Applied anatomy of female pelvic plexus for nerve-sparing radical hysterectomy(NSRH)

The surgical concept of preserving the pelvic autonomic nerves during radical cervical cancer surgery was first proposed by Japanese scholar Okabayashi in 1921 [13]. The procedure of NSRH was improved by anatomists and surgeons over the years [14‐16]. Surgeons should be aware of the composition and course of the pelvic autonomic nerves as well as the relationship between nerves and major anatomical landmarks to achieve the radicality and safety of radical hysterectomy [17].

Great morphological differences of SHP existed between individuals. Fenestrated and cord-like shape morphology of SHP were observed, just like what Ripperda found in their study [18]. While Kutlu observed three patterns of SHP, including mesh, single and fiber, among which the mesh type is over 50% [19]. Correia et al. proposed an original morphological classification with six types, based upon the anatomical arrangement of the nervous fibers [20]. According to our observations the fibers of the SHP were located left to the midline in three-fifths of the specimens, the ratio of SHP located to the left and right of the midline was 3:1. Thus, it is suggested to carrying out an incision of the posterior peritoneal plane being along the right side of the midline and abdominal aorta in order to avoid undesirable consequences. These findings were supported by other investigators [16, 21]. It is also a matter of debate that whether SHP can be also identified as presacral nerve. The SHP comprised fibers both from the lumbar sympathetic and from thoracic sympathetic through the celiac plexus, besides, the SHP contained the terminal branches of the major and minor splanchnic nerves [22]. Thus, it’s not accurate to characterize the SHP as a single presacral nerve. As a direct continuation of SHP, the HN follows a predictable course and can be identified, dissected, and isolated during pelvic surgery, making it an important landmark to trace the visceral branches of the IHP down the HN and preserve the pelvic autonomic innervation [23].

The IHP was a mixture of nerve fibers that running in front of the sacrum and on either side of the rectum, most of it were located below the uterine vessels and was an irregular flat neural network [24, 25]. We believed that it’s not necessary to describe the exact shape of IHP, such as triangular anterior sheet or quadrilateral posterior sheet. Because its shape may change due to anatomical manipulation and artificial traction, as well as changes in the location of organs and connective tissue. The point is paying attention to the adjacent and relative positions of its branches and blood vessels and fascia [26]. Studies have shown that the uterine blood vessels and vesical veins can be used as landmarks to locate the pelvic plexus. The uterine veins can be identified in the broad ligament within the mesometrium, usually accompanied by the ascending branch of the uterine artery. The superficial uterine veins were not visible in every specimen, but the DUV always came from the uterine plexus and passed below the ureter [27]. Thus, it’s easy to identify the PSN below the DUV [28]. We suggested that the processing of the blood vessels within the cardinal ligament should be approached cautiously, in order to avoid damaging and fully expose the PSNs. The middle rectal artery (MRA) is also a key anatomical structure for surgical procedures of NSRH, although the location of the MRA was not as fixed as the location of the DUV [29], and it’s more difficult to not to damage the nerves during separating and dissecting this vessel because the MRA extends beneath and across the IHP [30], some scholars have suggested that the middle rectal artery can help to protect the IHP. Possover et al. identified the MRA as a landmark to separate the vascular from the neural part in radical hysterectomy Rutledge type III [31], the study by Centini et al. pointed out that the MRA is a landmark to identify the IHP after dissection of the right medial pararectal fossa in the surgery for endometriosis [32].

It is also important, in terms of surgical nerve preservation, to know not only the location of the pelvic plexus itself, but also the placement of the branches from the pelvic plexus to the various organs, especially the bladder [33]. The vesical veins originated from the cervix, ran beneath the uterine artery and ureter, and eventually joined the DUV [34]. Careful dissection and preservation of bladder branches is the most difficult and critical step in NSRH. During NSRH surgery, injuries of bladder branches often happened when dissecting the vesico-vaginal ligament [35]. After meticulous separation of the connective tissues in the anterior leaf of the vesico-vaginal ligament, the middle and inferior vesical veins can be appreciated in the cranial portion of the posterior leaf of the vesico-vaginal ligament [36]. The bladder branches of can be visualized after the section of middle and inferior vesical veins [37].