An anatomical description of the male and female urethral sphincter complex

PURPOSE: We performed a detailed study of the lower urinary tract of the male and female human fetus to elucidate the anatomy of the urethral sphincter complex in both sexes and its relationship to the surrounding organs and tissues. MATERIALS AND METHODS: A total of 12 male and 14 female normal human pelvic specimens ranging from 17.5 to 38 weeks of gestation were studied by serial sections and immunohistochemical analysis. Three-dimensional reconstructions were created from serial sections to demonstrate the anatomy of the lower urogenital tract and urethral sphincter in both sexes. Specific attention was directed to the sphincteric muscle of the urethra. RESULTS: The urinary continence mechanism is formed by a combination of detrusor, trigone and urethral sphincter muscles with distinctive histological characteristics in both sexes. In males the external urethral sphincter covers the ventral surface of the prostate as a crescent shape above the verumontanum, horseshoe shape below the verumontanum and crescent shape along the proximal bulbar urethra. The levator ani muscles form an open circle around the external sphincter with a hiatus at the ventral aspect. In females the external urethral sphincter covers the ventral surface of the urethra in a horseshoe shape. Caudally the same horseshoe-shaped external sphincter increases in size to envelop the distal vagina. The levator ani muscles do not support the proximal urethra. The smooth and striated muscle components of the urethral sphincter complex are inseparable in both sexes. CONCLUSIONS: The developmental anatomy of the urethral sphincter complex is analogous in both sexes. The male and female urinary sphincter mechanism is composed of detrusor, trigone and urethral muscles, each of different muscular origins. The levator ani does not surround the ventral aspect of the urethra and may not have an active role in continence in both sexes. This new concept in the anatomy of male and female sphincter morphology may help to refine our reconstructive and ablative surgical techniques.     

Urinary continence after repair of membranous urethral stricture in prostatectomized patients.

Prostatectomy by open or transurethral techniques usually destroys the function of the internal sphincter (bladder neck), which is the first line of defense against incontinence. Urinary continence then depends upon the intrinsic smooth muscle sphincter of the membranous urethra and the striated external sphincter. Unfortunately, a significant incidence of membranous urethral stricture occurs after a prostatic operation. Most such strictures can be managed with periodic dilatation but some are difficult and dangerous to dilate. Complications such as recurrent acute retention, bacteremia, false passages, stone formation, fistulas and so forth are indications for surgical cure of the stricture. However, can urethroplasty of the membranous urethra be carried out in these patients without inevitable incontinence? At our center 33 prostatectomized patients have had a 2-stage urethroplasty for refractory membranous urethral strictures. Nine patients had troublesome stress incontinence after the first-stage operation but only 4 of these had continuing incontinence after the second-stage operation. These patients had been noted to have transient postoperative stress incontinence after the prostatectomy. Although there is a risk of incontinence after urethroplasty of the membranous urethra in prostatectomized patients, the risk is sufficiently low that the operation should not be denied patients with refractory strictures in whom the only alternative eventually will be some form of urinary diversion.     

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 diaphram’ 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 diaphram’ is a myth. The standard technique of radical prostatectomy significantly damages the external sphincter.     

Combined external urethral bulking and artificial urinary sphincter for urethral atrophy and stress urinary incontinence

OBJECTIVE: To describe a technique of externally bulking the urethra with a soft-tissue graft before placing another artificial urinary sphincter (AUS), as when placing another AUS for recurrent male stress urinary incontinence (SUI) other manoeuvres, e.g. placing a tandem cuff or transcorporal cuff, must be used to obtain urinary continence in an atrophic urethra, and each is associated with morbidity. PATIENTS AND METHODS: From January 2003 to July 2004, five patients (mean age 74 years, range 62-84) treated by radical prostatectomy were referred for recurrent SUI after placing an AUS (four, including one with urethral erosion) or a male sling (one, with a resulting atrophic urethra). Each patient was treated with an external urethral bulking agent (Surgisis) ES, Cook Urological, Spencer, Indiana) and had an AUS placed. RESULTS: In each patient the greatest urethral circumference was <4 cm. To place a functional 4 cm cuff, the diameter of the urethra was enhanced by wrapping it with Surgisis ES. Continence was significantly improved in all patients except one 84-year-old man who had the replanted artificial sphincter removed because of erosion 14 months after surgery. CONCLUSION: In cases of severe recurrent SUI from urethral atrophy after placing an AUS, externally bulking the urethra with Surgisis ES before placing another AUS is well tolerated, and gives satisfactory results.     

