The 'urogenital diaphragm', external urethral sphincter and radical prostatectomy.

BACKGROUND

The present study was performed to determine whether a 'urogenital diaphram' exists, to examine the true nature of the striated external urethral sphincter and to evaluate whether the standard technique for radical prostatectomy damages the external sphincter.

METHODS

Fifty radical prostatectomies were performed using optical magnification and the dorsal bunching technique, and the external sphincter was carefully examined. Ten human cadavers and one 5-year-old baboon were dissected with longitudinal (sagittal) and transverse sections being taken through the prostate apex, membranous and bulbar urethrae. During the standard technique for dorsal vein control during radical prostatectomy, the tissue incorporated within the ligature was examined for striated muscle.

RESULTS

No 'urogenital diaphragm' could be demonstrated in any human or baboon tissue. The striated external urethral sphincter is a cylinder of muscle surrounding the membranous urethra, extending from the perineal membrane to the prostate and continuing over the prostate as part of the anterior fibromuscular stroma. Striated muscle was present in the ligated material from the dorsal venous complex.

CONCLUSIONS

The 'urogenital diaphragm' is a myth. The standard technique of radical prostatectomy significantly damages the external sphincter.