Urogenital Diaphragm Research Articles

Endoscopic Realignment of Prostatomembranous Urethral Disruptions

Prior to discussing the endoscopic approach to realignment of prostatomembranous urethral disruptions, some discussion of the general approach to management of prostatomembranous urethral disruptions is appropriate. There have been advocates of both immediate and delayed repair of prostatomembranous urethral disruptions. Proponents of delayed repair of these injuries have suggested that immediate repair results in further damage to the delicate neurovascular structures in the urogenital diaphragm which have been injured. They have suggested that it is better to allow these acute injuries to subside prior to urethral reconstruction. However, advocates of immediate repair of these injuries have argued that impotence and incontinence in these patients are the result of the injury itself and not the method of management. Furthermore, they believe that urethral realignment over a urethral catheter is no more traumatic or less anatomic than a delayed urethroplasty through the fibrotic urogenital bed that results from the injury. The controversy between early versus delayed repair of prostatomembranous urethral disruptions originated in 1972 when Morehouse reported that early repair of these injuries resulted in excess incontinence and impotence compared with initial suprapubic tube placement alone followed by a delayed ~rethrop1asty.l~ In a follow-up study published in 1980, they reported on 58 consecutive patients treated with complete prostatomembranous urethral disruptions managed by initial suprapubic tube placement alone and delayed urethral reconstr~ction.'~ They reported remarkably good results, including a 0% incidence of stricture, a 2% incidence of mild stress incontinence, and only 10% impotence. They compared these results with those of another group of patients who were referred to their medical center after unsuccessful attempts at immediate repair. Not unexpectedly, the patients who underwent unsuccessful attempts at immediate repair had worse results. This report has been appropriately criticized because, in essence, they are comparing those patients who underwent successful management with initial suprapubic tube placement followed by delayed urethroplasty with those patients who were failures of immediate realignment.

MANAGEMENT OF AN INFECTED HEMATOMETROCOLPOS IN A PATIENT WITH CONGENITAL ADRENAL HYPERPLASIA AND VAGINAL STENOSIS

A 12-year-old girl presented with abdominal pain associated with menses. She had a history of congenital adrenal hyperplasia, and had undergone clitoral recession and posterior flap vaginoplasty at age 18 months. Evaluation revealed abdominal tenderness and pyuria. She was treated for urinary tract infection. The pain worsened and was associated with fever, and the patient was seen by a urologist. Ultrasound demonstrated a pelvic mass consistent with a dilated, fluid filled vagina. The patient underwent endoscopy through the common urogenital sinus but the vaginal introitus could not be identified. Symptoms improved significantly on intravenous antibiotics, and she was referred for further evaluation. Physical examination demonstrated suprapubic tenderness, an enlarged clitoris and a single perineal opening. Rectal examination revealed a large bulging mass anteriorly. Urinalysis showed no infection. The perineal opening was cannulated and a voiding cystourethrogram showed mass effect with anterior displacement of the bladder. Despite several bladder fillings and voidings, no contrast material entered the vagina. MRI was performed to characterize the suspected hematometrocolpos. The sagittal fast spin echo series showed a large midline pear-shaped, fluid filled mass displacing and compressing the bladder and rectum (see figure). Superiorly the mass was contiguous with a small fluid filled uterus and inferiorly it appeared obstructed just above the urogenital diaphragm. The signal intensity of the vaginal and uterine contents was suggestive of proteinaceous fluid and did not follow the signal characteristics of simple blood products. Based on MRI and history, infected hematometrocolpos due to vaginal stenosis was suspected. At cystoscopy the bladder neck was 2 cm. from the perineal opening of the urogenital sinus. It was elevated due to compression from the posterior mass. The bladder contained abundant whitish debris but was otherwise unremarkable. The vaginal introitus was not visible along the urogenital sinus. Based on the MRI and using real-time transabdominal ultrasound guidance, the stifF end of a 0.038-inch polytetrafluorwthylene coated guide wire was passed through the wall of the urogenital sinus and into the vagina. The tract