Continence after radical cystoprostatectomy and total bladder replacement: a urodynamic analysis.

Urodynamic evaluation was performed in 10 patients after radical cystoprostatectomy and continent urethral diversion with detubularized ileum and in 13 patients continent after radical prostatectomy. In both groups surgical techniques were modified to optimize preservation of the periurethral tissue at the prostatic apex. For the ileal neobladder group 9 patients (90%) were completely continent and 1 (10%) noticed moderate nocturnal incontinence. The urethral sphincteric mechanism was well preserved in these patients, with no significant difference between the 2 groups in mean functional urethral length (3.8 +/- 0.6 versus 3.6 +/- 0.8 cm., p = 0.55) or maximal urethral closure pressure (87 +/- 34 versus 74 +/- 20 cm. water, p = 0.26). Tubularization of the bladder or neobladder above the level of the external sphincter was noted in both groups. Continence after radical cystoprostatectomy with continent urethral diversion and after radical prostatectomy is dependent upon an intact urethral sphincteric mechanism as well as a compliant, low pressure reservoir, either bladder or a bladder substitute. Urinary incontinence after total bladder replacement with detubularized ileum can be minimized by preserving as much of the distal urethral sphincter as possible. This can be done by careful dissection of the prostatic apex, performed under direct vision, with an understanding of the anatomy of the urethral sphincter and its innervation.     

保留尿控功能在耻骨后前列腺癌根治术的应用

目的:探讨保护耻骨前列腺韧带和保护尿道膜部括约肌群在耻骨后前列腺癌根治术后减少尿失禁的作用.方法:Ⅰ组32例前列腺癌按常规操作行耻骨后前列腺癌根治术,Ⅱ组32例前列腺癌采用保留耻骨前列腺韧带和尿道膜部括约肌群的方法行耻骨后前列腺癌根治术,术后1、3、6、12个月分别随访尿失禁情况.结果:两组年龄和PSA无显著差异,两组前列腺尖端切缘均无肿瘤残留,前列腺侧缘阳性率类似.Ⅱ组术后1、3、6个月尿控效果明显优于I组(P<0.05),但1年随访,Ⅰ组和Ⅱ组尿控效果类似.结论:在耻骨后前列腺癌根治术中保留耻骨前列腺韧带作用和尿道膜部括约肌群有显著提高近期尿控的效果,但1年随访两组尿控率无明显差异.     

FIXED AND DYNAMIC URETHRAL COMPRESSION FOR THE TREATMENT OF POST-PROSTATECTOMY URINARY INCONTINENCE: IS HISTORY REPEATING ITSELF?

