully to preserve nerves by recognizing key structures that marks boundaries of autonomic nerves, laparoscopy has allowed for improved visualization of nerve fibers and experts thus increasingly advocate for nerve sparing through direct visualization of nerves. Implementation of nerve-sparing techniques, irrespective of approach, has been limited, however. A barrier to the widespread implementation of nerve-sparing surgery is the inconsistency in terminology, to the point where several different names can be used to describe the same structure within a single article(3). Such inconsistency makes studying, understanding and learning nerve sparing approaches more challenging. The objective of this systematic review is to synthesize the terminology utilized in nerve-sparing surgical literature and propose standardized and non-conflicting terms to allow for consistent vocabulary.

We performed a literature search on PubMed using the search terms “Pelvis” and “nerve-sparing”. Articles focused on exclusively non-gynaecologic surgery (ie. prostate cancer, colorectal cancer) were excluded, as were articles based on animal studies. A narrative review was performed in order to synthesize terminology, focusing on nerves, fasciae, ligaments, and retroperitoneal spaces. Relevant references not appearing in the original search but identified during the reading of full articles were also included in this analysis. Selected papers were read in full and consensus was reached within the group of reviewers on which term was more appropriate to be standardized, based on popularity (frequency at which they were found in the literature) and possibility of overlapping terminology with other structures names. All of the terms were discussed by all authors.

Initially, 216 articles were identified. After abstract screening, 71 articles were included in the full text review. 56% of articles (40/71) focused on cervical cancer, 18% (13/71) on deeply infiltrating endometriosis, and the remainder on a combination of the two; other gynecologic malignancies; pelvic organ prolapse; and non-specific. In terms of article type, cadaveric or anatomical studies were most common (34%, 24/71); followed by surgical videos (21%, 15/71) and case series or case reports (17%, 12/71). Several cohort or cross-sectional designs (11), literature reviews (9), and 1 randomized control trial were also included. Findings were synthesized both narratively and visually (Figures 1 and 2). 

Pelvic autonomic nerves carry both sympathetic and parasympathetic innervation, as well as visceral afferent sensory fibers, to the uterus, vagina, bladder and rectum. Sympathetic innervation stems from the superior hypogastric plexus (SHP), which is formed by branches of the sympathetic chain ganglia from T10-L3 and the periaortic sympathetic trunk. The SHP then divides into the left and right hypogastric nerves, also referred to as right and left SHP branches. The hypogastric nerve on each side of the pelvis is joined by pelvic splanchnic nerves, which are parasympathetic fibers from the ventral rami of S2-S4 spinal levels. Together these form one inferior hypogastric plexus (IHP) at each side. The IHP is variably referred to as the pelvic plexus, the pelvic nerve plexus or neural pelvic plexus. The IHP then gives rise to the vesical, uterovaginal and rectal branches. These have also been termed the vesical, vaginorectal and inferior rectal plexi, respectively. 

The endopelvic fascia consists of a parietal layer overlying the levator ani and a visceral layer that wraps the pelvic organs and attaches them to the pelvic walls. The endopelvic fascia is also called pelvic fascia, uterohypogastric fascia, and hypogastric fascia. The thickenings of the visceral endopelvic fascia are often referred to as ligaments, including the uterosacral, cardinal, and vesicouterine ligaments. The parametrium can be divided into an anterior, lateral, and posterior part. The anterior or ventral parametrium contains the anterior leaf of the vesicouterine ligament (VUL), also referred to as the superficial/anterior layer/part of the VUL or the cranial VUL. Some authors also refer to this structure as the vesicocervical ligament with similar directions qualifiers. The lateral parametrium is comprised of the cardinal ligament and the lateral ligament. The posterior parametrium is a convergence of the uterosacral ligaments (aka sacrouterine, rectouterine, or uterosacral peritoneal fold), the rectovaginal ligaments, and the lateral rectal ligaments (rectal stalks, rectal pillars, rectal wings). The paracolpium also has a ventral component commonly regarded at the posterior leaf of the VUL but may also be termed the deep/posterior layer/part of the VUL or the caudal VUL. The posterior VUL may also be called the vesicocervical or vesiovaginal ligament with directional qualifiers. 

The pelvic avascular spaces were discussed in 51% of included papers, with the pararectal spaces being most commonly described. While variance was noted with respect to the level of detail described, generally speaking there was consensus regarding the borders of these spaces; namely, the cardinal ligament ventrally, the presacral fascia and sacrum dorsally, the internal iliac artery laterally, the rectum medially, the peritoneum of the posterior leaf of the broad ligament cranially, and the levator ani muscle caudally. Some studies further described the medial pararectal – or Okabayashi’s – space, and the lateral pararectal – or Latzko’s – space. While the ureter or mesoureter is broadly used as the defining structure dividing medial from lateral, variance was noted amongst other described landmarks and we do not think this division of the pararectal space is useful. These inconsistancies were echoed in other noted pelvic spaces, such as the pre-sacral, retrorectal, paravaginal, pre-rectal, paravesical, and retropubic spaces.

We propose consistent terminology of the pelvic autonomic nerves to include the following: periaortic sympathetic trunk, SHP, hypogastric nerves, pelvic splanchnic nerves, IHP, and vesical, uterine, and rectal branches. The endopelvic fascia is described with various nomenclature, with ligamentous structures appearing to reflect the ways in which dissections are carried out. Finally, spaces have been quite consistent in the literature. These structures and their proposed name standardization are summarized in the figures below.

Surgeons and anatomists should use consistent terminology to facilitate an increased uptake of nerve-sparing techniques in gynecologic surgery.

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