Surgical anatomy of urogenital diaphragm and course of its vessels in exstrophy-epispadias.

OBJECTIVES To report the surgical anatomy of the muscles of the urogenital diaphragm and the pattern of its vessels in the classic exstrophy bladder and incontinent epispadias. METHODS A total of 11 patients, 9 with unoperated classic exstrophy and 2 with incontinent epispadias, who were >5 years old at presentation, were selected for the present study. Magnetic resonance imaging of the pelvis was performed using a 3.0 T magnetic resonance imaging scanner and an 8-channel coil. Computed tomography was performed for 5 patients using a multidetector row helical computed tomography scanner. Angiograms of the vessels of the urogenital diaphragm were also obtained using magnetic resonance imaging and computed tomography. RESULTS A central perineal body was seen in all the patients, with attachment of the bulbospongiosus anteriorly, superficial transverse perinei laterally, and anal sphincter posteriorly. At the root of corpora, the ischiocavernosus muscle was also seen. The triangle among the ischiocavernosus, bulbospongiosus, and superficial transverse perinei muscle was accentuated and contained the perineal artery, indirectly indicating the course of the perineal nerve. The dorsal penile artery was nearer to the posterior edge of the ischiopubic ramus, before coursing on the lateral aspect of the anterior segment of the corpora. The deep transverse perinei muscle and laid open external urethral sphincter were also seen in the proximal planes of the urogenital diaphragm. CONCLUSIONS First, all the muscles of the urogenital diaphragm, including the external urethral sphincter, were present in the exstrophy bladder. Second, the perineal artery and its sphincteric branches were in the triangular space between the ischiocavernosus, bulbospongiosus, and superficial transverse perinei muscle. Finally, the dorsal penile artery ran along the inner edge of the ischiopubic ramus before lying on lateral aspect of the corpora.