PURPOSE: We reviewed the evolution of appliances and devices used for treating post-prostatectomy urinary incontinence. MATERIALS AND METHODS: We used the MEDLINE to search the literature from 1966 to March 2000 and then manually searched bibliographies to identify studies that our initial search may have missed. RESULTS: The evolution of treatment for post-prostatectomy urinary incontinence may be traced back to the 18th century. Two main schools of thoughts simultaneously evolved. The first fixed urethral compression devices were constructed to enable urethral obstruction by fixed resistance. This outlet resistance allows voiding after intra-abdominal and intravesical pressure is elevated but it is sufficient to prevent leakage between urinations. The other school of thought preferred creation of dynamic urethral compression in which outlet resistance is not fixed but may be decreased when voiding is desired or elevated between urinations. Therapeutic fixed and dynamic urethral compression interventions may be further divided into external or internal compressive devices or procedures. External fixed compression devices may be traced back to antiquity. A penile clamp, similar to the later Cunningham clamp, and a truss designed to compress the urethra by external perineal compression were presented in the Heister textbook of surgery, Institutiones Chirurgicae, as early as 1750. Dynamic compressive devices applied externally were developed much later, such as the first artificial urinary sphincter, described by Foley, in 1947 and the Vincent apparatus, described in 1960. The modern era of fixed urethral compression began in 1961 with Berry. Acrylic prostheses impregnated with bismuth to allow radiographic visualization were produced in various shapes and sizes, and used to compress the urethra against the urogenital diaphragm. In 1968 the University of California-Los Angeles group under the direction of Kaufman began to use cavernous crural crossover to compress the bulbous urethra (Kaufman I). Later 2 other modifications were described, including approximation of the crura in the midline using a polytetrafluoroethylene mesh tape (Kaufman II) and an implantable silicone gel prosthesis (Kaufman III). With the advent of the artificial urinary sphincter pioneered by Scott in 1973 interest in passive urethral compression disappeared in favor of the implantation of an inflatable circumferential prosthetic sphincter. Recently there has been a trend back to passive urethral compression. Synthetic bolsters have been described that passively compress the bulbar urethra to achieve urinary incontinence after radical prostatectomy. CONCLUSIONS: Much creativity has been dedicated to solve the complex and challenging problem of post-prostatectomy urinary incontinence. Devices used for treating this condition may be grouped according to the mechanism of action and how they are applied. Passive urethral compression, long abandoned in favor of dynamic implantable sphincters, has reemerged. Further research in this field may determine which school of thought may provide the best solution for treating post-prostatectomy urinary incontinence.     

Absence of urethral post-void milking: an additional cause for incontinence after radical prostatectomy?

OBJECTIVE: Urinary incontinence following radical prostatectomy is thought to be mainly due to stress leak as a result of sphincter insufficiency or detrusor dysfunction. However, a number of patients complain of stress-independent urinary leakage following voiding, i. e. a post-micturition dribble, of uncertain origin. In order to establish wether post-micturition dribble is related to altered post-void milking in the urethra, voiding cystourethrograms (VCUGs) were performed before and after radical prostatectomy and correlated with the presence of post-micturition dribble. METHODS: 23 VCUGs were recorded before and 19 VCUGs at 10-15 days following radical prostatectomy. A standard questionnaire regarding urinary symptoms was given to all patients pre- and postoperatively at defined intervals. RESULTS: 12 of 19 patients (63%) had post-void urethral milking prior to surgery, none of these reported post-micturition dribble. 6 of the 7 patients (86%) without post-void urethral milking reported post-micturition dribble. Postoperatively only 1 of 16 patients (6%) had post-void urethral milking. Of the 15 patients without postoperative urethral milking, 13 (87%) reported post-micturition dribble. The decrease in rate of milking and increase in rate of post-micturition dribble from before to after surgery was statistically significant (chi(2) test, p = 0.0001 and p<0.0001, respectively. CONCLUSIONS: These data suggest that post-void milk-out of the urethra is often absent in the early postoperative period after radical prostatectomy and that this is associated with post-micturition dribble. Aside from detrusor and sphincter dysfunction, urethral dysfunction, i.e. the absence of urethral post-void milking, seems to be an additional cause of incontinence following radical prostatectomy.     

Transvaginal ultrasound of urethral sphincter at the mid urethra in continent and incontinent women

