Neuroanatomy of the female continence complex: clinical implications.

Objectives: Improved understanding of pelvic neuroanatomy in women has led to modified surgical approaches and additional considerations in pelvic surgery. The innervation of the external urinary sphincter and urethra is not well defined in women, and, as such, the continence complex is not well understood.
Methods: Fourteen pelvic sections from seven fresh female cadavers were dissected to investigate the neuroanatomy of the female continence complex.
Results: Neuroanatomic dissections of the continence mechanism revealed that branches of the pelvic nerve travel beneath the fascia of the levator ani muscle and approach the urinary sphincter in near midline position, posterolateral to the rectum. This pelvic nerve branch passes laterally around the vagina and rectum to enter the sphincter musculature at the 5-o'clock and 7-o'clock positions. The pudendal nerve, traveling in the pudendal canal, gives an intrapelvic branch that courses to the urinary sphincter. At the level of the proximal urinary sphincter, it joins the pelvic nerve branch to the urinary sphincter.
Conclusions: These neuroanatomic dissections provide a basis for surgical modifications that may address a variety of concerns regarding urinary continence in female surgical patients. With improved understanding of the female continence complex, we may now have a more precise anatomic explanation for the high failure rates associated with transvaginal urethral suspension procedures. Additionally, awareness and preservation of the continence nerves during cystectomy may allow for greater use of orthotopic bladder replacement in women.