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.