PURPOSE: Few studies are available on imaging the urethral sphincter. We performed transvaginal ultrasonography to examine the muscle in continent and incontinent women. MATERIALS AND METHODS: Transvaginal ultrasonography was performed using a 7.5 MHz. transrectal probe in 19 continent and 69 incontinent supine women. Incontinent cases were classified as urge (14) and stress (55), and included urethral hypermobility (22) and intrinsic sphincter deficiency (33). Cadaver specimens were also examined to confirm the anatomy of ultrasound images. RESULTS: Transvaginal ultrasonography showed the urethra as a round structure consisting of a relatively high echogenic central zone and a relatively low echogenic peripheral zone. Matching ultrasound images with the anatomy of cadaver specimens indicated that the peripheral zone represents rhabdosphincter most reliably at the lateral aspects. Thus, its thickness was measured at the 9 o'clock position of the mid urethra. Mean thickness plus or minus standard error of mean was significantly decreased in stress incontinence compared with continence and urge incontinence (2.14 +/- 0.04, 2.78 +/- 0.08 and 2.87 +/- 0.11 mm., respectively, p <0. 001), while in intrinsic sphincter deficiency it was thinner than in hypermobility (2.00 +/- 0.05 versus 2.35 +/- 0.06 mm., p <0.01). There was no difference in central zone thickness according to continence status. CONCLUSIONS: Urethral structures may be visualized by transvaginal ultrasonography. The rhabdosphincter image was thinner in stress incontinence, especially in intrinsic sphincter deficiency. Transvaginal ultrasonography may be a useful clinical test for examining the morphology of the urethral sphincter muscle in women.     

Studies on the sphincteric system located distally in the urethra: the external urethral sphincter revisited

Anatomical, physiological and clinical studies were done on the sphincteric system located distally in the male urethra. Results revealed that urinary continence after radical transurethral prostatectomy is attributed to the true external urethral sphincter, which is defined anatomically as intrinsic striated muscle of the urethra. Urodynamic and electrophysiologic data suggested that this external sphincter is influenced directly and more predominantly by the autonomic alpha-adrenergic system than by the somatic innervation system. Clinical experiences in the management of external sphincter disorder in neurogenic vesical dysfunction by pharmacologic manipulation of the alpha-adrenergic system were presented. A plea is made for consideration of this revised concept of the external sphincter in understanding various pathophysiology of the lower urinary tract.     

Anatomical landmarks of radical prostatecomy

INTRODUCTION: In the present study, we review current literature and based on our experience, we present the anatomical landmarks of open and laparoscopic/endoscopic radical prostatectomy. METHODS: A thorough literature search was performed with the Medline database on the anatomy and the nomenclature of the structures surrounding the prostate gland. The correct handling of puboprostatic ligaments, external urethral sphincter, prostatic fascias and neurovascular bundle is necessary for avoiding malfunction of the urogenital system after radical prostatectomy. RESULTS: When evaluating new prostatectomy techniques, we should always take into account both clinical and final oncological outcomes. The present review adds further knowledge to the existing "postprostatectomy anatomical hazard" debate. It emphasizes upon the role of the puboprostatic ligaments and the course of the external urethral sphincter for urinary continence. When performing an intrafascial nerve sparing prostatectomy most urologists tend to approach as close to the prostatic capsula as possible, even though there is no concurrence regarding the nomenclature of the surrounding fascias and the course of the actual neurovascular bundles. After completion of an intrafascial technique the specimen does not contain any periprostatic tissue and thus the detection of pT3a disease is not feasible. This especially becomes problematic if the tumour reaches the resection margin. DISCUSSION: Nerve sparing open and laparoscopic radical prostatectomy should aim in maintaining sexual function, recuperating early continence after surgery, without hindering the final oncological outcome to the procedure. Despite the different approaches for radical prostatectomy the key for better results is the understanding of the anatomy of the bladder neck and the urethra.     

Normal anatomy of urethral sphincter complex in young Chinese males on MRI

Purpose

In this research, the normal anatomy of urethral sphincter complex in young Chinese males has been studied.

Methods

The sagittal, coronal, and axial T2-weighted non-fat suppressed fast spin-echo images of pelvic cavities of 86 Chinese young males were studied.

Result

Urethral sphincter complex is a cylindrical structure surrounding the urethra and extending vertically from bladder neck to perineal membrane. Urethral striated sphincter covers the anteriolateral urethra like a hat from bladder neck to verumontanum, while it surrounds the urethra in a ring shape from verumontanum to perineal membrane and backwards ends in central tendon of the perineum. From bladder neck to perineal membrane, the thickness of urethral smooth sphincter decreases gradually, and it extends forward to surround urethra with urethral striated sphincter as a ring. The length of urethral striated sphincter is 12.26–20.94 mm (mean 16.59 mm) at membranous urethra: 27.88–30.69 mm (mean 28.99 mm) from verumontanum to perineal membrane. The thickness of striated sphincter at membranous urethra is 4.29–6.86 mm (mean 5.56 mm) for the muscle of the anterior wall and 2.18–2.34 mm (mean 2.26 mm) for the muscle of the posterior wall.

