Anatomical approach for surgery of the male posterior urethra

OBJECTIVE: To investigate, in a morphological study, the anatomy of the male rhabdosphincter and the relation between the membranous urethra, the rhabdosphincter and the neurovascular bundles (NVBs) to provide the anatomical basis for surgical approach of the posterior urethra as successful outcomes in urethral reconstructive surgery still remain a challenging issue. MATERIALS AND METHODS: In all, 11 complete pelves and four tissue blocks of prostate, rectum, membranous urethra and the rhabdosphincter were studied. Besides anatomical preparations, the posterior urethra and their relationship were studied by means of serial histological sections. RESULTS: In the histological cross-sections, the rhabdosphincter forms an omega-shaped loop around the anterior and lateral aspects of the membranous urethra. Ventrally and laterally, it is separated from the membranous urethra by a delicate sheath of connective tissue. Through a midline approach displacing the nerves and vessels laterally, injuries to the NVBs can be avoided. With meticulous dissection of the delicate ventral connective tissue sheath between the ventral wall of the membranous urethra and the rhabdosphincter, the two structures can be separated without damage to either of them. This anatomical approach can be used for dissection of the anterior urethral wall in urethral surgery. CONCLUSIONS: Based on precise anatomical knowledge, the ventral wall of the posterior urethra can be dissected and exposed without injuring the rhabdosphincter and the NVBs. This approach provides the basis for sparing of the rhabdosphincter and for successful outcomes in urethral surgery for the treatment of bulbo-membranous urethral strictures.