UroToday.com – The annual Society for Urodynamics and Female Urology meeting was held on Saturday May 20 at the Omni Hotel adjacent to the Georgia World Congress Center. The theme of the 3 hour meeting was “The Urethra” with the first portion of the meeting dedicated to the discussion of the normal, non-pathologic urethra and the second half covering salient features, evaluation and therapy of the abnormal urethra.
The opening session was moderated by Firouz Daneshgari, M.D. and included several talks on various aspects of urethral anatomy and physiology. Larry Baskin, M.D. discussed his work in the study of the anatomy of the urethral sphincter in both males and females.
By studying the urethral sphincter morphology in fetal specimens as well as by using 3 dimensional imaging techniques Dr. Baskin and his group have been able to modify some of the classically held concepts regarding urethral anatomy. He outlined some of the differences in its structure and location in males and females as well as the influence of androgens in its development in the male. Alan Wein, M.D. gave a talk on emerging data regarding the pharmacology of the bladder outlet and urethra. It is now clear that the smooth muscle of the proximal urethra and bladder neck is under the influence of the sympathetic nervous system with alpha adrenergic receptors, specifically the _-1a receptor subtype, predominating in this region.
The role of beta adrenergic receptors at the bladder outlet remains undefined. There appears to be a role for nitric oxide (NO) as an inhibitory transmitter at the bladder outlet, probably under the influence of the parasympathetic nervous system. The extramural striated muscle of the urethra is not directly influenced by adrenergic stimulation, however, receptors at the level of Onuf’s nucleus in the sacral spinal cord can be modulated by adrenergic and serotonergic agents and therefore centrally acting pharmacologic agents can have an effect on urethral function.
Gary Lemack, M.D. summarized current methods of imaging the normal and abnormal urethra. He reviewed the use of MRI, ultrasound and standard cystourethrography. Given the rapid incorporation of newer imaging modalities, he made a strong argument that cystourethrography should not be dismissed as a passé study as, in the proper clinical setting, it is very much a clinical useful diagnostic tool.
Dr. Lemack emphasized that these all of these studies provide only anatomic information, and although certain inferences can be made regarding function, considerable caution should be utilized when trying to elucidate conclusions regarding function from static anatomic images.
Finally, Professor Werner Schaefer discussed various aspects of the biomechanics of urethral closure as they relate to urodynamic testing and therapy of stress incontinence. He emphasized that biomechanically, UPP is a poor diagnostic test with considerable limitations including the vast overlap between continent and incontinent individuals, the fact that the test itself is not performed during load/stress conditions and therefore may not be testing relevant parameters, and that even with stress UPP testing, the tools that we currently have do not allow precise and rapid sampling adequate to draw accurate conclusions regarding urethral function.
Dr Schaefer then reviewed 4 biomechanical components of the optimal surgical augmentation of sphincteric/urethral function, 1) it should act at the level of the sphincter, 2) it should be tension free at rest, 3) it should be elastic and 4) it should NOT increase urethral closure pressure. Finally he discussed current biomechanical modeling of the anatomy of the urethral sphincter especially as it applies to changes during bladder filling/storage and emptying.
The next section, Historical Perspectives on Urethral Function was moderated by Chris Payne, M.D.. Norman Zinner, M.D. presented on the origins of urodynamic testing, specifically the problems with hydrodynamic modeling of the urethra during tubular flow. He provided a wonderful recounting of his early collaboration with engineers, physicists and other medical specialists during his pioneering work in the development of urodynamic testing. Dr. Zinner emphasized that collaborative work was, and probably still is, the best mechanism for asking relevant scientific questions and seeking their solutions. He had demonstrated through these collaborative efforts that the normal urethra biophysically functions roughly equivalent to a 9F rigid tube despite its potential to distend to greater than 30F with placement of a sound or other urethral instruments.
Furthermore he discussed that the commonly used term of “urethral pressure” does not adequately or accurately describe the property of the urethra which provides resistance to the flow of urine (i.e. prevents stress incontinence). This property must take into account several factors including force, energy, resistance, and pressure.