Conclusions

In this paper, we summarized the normal anatomy of urethral sphincter complex in young Chinese males with no urinary control problems.     

Preservation of the smooth muscular internal (vesical) sphincter and of the proximal urethra during retropubic radical prostatectomy: Description of the technique

We describe our technique for preservation of the smooth muscular internal (vesical) sphincter and proximal urethra during radical retropubic prostatectomy. The first steps of the prostatectomy reflect the standard retropubic prostatectomy; whereas for the final phases, the procedure continues in an anterograde manner with incision of the fibers of the detrusor muscle at the insertion of the ventral surface of the base of the prostate. At this level, the inner circular muscle of the bladder neck forms a sphincteric ring of smooth muscle that covers the longitudinally‐oriented smooth muscle component of the urethra that extends distally to the verumontanum; these two proximal structures represent the internal sphincter that envelops and locks the proximal urethra. A blunt dissection is continued until the ring‐shaped vesical sphincter is separated from the prostate and the longitudinally‐oriented smooth muscle component of the urethral musculature is identified. The base of the prostate is then gently separated from the urethra and from the bladder until the maximal length of the urethral musculature is isolated and preserved. Finally, a urethra‐urethral anastomosis is carried out and the ventral stitches are placed through the circular fibres of the bladder neck. In all cases we carry out circumferential biopsies of the proximal urethra and of the base of the prostate. The described technique is a feasible and safe method for preservation of the internal urethral sphincter. Despite the enthusiasm regarding our positive functional results, further studies with larger series are required to confirm these findings.     

Basic principles of anatomy for optimal surgical treatment of prostate cancer

The treatment of prostate cancer (PCa) with nerve sparing radical prostatectomy (NSRP) has experienced a substantial improvement in recent years due to new insights in anatomy of the prostate and of the adjacent structures. Knowledge of this specific anatomy is mandatory during RP in order to avoid injuries to functional tissue. Above all, these tissues are the neurovascular bundle (NVB) and the urethral sphincter. We therefore reviewed the available literature on prostatic anatomy and summarized it in this article. A search of the PubMed database was performed using the keywords radical prostatectomy, anatomy, neurovascular bundle, fascia, pelvis and sphincter. Relevant articles were reviewed, analyzed and summarized. This article gives an insight in the anatomy of the NVB, the urethral sphincter and the fascias surrounding the prostate. The NVB might be hampered near the seminal vesicles, at the lateral surface of the prostate and in the area of the prostato-urethral junction. The urethral sphincter might be hampered during dissection of the dorsal vein complex and during dissection of the urethra at the prostatic apex. Finally, the anatomy of the fascias surrounding the prostate is complex and can inter-individually vary substantially, which adds to the technical difficulties of NSRP. With this article we provide an overview on the complex anatomy of the prostate and the adjacent tissues. Respecting and considering these anatomic principles during NSRP should result in good postoperative functional outcome, as well as in good outcome in cancer control.     