ANATOMY OF RADICAL PROSTATECTOMY AS DEFINED BY MAGNETIC RESONANCE IMAGING

Purpose We examined and defined anatomical structures relevant to radical prostatectomy using magnetic resonance imaging. Materials and Methods Before radical prostatectomy, 15 men underwent high-resolution magnetic resonance imaging studies of their pelvic floors (fast spin echo, T2 weighting of 3- to 4-mm. contiguous or overlapping slices) in axial, coronal, and sagittal planes. Results Pubovesical ligaments, rather than the commonly reported puboprostatic ligaments, we observed attaching the bladder-prostate unit to the pubis. We suggest that the part of the urethra that extends from the apex of the prostate to the bulb of the penis, which is surrounded by the striated sphincter, should be termed the sphincteric urethra rather than the membranous urethra. Further, we found no evidence that supports the traditional concept of a urogenital diaphragm. The lower part of the striated urethral sphincter was flanked on its sides by the anterior recesses of the ischioanal fossae. The portion of the levator ani, which we have termed the puboanalis sling, flanked the apex of the prostate. The most anteromedial portion of this sling inserts into the perineal body and should be termed the puboperinealis. The terminal part of the gastrointestinal tract (the part continued beyond the levator ani) should be termed the anal canal, not the rectum, as used frequently in the urologic literature. Therefore, the initial plane of dissection in radical perineal prostatectomy passes along the anterior portion of the anal canal, not the rectum. Conclusion We used magnetic resonance imaging to study male pelvic floor and perineal anatomy without the artifact of dissection. This study allowed us to devise a more precise nomenclature with respect to radical prostatectomy and, in so doing, to provide a better understanding of both the retropubic and the perineal operations.

Female pelvic floor: endovaginal MR imaging of normal anatomy.

To demonstrate the anatomy of the female pelvic floor with endovaginal magnetic resonance (MR) imaging. Ten healthy nulliparous volunteers (age, 22-26 years) underwent MR imaging with an endovaginal coil. Findings on endovaginal MR images in the volunteers were correlated with findings on endovaginal MR images and cross-sectional anatomic slices obtained in three cadavers. The endovaginal coil was well tolerated by all volunteers. Pelvic floor structures such as the pelvic diaphragm and the urogenital diaphragm were well depicted. Previously undescribed urethral supporting structures--the periurethral and paraurethral ligaments--were visualized. The zonal anatomy of the urethra was clearly visible. The endovaginal MR imaging findings in the volunteers correlated with the endovaginal MR findings and gross anatomy in the cadavers. Endovaginal MR imaging clearly demonstrates the anatomy of the female pelvic floor and urethra.

Distinguishing Cowper's glands from neoplastic and pseudoneoplastic lesions of prostate: immunohistochemical and ultrastructural studies.

Mucin-producing Cowper's glands, which are situated in the urogenital diaphragm, can be sampled inadvertently by transurethral resection of the prostate and rarely by needle biopsy. Because they are small, closely packed glandular units, Cowper's glands can be misinterpreted as prostatic adenocarcinoma. A panel of immunoperoxidase and mucin stains performed on 10 Cowper's glands showed negative immunoreactivity for prostatic-specific antigen, prostatic alkaline phosphatase, S-100 protein, and carcinoembryonic antigen. Acini in nine of the 10 Cowper's glands were negative for high-molecular-weight cytokeratin K-903 (34beta E12). One case showed faint focal staining of cells around the periphery of acinar units. Smooth muscle actin consistently stained the periphery of acini in all cases. Ultrastructural examination of one Cowper's gland showed the presence of myoepithelial cells at the periphery of the acini. Contrary to previous reports, the acini were lined by a prominent secretory cell layer underlain by an attenuated myoepithelial cell layer. A negative stain for K-903. without additional immunohistochemical study on Cowper's glands taken during transurethral resection or needle biopsy, may substantiate an erroneous diagnosis of prostatic adenocarcinoma. This potential misdiagnosis of carcinoma can be averted if samples stain positive for mucin and smooth muscle actin and negative for prostate-specific antigen and prostatic alkaline phosphatase.

Localization of the prostatic apex for radiotherapy treatment planning using urethroscopy

To assess the ability of computed tomography (CT) scans and retrograde urethrograms to accurately define the prostatic apex in the craniocaudad dimension, using urethroscopy as a reference. Plain film radiographs of the pelvis were obtained in 15 patients with early-stage adenocarcinoma of the prostate, with the tip of a urethroscope held in place at the external sphincter, which most closely approximates the prostatic apex. The scope was then withdrawn, and a retrograde urethrogram was performed. Immediately afterwards, a CT scan of the pelvis was obtained. Because differential filling of the bladder and rectum affects the position of the prostatic apex, patients voided prior to rather than in between the three consecutive studies. The urethroscopy-defined prostatic apex was located 4 +/- 8 mm (mean +/- SD) superior to the CT-defined apex, 13 +/- 3 mm (mean +/- SD) superior to the urethrogram tip and 30 +/- 7 mm (mean +/- SD) superior to the ischial tuberosities. There was significant interobserver variability in the location of the prostatic apex as determined by CT scans. Placement of the inferior border of the radiation portals at the ischial tuberosities would have resulted in irradiation of > or = 20 mm bulbar urethra, as defined by the dye column of the retrograde urethrogram, in 6 out of 15 (40%) of the patients and irradiation of < 10 mm bulbar urethra in 2 out of 15 (13%) of the patients. Because the prostate blends inferiorly with the urogenital diaphragm, CT scans do not allow one to precisely localize the prostatic apex. Due to anatomic variability, the ischial tuberosities do not allow one to accurately localize the prostatic apex. Retrograde urethrograms provide helpful supplemental information regarding the position of the prostatic apex for radiotherapy treatment planning.

