Neuro-anatomy of the posterior parametrium and surgical considerations for a nerve-sparing approach in radical pelvic surgery

Efforts to improve approaches to the so called "parametrium" with minimally invasive and less dangerous techniques have led to a better study of the anatomic location and composition of that region. Nevertheless, many misconceptions and confusions about the anatomy of the posterior parametrium and its structures still remain. This study aimed to review anatomic and surgical data and to identify several clear landmarks and surgical steps for a nerve-sparing approach to posterior parametrectomy in the course of radical pelvic surgery with or without rectal resection. The literature and anatomic dissections of fresh, embalmed, and formalin-fixed female pelvis cadavers were reviewed. The authors' laparotomic and laparoscopic case series also was reviewed for deep-infiltrating endometriosis as well as uterine, ovarian, and rectal cancer. The anatomic entity commonly termed the "posterior parametrium" can be identified as the conjunction of three important anatomic structures (ligaments): the cranial structure (uterosacral ligaments), the caudad structure (rectovaginal ligaments), and the laterocaudad structure (lateral rectal ligaments). Identification of these structures (containing autonomic innervations for pelvic viscera) may allow an accurate nerve-sparing surgical approach in many radical pelvic operations. The incidences of urinary, rectal, and sexual morbidity after radical pelvic surgical procedures for oncologic diseases (rectal/ovarian cancer, advanced endometrial/cervical cancer, posterior pelvic recurrences) and deep severe endometriosis can be reduced by better knowing and dissecting the right embryo-anatomic planes of the so-called "posterior parametrium.".