The development of the external urethral sphincter in humans

OBJECTIVE: To assess the hypothesis that during fetal development, the external urethral sphincter changes from a concentric sphincter of undifferentiated muscle fibres to a transient ring of striated muscle which regresses caudo-cranially in the posterior urethra during the first year of life, when the sphincter assumes its omega-shaped configuration. MATERIALS AND METHODS: The anatomy and development of the external urinary sphincter was assessed in human males and females during fetal life. Plastic-embedded sections (transverse, sagittal and frontal planes; 300-700 microm) of the pelvis of 31 females and 31 males (9 weeks of gestation to newborn) were stained with azure II/methylene blue/basic fuchsin and viewed at x 4-80. The sections of interest were taken from the bladder neck to the perineum. The sections of the membranous urethra were reconstructed three-dimensionally using a computer program. RESULTS: In both male and female an omega-shaped external sphincter was apparent in all specimens at > 10 weeks of gestation. In the early fetal period (ninth week), there was undifferentiated mesenchyme; in this period the mesenchyme was more dense in the anterior part and loose in the posterior part of the urethra. In females, there was a close connection between the urethra and the anterior wall of the vagina. CONCLUSION: The omega-shaped configuration of the external urethral sphincter was recognisable from 10 weeks of gestation in both sexes. There was no suggestion of a change from a cylindrical to an omega-shaped sphincter in the fetal period to birth. Also, a transient 'tail' posterior to the sphincter was not apparent. The rectovesical septum was well developed in neonates. There is no reason to assume that the development of the septum leads to an apoptosis of muscle cells in the posterior part of the external sphincter in males after birth. The anatomical development of the external sphincter does not explain transient outlet obstruction during fetal life. The function of the muscle may change during development because of neuronal maturation.     

Experiences with a new method of surgery for incontinence]

Our new operation method against the prostatectomy-incontinence is only indicated, if the external urethral sphincter is intact. This possible in 90% of all incontinent patients after prostatectomy. In this situation we can guarantee a good chance of success. An interoperative lesion of the bulbi arteries, which enter in the urethra through the posterior portion of the bulbocavernosus muscle, must be prevented. A lesion of them leeds to a total necrosis of the posterior urethra.     

Urinary incontinence after treatment for localized prostate cancer

The incidence of incontinence after radical prostatectomy has ranged from 0 to 57% depending on the series and the type of incontinence considered. When total incontinence (not minimal stress incontinence) is reported, the average incidence is no more than 5%. This figure will increase with age, and in most series, approximately 10% of patients around the age of 70 will have total incontinence postoperatively. Preservation of continence after radical prostatectomy depends largely on the preservation of the distal urethral smooth-muscle sphincteric mechanism, which begins at the pelvic floor and ends at the prostatourethral junction. Newer techniques that attempt to increase postoperative continence include not cutting the puboprostatic ligaments and attempting to preserve as much striated muscle as possible along the length of the remaining urethra. Patients who are incontinent for 6 months after the surgery with no evidence of improvement will probably not become continent on their own. Therefore, some type of therapy should be considered. The options are periurethral injection of a bulking agent, implantation of an artificial sphincter, and, most recently, a bulbourethral sling procedure.     

A study of the continence mechanism of the external urethral sphincter with identification of the voluntary urinary inhibition reflex

PURPOSE: The role of the external urethral sphincter in the opposition and interruption of the act of voiding was investigated. MATERIALS AND METHODS: The study included 7 men and 5 women with a mean age plus or minus standard deviation of 38.6 +/- 11.2 years. The bladder was filled with saline up to the urge sensation. Detrusor and posterior urethral pressures were recorded before and upon resisting the reflex detrusor contraction, and upon interrupting voiding by voluntary external urethral sphincter contraction. The test was repeated by interrupting the urinary stream with external urethral sphincter electrostimulation. The electromyography response of the internal urethral sphincter to the suppression and interruption of voiding was documented before and after internal urethral sphincter anesthetization. RESULTS: Suppression of the reflex detrusor contraction as well as of urinary stream interruption by external urethral sphincter contraction voluntarily or by electrostimulation resulted in a significant detrusor pressure decrease (p <0.01) and urethral pressure increase (p <0.001). Internal urethral sphincter electromyography activity, which normally disappears during voiding, was still present. After internalurethral sphincter anesthetization subjects suppressed the reflex detrusor contraction by voluntary external urethral sphincter contraction for a mean of 62.6 +/- 9.6 seconds, after which involuntary voiding occurred. The internal urethral sphincter showed no electromyography activity. CONCLUSIONS: The external urethral sphincter induces continence by preventing internal urethral sphincter relaxation at the detrusor contraction, which is suggested to be reflex in nature and is called the voluntary urinary inhibition reflex, and by mechanically compressing the urethra. Contraction of the external urethral sphincter, which is a striated muscle, mechanically occludes the urethra for a few seconds, by which time the detrusor has relaxed as an effect of the voluntary inhibition reflex.     

