3-dimensional neuroanatomy of the human fetal pelvis: anatomical support for partial urogenital mobilization in the treatment of urogenital sinus.

Purpose: Retrospective reviews suggest that the functional outcomes of surgery of the urogenital sinus have often been unsatisfactory and to our knowledge the long-term results of newer surgical techniques have yet to be evaluated. A precise understanding of pelvic fetal neuroanatomy is germane for optimizing surgical correction of the urogenital sinus.

Materials And Methods: The pelves of 10 human female fetuses were serially sectioned. Masson's trichrome staining and immunochemistry for the neuronal marker S100 (Dako Corp., Carpinteria, California) along with anatomical computer reconstruction allowed 3-dimensional analysis of the nerves in relation to the pelvic structures as an animated motion picture.

Results: Two types of neuronal structures were identified. 1) A dense perivisceral foil of branching nerves closely surrounded the pelvic organs. The localization of most nerves was on the external faces of the viscera with a limited fraction in the rectovaginal and urethrovaginal septa. This innervation was from the anterior cephalad periurethral area to the posterior caudal perirectal area. 2) A significant amount of nerves surrounded the cephalad urethra on its anterior and posterior faces.

Conclusions: Based on these anatomical data during surgical repair of a urogenital sinus we would advocate minimal mobilization of the lateral faces of the vagina, avoiding dissection of the proximal urethra above the pubic bone and electing a vaginal flap in severe cases.