Ed McGuire, M.D. then discussed uses and abuses, as well as limitations and utility of the concept of leak point pressure. He concluded that it probably not the best test but it is probably better than all the other available tests for urethral function.
Finally, Dr. Margot Damaser provided some background and historical perspectives on the use of animal models for the study of urinary incontinence. She reviewed the limitations and advantages of several animal models of urinary incontinence and emphasized that the essential limitation (other than anatomical translation of these models into humans) is that urinary incontinence implies the lack of intent to urinate, which of course, cannot be communicated by an animal. Thus all current surrogate functional animal models will always be limited by this.
The final section of the normal urethra portion of the program involved a debate on the best test to measure urethral function moderated by E. Ann Gormley M.D. Mark Slack, M.D., defended the Urethral Retro-resistance Profile (URP). This novel study uses a proprietary device to seal off the urethral meatus and then retrograde perfuse the urethral lumen at a standard rate. The perfusion pressure gradually increases until fluid flows into the bladder. The pressure at which fluid flows into the bladder is the URP. The test-retest reliability of this method has been established in normal patients but the operational characteristics do not allow it to sufficiently discriminate normal from abnormal as the overlap between stress continent and stress incontinent women with respect to the URP is quite broad. It does seem to correlate well with symptom severity in those with SUI however. Larissa Rodriguez, M.D. discussed the valsalva leak point pressure (VLPP), and much like Dr. McGuires discussion earlier in the program, concluded that it is a flawed test with considerable limitations, but remains better than the alternatives. Peter Sand, M.D. gave a discussion in defense of urethral pressure profilometry. He concluded that although VLPP was best for assessing SUI, resting urethral profilometry was optimal for identifying ISD and therefore was most useful as a tool to predict failure for certain surgical operations designed to treat stress incontinence which have suboptimal success rates in those with significant ISD (i.e. retropubic suspensions or transobturator tape procedures). Finally, Victor Nitti, M.D., reviewed the limitations of all of these methods of determining urethral function. He concluded that since none of them accounted for urethral hypermobility and its contribution to SUI, that they all were considerably flawed especially when trying to determine a numerical value to describe a cutoff for the physiological phenomenons of SUI and ISD.
Bill Steers, M.D. opened the second half of the program by providing an update of the ongoing NIH trials involving the Urinary Incontinence Treatment Network (UITN). The UITN now has 3 ongoing trials. No clinical outcomes data was provided for any of the trials as they are all either accruing patients or currently closed to new patients with data acquisition ongoing. The SISTEr trial compares Burch and sling for SUI at 2 years, the BE-DRI trial compares tolterodine alone to tolterodine plus behavioral modification for urge incontinence at 18 months, and the TOMUS trial compares retropubic to transobturator tapes for SUI at 1 and 2 years. Rodney Appell, M.D. then reviewed the ongoing AUA SUI Surgical Treatment of SUI Guidelines Panel. This update of the Guidelines published in 1997 is in the process of statistical analysis and involved the review of over 6800 SUI papers in the literature. When finished, data and recommendations regarding the use of slings, midurethral tapes, retropubic suspensions, laparoscopic suspensions, injectables and artificial urinary sphincters will be provided.
A series of point-counterpoint debates were then moderated by Raymond Rackley, M.D. The first debate involved the optimal management of the devastated female urethra between David Ginsberg, M.D. and Jerry Blaivas, M.D.
Dr. Ginsberg defended the application of transvaginal bladder neck closure with either a suprapubic tube or continent catheterizable stoma especially in those with neurogenic vesicourethral dysfunction and urethral destruction due to chronic indwelling urethral Foley catheters.
Dr. Blaivas described urethral reconstruction with a number of vaginal and labial rotational flap techniques and presented his impressive case series of such reconstructions. Sender Herschorn M.D. debated J. Christian Winters, M.D. on the optimal urethral bulking agent in 2006.
