[Anatomical elucidation and histological study of pelvic autonomic nerve-plane based female fresh cadaver]

Objective: To investigate the rationality of nerve-plane sparing radical hysterectomy (NPSRH) for cervical cancer by observing the anatomical and histological characteristics of pelvic autonomic plane based on fresh cadaver. Methods: From October 2015 to September 2020, 14 fresh female cadavers were anatomically and histologically studied in the Laboratory of Anatomy and Embryology Department, Peking Union Medical College, Chinese Academy of Medical Sciences. The median age of the specimens was 79 years (range: 67 to 92 years). Twenty-eight hemi-pelvic specimens were obtained from 14 fresh female cadavers. NPSRH procedures were simulated in 8 hemi-pelvic cavities to prove its feasibility. Detailed dissection was conducted to recognize nerve plane and to observe the distribution of pelvic nerves in 10 hemipelvis. In the other 10 hemipelvis, whole parametrium tissue was taken from the crossing of ureter and the uterine artery to the ureterovesical entrance and be embedded, then continuous section was performed, and was stained by hematoxylin-eosin staining (HE) to observe the relationship of nerves and vessels. Immunohistochemical staining of S100, tyrosine dehydrogenase (TH), and vasoactive intestinal peptide (VIP) were performed to count and distinguish sympathetic and parasympathetic nerves, respectively. Results: (1) The pelvic autonomic nerve-plane was completely preserved in 7 of 8 hemipelvis by simulating NPSRH. (2) After detailed dissection in 10 hemipelvis, it was found that hypogastric nerve, pelvic splanchnic nerve, and their confluence of inferior hypogastric plexus were distributed in a planar statelocating in the ureteral mesentery and its caudal extension. This nerve plane showed a cross relationship with deep uterine vein and its branches. The bladder branches and vesical venous plexus were closely related to the inferior hypogastric plexus. The middle vesical vein and inferior vesical vein were intact in 7 of 10 hemipelvis, and either vesical vein was missing in 3 of them. It was observed that the vesical venous plexus communicated with the deep uterine vein trunk on the medial side of the nerve plane in 6 hemipelvis, while flowed into the deep uterine vein on the lateral side of the nerve plane in 2 hemipelvis, and in the other 2 hemipelvis it directly flowed into the internal iliac vein. (3) It was revealed that autonomic nerves were continuously distributed beneath the ureteral with sagittal plane by HE staining. The average nerve content below the ureteral width was 70.9% of the total in nerve plane by S100 staining. TH and VIP staining showed that the average number of sympathetic fibers was 13.5 and parasympathetic fibers was 8.2, reminding sympathetic predominated. Conclusion: Pelvic autonomic nerves are mainly distributed within the mesangial plane below the ureter, which provides an anatomic justification for NPSRH.