The female urethral sphincter: a morphological and topographical study

Area of Science:

• Female pelvic anatomy
• Urology
• Surgical anatomy

Background:

• The female urethral sphincter system's anatomy and innervation are crucial for maintaining continence, especially during pelvic surgeries.
• Understanding these structures is vital for procedures like anterior exenteration, which involves the removal of pelvic organs.

Purpose of the Study:

• To reassess the anatomy and topography of the female urethral sphincter system and its innervation.
• To evaluate the implications for urethra-sparing anterior exenteration and other surgical procedures.

Main Methods:

• Anatomical and histological studies on fetal and adult cadaveric specimens.
• 3D reconstruction of pelvic structures using computerized tomography and histological data.
• Simulated anterior exenteration on adult cadavers to assess urethral and sphincter mechanism implications.

Main Results:

• The proximal two-thirds of the female urethra's smooth muscle is organized into three distinct layers.
• Innervation from the pelvic plexus reaches the proximal urethra, potentially preservable during surgery.
• The striated rhabdosphincter, innervated by the pudendal nerve, is located in the caudal third of the urethra.

Conclusions:

• A distinct sphincteric structure at the bladder neck was not identified.
• The majority of rhabdosphincter fibers are located in the middle and caudal urethral thirds.
• Continence can be maintained after bladder neck and proximal urethra removal if innervation is preserved.