Impact of differences in ultrasound and computed tomography volumes on treatment planning of permanent prostate implants

Both ultrasound (US) and computerized tomography (CT) images have been used in the planning of prostate interstitial therapy. Ultrasound images more clearly define the apex and capsule of the prostate, while CT images define seed positions for postimplant dosimetry. Proper registration of the US volume with the CT volume is critical to the assessment of dosimetry. We therefore compared US and CT prostate volumes to determine if differences were significant. Ten consecutive patients entered in an interstitial implant program were studied by pretreatment US. In addition, pretreatment CT scans were obtained and three physicians independently outlined the dimensions of the prostate on these images. The patients subsequently underwent placement of radioactive 125I or 103Pd. Postimplant CT images were obtained the next day and the postimplant prostate volumes were outlined by the same three physicians. Seven of 10 patients underwent late CT scans 9-14 months postimplant for comparison of preimplant and immediate postimplant CT studies. There were differences between US and CT volumes. Although the physician-to-physician variation was significant, the trends were consistent, with US prostate volume typically smaller (47%) than the preimplant CT volume and markedly smaller (120%) than the postimplant CT volume. Prostate volumes derived from late CT images did not consistently return to preimplant levels. Significant differences in volume of the prostate structure were found between US and CT images. The data suggests that: (a) Implants planned on CT tend to overestimate the size of the prostate and may lead to unnecessary implantation of the urogenital diaphragm and penile urethra. (b) Registration of initial US and postimplant CT prostate volumes required for accurate dosimetry is difficult due to the increased volume of prostate secondary to trauma. (c) Further study to determine the optimal time for the postimplant CT is necessary.

THE ‘UROGENITAL DIAPHRAGM’, EXTERNAL URETHRAL SPHINCTER AND RADICAL PROSTATECTOMY

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

Blunt Urethral Trauma: A Unified, Anatomical Mechanical Classification

We propose a simple, anatomically based classification of blunt urethral injury as a replacement for currently used classifications, which are not comprehensive, anatomically inconsistent or based on a mixed anatomical/mechanistic formula. The latter are difficult to learn and use, and have not been universally adopted. We reviewed most of the currently used general uroradiological, emergency radiological and urological textbooks to define the classification of urethral injuries that is most widely accepted. Most authors use the Colapinto and McCallum classification, modifications thereof or the older surgical classification of urethral injuries, which simply divides such injuries anatomically into anterior and posterior. However, there is little consensus about the best classification and none includes all of the blunt injuries of the urethra. To correct these difficulties we devised a comprehensive and anatomically consistent classification. The proposed classification categorizes blunt urethral trauma as I-posterior urethra intact but stretched (Colapinto and McCallum type I), II-partial or complete pure posterior injury with tear of membranous urethra above the urogenital diaphragm (Colapinto and McCallum type II), III-partial or complete combined anterior/posterior urethral injury with disruption of the urogenital diaphragm (Colapinto and McCallum type III), IV-bladder neck injury with extension into the urethra, IVA-injury of the base of the bladder with periurethral extravasation simulating a true type IV urethral injury and V-partial or complete pure anterior urethral injury. The proposed classification is anatomically valid and includes all of the common types of blunt urethral injuries. Universal adoption of this system should permit comparison of various management/treatment modalities at various institutions.