Dr. Herschorn took the position that although collagen is not the ideal agent, it has the best safety record, and no other agent has demonstrated superior efficacy or durability. Dr. Winters reviewed a number of newer agents including calcium hydroxylapatite, ethylene vinyl alcohol, dextranomer beads in hyaluronic acid and carbon coated zirconium beads and expressed some optimism that one of these agents, or perhaps an agent yet in the marketplace may one day demonstrate long term durability, efficacy and safety.
Finally, Shlomo Raz M.D. faced off against Duane Cespedes, M.D. in debating the merits of the male urethral sling for postprostatectomy incontinence (PPI). Dr. Raz started off by noting that despite the fact that he owns the patent for the male perineal bone anchored sling, he feels that the results of the surgery are inferior to that of the artificial urinary sphincter. He routinely performs the artificial urinary sphincter in place of the bone anchored sling. He gave a review of the history of fixed urethral resistance for the treatment of PPI including the Kaufman prosthesis, the Kaufman procedure and the Rosen prosthesis. He noted that he was the first author on the original paper on the Kaufman prosthesis, and that although the initial results were quite favorable; the long term durability of the procedure was poor requiring multiple reinjections, reoperations and explanations. He expressed considerable reservations regarding the sling in that the long term results of the male sling will likely be similar. Dr. Cespedes countered that the male perineal bone anchored sling is an effective procedure for the carefully selected patient. These include patients with mild incontinence and the absence of significant detrusor dysfunction. Patients with a history of radiation therapy are not excluded as being candidates for the procedure. He stated that the optimal technique for the bone anchored sling has not been defined and perhaps ongoing small refinements to the procedure may result in further improvements. He disagreed with Dr. Raz regarding the prospects of a poor long term durability of the sling similar to the Kaufman prosthesis. He stated that many of the Kaufman prostheses failed due to problems with anchoring, and that with ongoing refinements of the techniques of anchoring the male sling, surgeons will have improved results.
The final session of the 2006 SUFU meeting was a panel discussion entitled “Reoperative SUI Surgery: What I do and why I do it” moderated by Eric Rovner, M.D. Panelists included Roger Dmochowski, M.D., David Staskin, M.D., Carl Klutke, M.D. and Jacques Corcos, M.D. The first case presented was a patient with recurrent SUI following a failed cadaveric fascial sling. There was consensus among the faculty that pressure flow urodynamics (PFUDS) with or without video, as well as a cystoscopy would be indicated prior to consideration of reoperation. The panelists expressed that a midurethral tape procedure or injectable agent would likely be beneficial if the urodynamics were consistent with recurrent SUI. The second case was a young woman triathlete with urinary retention one month following a TVT. Of the panelists, only Dr. Staskin would have performed PFUDS prior to consideration of sling incision. The other panelists would have gone directly to sling incision in the OR however a straw poll of the audience suggested that there was an equal split regarding the need for preoperative PFUDS. The panelists quoted a range of recurrent SUI between 10-30% following incision. If the original TVT was done by the panelists, all agreed that sling incision would have been done earlier than 1 month, and Dr. Klutke went so far as to suggest intervention within the first few days of the surgery. The case was then altered such that the original surgery was an autologous fascial sling with urinary retention. The panel agreed that a longer period of waiting (longer than 1 month and probably up to 3 months) was indicated in this case. However, all panelists cautioned regarding the possibility of the development of chronic detrusor dysfunction with prolonged obstructive voiding. The third case was an individual with recurrent SUI following a Burch and transobturator sling with a low leak point pressure and an anatomically fixed urethra. The panel agreed on a complete preoperative evaluation including PFUDS, cystoscopy, voiding diary, pad test, and possibly upper tract imaging. If the evaluation was consistent with ISD, then an injectable agent was felt to be optimal however, Dr. Staskin suggested urethrolysis and autologous fascial sling was more likely to be a durable solution than an injectable. Finally a case of recurrent SUI following TVT was presented complicated by the incidental finding of a symptomatic urethral diverticulum. Three panelists would have performed the diverticulectomy first, followed by a sling at a later date, whereas one panelist preferred urethral diverticulectomy concomitant with a pubovaginal sling. None of the panelists would have replaced a synthetic sling at the time of urethral diverticulectomy.
By Eric S. Rovner, MD
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