Pediatric Urology Surgical Anatomy of Urogenital Diaphragm and Course of Its Vessels in Exstrophy-Epispadias Shiv Narain Kureel, Archika Gupta, and R. K. Gupta 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 Ͼ5 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. UROLOGY 78: 159–163, 2011. © 2011 Elsevier Inc. he surgical anatomy of the exstrophy bladder has tral bulbospongiosus muscle), and, proximal to the bul- been described by Brock and O’Neil as follows: bospongiosus muscle, the external urethral sphincter T“Classic bladder exstrophy may be conceptualized should be present. However, studies using 3-dimensional by the visual image of what would occur if one blade of computed tomography (CT) and 3-dimensional magnetic a pair of scissors were passed through the urethra into the resonance imaging (MRI) have reported other anatomic bladder of a normal person, the other blade were used to details of the exstrophy bladder.3-7 In contrast, the sur- cut through the layers of the skin, abdominal wall, ante- gical anatomy of the urogenital diaphragm and its vessels rior wall of the bladder and urethra, the symphysis pubis has never been described. and the cut ends were unfolded laterally as if the pages of The aim of the present study was to determine the a book were being opened.”1 Trendelenburg in 1906 anatomy of the muscles of the urogenital diaphragm and reported, “the physiological factors necessary both for its vessels in the exstrophy bladder, so the knowledge can urinary retention and [for] voluntary micturition are pres- be applied to improve the quality of repair of the exstro- ent.”2 If this is true, in the exstrophy bladder, all the phy bladder. muscle of the urogenital diaphragm (ie, the pair of is- chiocavernosus and transverse perinei muscles and cen- MATERIAL AND METHODS From the Department of Pediatric Surgery, CSM Medical University (previously King The present study was conducted only on male patients with an George Medical College), Lucknow, Uttar Pradesh, India; and Department of Radio- exstrophy bladder and included 9 patients with a classic exstro- diagnosis, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar phy bladder and 2 with incontinent epispadias. Only those Pradesh, India patients who presented at Ն5 years of age without previous Reprint requests: Shiv Narain Kureel, M.S., M.Ch., Department of Pediatric surgery and had volunteered to undergo MRI of the pelvis were Surgery, CSM Medical University, Lucknow, UP 226003 India. E-mail: [email protected] included in the study group. In addition to MRI, 5 patients, in Submitted: October 6, 2010; accepted (with revisions): November 19, 2010 whom the testes were not retractile and could be covered by an © 2011 Elsevier Inc. 0090-4295/11/$36.00 159 All Rights Reserved doi:10.1016/j.urology.2010.11.026 indigenously designed gonadal shield, also underwent CT of the or trapezoid, depending on the degree of diastases be- urogenital diaphragm with angiography. tween the pubic bones (Fig. 1A). MRI of the pelvis was performed using a 3.0 Tesla MRI The central perineal body was identifiable in all the scanner (GE Signa HDX scanner, General Electric, Milwaukee, patients with an exstrophy bladder as a midline node WI). The following sequences were done using an 8-channel with attachment of the fibers of the external anal sphinc- coil. First, pre- and postcontrast 3-dimensional liver acquisition ter on posterior side, the bulbospongiosus muscle on the with volume acquisition- extended view sequences were done using the following experimental parameters: repetition time, anterior side, and the transverse perinei muscles on each 4.5 ms; echo time, 2.1 ms; field of view, 440 mm; NEX, 0.72; side of the perineal body (Fig. 1A). The bulbospongiosus and matrix size, 320 ϫ 192. The scanning was done in the axial muscle was present on the perineal surface of the planes with a slice thickness of 1.0 mm, and postprocessing was urogenital membrane under the laid-open urethral done in the coronal and sagittal planes. A gadolinium dose of plate in all patients; however, its shape was short and 0.2 mmol/kg body weight was used for the angiography se- stubby (Fig. 1A). quence. Second, a T2-weighted 3-dimensional cube sequence The ischiocavernosus muscle was also present at the was done using the following experimental parameters: repeti- root of the corporal body in all the patients, with no tion time, 2400 ms; NEX, 1; field of view, 240 mm; and matrix apparent shortening or attenuation of the ischiocavern- ϫ size, 288 288, with a slice thickness of 1.0 mm. osus muscle in any of the patients and an orientation of After performing these sequences, surface and volume-ren- the fibers similar to the description of the normal anat- dered images were reconstructed using standardized protocols omy (Fig. 1A). on an ADW, version 4.4, Advantage Workstation (General Electric Health Care, Milwaukee, WI). The superficial transverse perinei muscle was very well CT of the pelvis was performed on a multidetector, 64-slice, developed in 7 patients but was absent in 3 patients; row helical CT scanner (Philips Brilliance 64, version 3.5, however, the orientation of the fibers and the shape and scanner; Philips Medical Systems, Highland Heights, OH) with site were similar to that of the normal anatomy (Fig. 1A). Essence technology, which provides a spatial resolution to the Posterior to the perineal body and around the anorec- images. This multidetector row helical CT scan was performed tum, the striated muscle complex of the external anal for area of interest limited to the urogenital diaphragm with a sphincter was seen and well developed in all the patients, 0.75 second/turn rotation time, 54 mm/s table speed, 64 ϫ with anterior displacement of the perineal body, external ϫ 0.625-mm collimation, 512 512 image matrix, 2-mm slice anal sphincter, and anorectum. thickness, 1-mm pitch, 3-mm reconstruction, and automated The triangular space between the ischiocavernosus, dose modulation to minimize the radiation exposure. Nonionic bulbospongiosus, and superficial transverse perineal mus- contrast medium iohexol-350 in dose of 2.5-5.0 ml/kg body weight at the rate of 2-5 mL/s and with a pressure of 250-300 psi cles was not only a potential space but had opened up as was used for the angiography sequence. an accentuated space through which the perineal mem- After obtaining the angiography sequence, 3-dimensional brane (inferior fascia of urogenital diaphragm) was clearly reconstruction of the images was done using various software visualized on the 3-dimensional image of the urogenital protocols (cardiac, orthopedic, volume-rendered, maximum in- diaphragm (Fig. 1A). It was found that this space con- tensity projection) preloaded with on Extended Brilliance tained the perineal artery and its branches on the MRI 190-P workstation (Philips Medical Systems, Highland Heights, angiogram and CT angiogram (Figs. 1B and 2A). OH) to directly analyze the muscle orientation in the urogen- ital diaphragm and the course of the pudendal vessel. Further- more, to explore the course of the perineal artery, deep penile Vessel Course in Urogenital Diaphragm artery, and dorsal penile artery, limited digital dissection of the The CT angiogram and MRI angiogram revealed the volume-rendered images was performed on this workstation, course of the internal pudendal artery in the Alcock’s and the images were stored. canal well above the ischial tuberosity (Fig. 1D), giving its muscular branches to the external anal sphincter. RESULTS Just at the border of the ischium, deep to the attach- ment of the corpora, 3 terminal divisions of the internal Urogenital Diaphragm and Its Muscles pudendal artery were very well visualized. First, a dorsal The perineal view of the 3-dimensional reconstruction of artery to the penis was seen ascending up along the inner the urogenital diaphragm in the patients with an ex- edge of the ischiopubic ramus and left the ischiopubic strophic bladder revealed a well-defined perineal mem- ramus in the middle to lie on the lateral aspect of cor- brane stretched between the right and left ischiopubic poral body on each side (Fig.