Characterizing the Topography of the Vesical Portion of the Inferior Hypogastric Plexus and its Associated Endopelvic Fascial Planes: Informing Nerve‐sparing Ureteric Reimplantation Surgery

Abstract

Extravesical ureteric reimplantation is an effective treatment for vesicoureteral reflux. Concerningly, when performed bilaterally, it is associated with a 10-15% incidence of postoperative urinary retention and is postulated to be caused by iatrogenic damage to the nearby pelvic autonomic nerves. Unfortunately, an effective nerve-sparing surgical approach is limited by a lack of comprehensive anatomical knowledge of these nerves (i.e., location, distribution, density). Thus, this study aims to investigate the anatomy of the autonomic nerves within the endopelvic fascial planes and in the vicinity of the ureterovesical junction (UVJ), in fresh and ethanol-phenol-fixed human cadavers. To address this, the present study utilized gross dissection to identify the course of the autonomic nerves within the endopelvic fascial planes to contextualize their anatomical position and aid in surgical identification (Objective 1). Subsequently, we sought to examine the position and density of pelvic autonomic nerve fibers in the soft tissue surrounding the UVJ using western blot and semi-quantitative densitometry analysis (Objective 2). Findings from nine specimens (n= 9 cadavers; 8 males, 1 female) revealed a common endopelvic fascial plane including the gonadal vessels, ureters, and hypogastric nerves (from lateral to medial, respectively), that overlays the abdominal aorta. The region posterior to this plane was found to be continuous with the pre-sacral space inferiorly. The fascial plane containing the vas deferens in male specimens was differentiable from this common plane and can be seen intersecting proximal to the UVJ. The characterization of pelvic autonomic nerve fiber density, specifically surrounding the UVJ using western blot analysis, is ongoing. This study provides the first identification of hypogastric nerves (medial), ureters (between) and gonadal vessels (lateral) situated in a common endopelvic fascial plane (n= 9), an inferior continuation of the renal fascia, specifically the internal layers of Gerota's & Zuckerkandle's. Knowledge of these endopelvic fascial planes, paired with ongoing densitometry analysis in Objective 2, will provide the necessary anatomical foundation for future research to further refine nerve-sparing surgical approaches of ureteric reimplantation. Acknowledgements: Kaitlin Marshall, Dale Fournier, Mariyan Jeyarajah, Stephen Renaud, Haley Linklater, Kevin Walker and the UWO anatomy lab donors.