Anatomy and innervation of the rhabdosphincter of the male urethra

The striated sphincter of the male urethra and its innervation are still a subject of controversy. Essentially, two concepts of its anatomy can be found in the literature. Some authors describe the rhabdosphincter as part of the urogenital diaphragm caudal to the prostate, others as a striated muscle which extends from the base of the bladder to the "urogenital diaphragm." In a combined anatomic-histologic study the striated sphincter and the pudendal nerve were examined by means of anatomical dissections and serial anatomical as well as histological sections of 12 male pelves. Furthermore, radical prostatectomy was performed in a cadaver specimen; subsequently, the so-called "urogenital diaphragm" was excised and then examined histologically. The varying number of striated muscle fibers caudal to the prostate is of particular interest. In fetuses, there are abundant striated muscle fibers dorsal to the membranous urethra, where they are arranged as a circular collar around the urethra. In the adult male, hardly any striated muscle fibers can be found dorsal to the urethra; in a majority of cases this region is devoid of striated muscle fibers. Inserting dorsally in the perineal body, the fibers form an omega-shaped loop around the anterior and lateral aspects of the membranous urethra. The existence of a "urogenital diaphragm" and a strong, circular, striated "external sphincter urethrae" completely encircling the urethra caudal to the apex of the prostate could not be confirmed by our anatomical and histological investigations. Our study shows that the striated muscle fibers run in a cranial direction from the bulb of the penis to the base of the bladder along the anterior and lateral aspects of the prostate and the membranous urethra. Further dissection studies revealed that the rhabdosphincter is supplied by branches of the pudendal nerve after leaving the pudendal canal.

The surgical anatomy of needle bladder neck suspension

To define the surgical anatomy of needle bladder neck suspension in order to explain this operation's effect on urethral support and gain information useful in minimizing intraoperative complications. Needle bladder neck suspension was carried out on two unembalmed, multiparous cadavers. After fixing the suspensory sutures in place, the pelvis of one cadaver was completely dissected. The second cadaver was serially sectioned at 1-cm intervals, and the sections were subjected to both anatomic and histologic examination. These findings were correlated with the findings noted during an autopsy dissection of a woman who previously had undergone needle bladder neck suspension at our institution and with our surgical experience with this operation. The plane of dissection used to enter the space of Retzius lay between the vaginal mucous membrane and the visceral endopelvic fascia. The point of entry into the retropubic space lay between the levator ani muscles and its superior fascia, lateral to the arcus tendineus fasciae pelvis, the paraurethral vascular plexus, and bladder neck. It was cephalad to the perineal membrane (urogenital diaphragm). The paraurethral supporting tissues incorporated in the suspensory suture included the portion of the endopelvic fascia that lies between the vagina and urethra and, usually, the arcus tendineus fasciae pelvis. Attaching the suspensory sutures in needle bladder neck suspension seems to stabilize the bladder neck by providing a new point of lateral fixation for its supporting endopelvic fascia. Needle bladder neck suspension stabilized the supportive fascia of the urethra, and vascular injury may be minimized by detailed knowledge of paraurethral anatomy.

An unusual presentation of urinary retention

Patients with urinary retention frequently present to the emergency department (ED) for evaluation and treatment. Urinary retention is seen most often in males secondary to mechanical causes. However, other etiologies must be considered. We present an unusual case of a 35-year-old male who developed postcoital urinary retention secondary to urogenital diaphragm spasm.

Anal sphincter complex: endoanal MR imaging of normal anatomy.

To determine the normal anatomy of the anal sphincter complex on magnetic resonance (MR) images. Ten healthy volunteers (four men, six women; age range, 21-26 years) underwent MR imaging with an endoanal coil. The lower part of the anal canal contained the internal sphincter, the longitudinal muscle layer, and the external sphincter; the upper part comprised the internal sphincter, the longitudinal layer, and the puborectal muscle. At the upper end, the puborectal muscle was attached to the levator ani muscle. Anteriorly, the external sphincter was connected to the urogenital diaphragm; posteriorly, it was attached to the coccyx with the anococcygeal ligament. All perianal spaces were visible. The morphology of the anterior part of the external sphincter, different in men and women, was well displayed. Depiction of the anal sphincter complex on MR images is excellent.

Intrascrotal Epidermoid Cyst With Extension into the Pelvis

An 8-year-old boy presented with an asymptomatic extratesticular, scrotal epidermoid cyst with extension across the urogenital diaphragm into the pelvis. While routine contrast studies and ultrasound were performed, magnetic resonance imaging was most useful in depicting the anatomical boundaries of the lesion, including the intrapelvic extension. Complete excision was performed transcrotally. The lesion is histologically indistinguishable from epidermoid cysts found elsewhere in the external genitalia, that is the penis, scrotum or testis. The etiology is unknown but it may represent a monolayer teratoma of germ cell origin or abnormal embryological closure of the median raphe.

Cobb's collar

Over a 3-year period 128 boys had endoscopic video recording; 29 were found to have a localized constriction of the bulbar urethra. Three had significant narrowing, 11 had a moderate change in lumenal diameter, and 15 had a minor indentation. Three boys had a membranous obstruction, 21 had a lesion that changed appearance during the endoscopy, consistent with contracting muscle, and 5 (all minor abnormalities) had a constriction of uncertain nature. Four also had an additional, more proximal membrane in the posterior urethra. Of the 23 boys with a Cobb's collar who had a urethrogram preoperatively, 18 were found to have an indentation in the bulbar urethra, separate from the external sphincter, which correlated in position with the cystoscopic findings. Most of the bulbar urethral lesions were incidental findings, which may represent either a muscular or fibrous remnant of the urogenital diaphragm.