Urodynamic Assessment of Urethral Sphincter Function In Post-Prostatectomy Incontinence

Purpose

Direct measurement of maximum urethral pressure by urethral profilometry has been used widely to assess urethral sphincter function. We attempted to determine if there was any relationship between maximum urethral pressure, which is measured at the level of the membranous urethra, or extrinsic urethral sphincter function, and the amount of abdominal pressure needed to cause leakage (abdominal leak point pressure) in men with post-prostatectomy incontinence. We also examined the relationship between external sphincter function and continence or incontinence.

Materials and Methods

We retrospectively evaluated fluoro-urodynamics performed in 37 men with post-prostatectomy incontinence. Urodynamic study consisted of measurement of maximum urethral and abdominal leak point pressures, and assessment of extrinsic sphincter function by pressure measurements and radiographically.

Results

Data were analyzed on 27 patients for whom abdominal leak point and maximum urethral pressures were available. Mean maximum urethral pressure was 52.5 cm. water (range 20 to 165) and mean abdominal leak point pressure was 77.8 cm. water (range 27 to 132). Regression analysis was performed between maximum urethral and abdominal leak point pressures. A Pearson correlation coefficient of 0.13834 was calculated (p = 0.4914) indicating virtually no correlation between the 2 measurements in our sample. Extrinsic urethral sphincter was normal in all patients. Only 1 of 37 patients had no evidence of intrinsic sphincter deficiency, that is there was no urine leakage with increases in abdominal pressure and the patient was incontinent solely based on bladder dysfunction (detrusor instability).

Conclusions

Our study indicates that incontinence after prostatectomy due to an increase in abdominal pressure (stress incontinence) does not depend on extrinsic sphincter function and is not related to maximal urethral pressure. We conclude that post-prostatectomy incontinence due to sphincter dysfunction results from intrinsic sphincter deficiency. In our experience bladder dysfunction is rarely the sole cause of post-prostatectomy incontinence.     

INEFFICIENT URETHRAL MILKING SECONDARY TO URETHRAL DYSFUNCTION AS AN ADDITIONAL RISK FACTOR FOR INCONTINENCE AFTER RADICAL PROSTATECTOMY

PURPOSE: Continence after radical prostatectomy is thought to depend completely on the striated urethral sphincter. However, some patients complain only of occasional post-void dribbling. Therefore, we determined whether urethral dysfunction may be another cause of incontinence. MATERIALS AND METHODS: The sensory threshold of electric stimulation was measured by double ring electrodes in the membranous urethra and 2.5 cm. distal in 29 men before and in 29 after radical retropubic prostatectomy. In addition, voiding cystourethrography was performed in 66 patients before and in 49 after surgery to determine complete post-void urethral emptying or milking. RESULTS: The mean sensory threshold of the membranous urethra was 15 +/- 3 mA. preoperatively versus 38 +/- 17 postoperatively (p <0.0001). The sensory threshold 2.5 cm. further distal was 12 +/- 5 mA. before and 10 +/- 4 after radical prostatectomy, which was not statistically significant. Postoperatively in completely continent patients and in those with dribbling the mean threshold was 32 +/- 12 and 43 +/- 18 mA. in the membranous urethra (p = 0.09), and 11 +/- 4 and 9 +/- 4 mA. in the bulbar urethra, respectively, which was not statistically significant. Of the 66 patients 36 (55%) showed post-void urethral milking before surgery but only 8 of 49 (16%) showed it postoperatively (chi-square test p <0.0001), including 7 who were completely continent and 1 who complained of occasional post-void dribbling. CONCLUSIONS: After radical prostatectomy sensitivity of the membranous but not of the bulbar urethra is affected, correlating with postoperative continence. In addition, post-void dribbling seems to be associated with the loss of urethral milking. We conclude that preserving urethral function is another important continence factor after radical prostatectomy.