Prostate cancer: Comparison of retrograde urethrography and computed tomography in radiotherapy planning

Purpose : To prospectively compare the role of retrograde urethrography and high-quality computed tomography during the treatment planning of patients with prostate cancer. Methods and Materials : Forty consecutive men with localized prostate cancer underwent planning computed tomography prior to simulation. At the time of simulation we performed retrograde urethrography and compared the location of the inferior border of the urogenital diaphragm to the location of the ischial tuberosities and the prostate and base of the penis as seen on the computed tomography scan. Results : Interobserver identification of the prostatic apex varied in 70% of the cases. Perhaps due to this variability, attempts to place the inferior border of the treatment field in relation to the prostatic apex resulted in an inadequate margin (< 1 cm) beneath the urogenital diaphragm in 5%. In contrast, placing the inferior border at the ischial tuberosities or the base of the penis as seen on computed tomography insured an adequate margin for all patients. The distance from the urogenital diaphragm to the ischial tuberosities and, thus, the potential margin beneath the urogenital diaphragm was > 2 cm in 77%, while the distance from the urogenital diaphragm to the base of the penis was ≥ 2 cm in only 43%. Conclusion : This demonstrates the difficulty in reliably identifying the prostate on computed tomography. Nevertheless, by identifying the base of the penis, planning computed tomography provides adequate information to cover the target volume, and results in minimal overtreatment of normal structures. Urethrograms are not necessary if the computed tomography is properly used or if the ischial tuberosities are used as a standard inferior border, but they can reduce the length of urethra in the treatment volume which could potentially reduce complications.

Radiographic appearance of the pars nuda urethrae in the voiding urethrogram.

The pars nuda is the most anterior segment of the male membranous urethra, extending from the urogenital diaphragm to the urethral bulb. It differs from adjacent urethral segments in being incompletely supported by corpus cavernosum and musculature. Usually, this part of the urethra is difficult to distinguish in a voiding urethrogram. Occasionally, however, it may stand out clearly in certain phases of urethral muscular activity, resulting in a roentgen picture which may mimic an abnormality.

Anatomy of cavernous nerves distal to prostate: microdissection study in adult male cadavers

Retrograde and antegrade dissections from the penile hilum to the prostatic area and the glans penis were performed in 4 formalin-preserved adult male cadavers. In addition to the medial branches accompanying the urethra, the lateral branches of the cavernous nerves pierced the urogenital diaphragm 4 to 7 mm from the striated muscles of the external sphincter. At the penile region, multiple communications between the cavernous and dorsal nerves were noted that suggest that either the cavernous nerves use the dorsal nerve as a carrier to the distal portion of the penis or the dorsal nerve may itself contain autonomic fibers. These findings will improve our ability to preserve erectile function during pelvic, urethral, and penile surgery.

Reconstruction of a Near Total Male Urethral Defect with a Microvascular Free Flap

We describe a new technique for reconstruction of a traumatic near total male urethral defect. With this procedure a microvascular free flap transfer of the radial forearm skin is used to create a 23cm. neourethra extending from the urogenital diaphragm to the glans of the penis. This single-stage transfer allows large traumatic wounds to heal, enables the patient to urinate while standing without strictures, and maintains urinary continence.

Prostate cancer: retrograde urethrography to improve treatment planning for radiation therapy.

Thirty men with clinical stage A or B prostate cancer underwent retrograde urethrography at the time of simulation. The inferior edge of the prostate apex was visualized as an abrupt narrowing of the column of contrast material at the urogenital diaphragm. The distance between the line connecting the lower poles of the ischial tuberosities and the site of abrupt narrowing of the column of contrast material (prostate apex) ranged from 0.2 cm to 2.9 cm (median, 1.5 cm). In eight of the 30 (27%) cases, this distance was less than 1.0 cm. In these patients, it would have been inappropriate to place the lower field edge at the bottom of the ischial tuberosities because this would have resulted in an insufficient margin (less than 1.0 cm) below the prostate apex. The authors quantify the percentage of patients who would not be adequately treated if the ischial tuberosities were used as the lower border of the treatment fields. The information obtained at retrograde urethrography can be used to place the inferior border of the treatment fields properly, at least 1.0 cm below the prostate apex.