Clinical and urodynamic evaluation of the polypropylene (marlex) sling for genuine stress incontinence

Ten women undergoing a polypropylene suburethral sling procedure for treatment of genuine stress incontinence were assessed pre- and post-operatively by standard urodynamic methods and by urethral pressure profile measurements at rest and on stress. Eight patients were subjectively and seven objectively cured of stress incontinence. A significant reduction in urine flow rate was found although this appeared to be of little relevance to the successful outcome of surgery. An increase in resting urethral profile length was seen in both successful and unsuccessful cases. The former also had an improvement in maximum urethral closure pressure on stress due to improvement in pressure transmission in the proximal three quarters of the functional urethral length. The urethra appeared relocated in a retropubic position following successful and unsuccessful operations. It is likely that failure was associated with periurethral fibrosis causing failure of pressure transmission despite adequate elevation.     

Mechanism of continence after modified Pereyra bladder neck suspension. Prospective urodynamic study

Twenty females with genuine stress urinary incontinence who underwent modified Pereyra bladder neck suspension were urodynamically studied pre- and postoperatively in an attempt to determine the mechanism by which continence was restored. Detailed analysis demonstrated no significant change comparing the pre- and postoperative cystometry findings, uroflow parameters, maximal voiding pressure, urethral resistance, maximal urethral closure pressure, or functional urethral length. The only significant change identified as a result of the surgical procedure was an alteration of proximal urethral pressure transmission during stress from negative to positive gradients. It is concluded that the modified Pereyra bladder neck suspension restores continence by restoring proper urethral support with restoration of positive pressure transmission to the proximal urethra without causing outflow obstruction, changing functional length, or altering maximal urethral closure pressure.     

Comparison of preoperative and postoperative pressure transmission ratio and urethral pressure profilometry in patients with successful outcome following the vaginal wall patch sling technique

AIMS: We studied preoperative and postoperative pressure transmission ratio (PTR) and urethral pressure profilometry in patients undergoing the vaginal wall patch sling technique as a first surgical approach for genuine stress incontinence (GSI) with urethral hypermobility. The specific aims were to determine the exact urodynamic parameters, if any, that may be improved postoperatively and to report the urodynamic outcome of the vaginal wall patch sling technique in successful cases. METHODS: Preoperatively, all patients had a positive standing stress test, urethral hypermobility on Q-tip testing, and normal postvoid residual volume. On urodynamics, all patients had equalization of maximum urethral closure pressure (MUCP) on cough profilometry, and absence of detrusor contractions on subtracted cystometry. The PTR for each cough was calculated. Cough spikes were assigned locations in the first, second, third, or fourth quartile of the functional urethral length (FUL). Urethral pressure profilometry was performed at bladder capacity in the sitting position. All urodynamic tests were repeated 3-6 months postoperatively. A two-tailed t-test was used for statistical analysis. RESULTS: Forty-eight patients demonstrated successful outcome at initial follow up and constituted the study population. There was a statistically significant increase in MUCP at stress as well as a statistical increase in PTR in the first, second, and third quartiles of the FUL postoperatively. CONCLUSIONS: The vaginal patch sling technique appears to restore continence both by buttressing the urethra at times of stress as well as repositioning the proximal urethra into the intra-abdominal pressure zone, thus, enhancing pressure transmission to the proximal urethra.     

Urethral closure function in women with prolapse

In 19 patients with different types of severe descensus, all without clinical evidence of stress incontinence, urethral stress pressure profiles and stress tests were done before and after repositioning of the prolapse. In 13 of the 19 patients, continence was artificial, because during repositioning they showed leakage of urine; however, 6 of the patients remained continent. The pressure transmission ratios decreased in different parts of the urethra in all the patients when repositioning with a gynecological speculum was done. The drop was most significant in those patients who lost urine after repositioning, showing poor urethral function. In women with genito-urinary prolapse, a test of urethral function is essential, even if there is no clinical evidence of incontinence after removal of the descensus. In cases of severe stress incontinence under this condition, a procedure for bladder neck stabilization should be added to routine prolapse surgery.     

Internal urethrotomy in girls and its impact on the urethral intrinsic and extrinsic continence mechanisms

The cause of incontinence in a group of 11 girls (mean age 18 +/- 3 years) who had undergone internal urethrotomy during childhood was assessed. Urodynamic methods were used to characterize the detrusor, and urethral profiles were performed to identify the impact of the operation on the extrinsic and intrinsic mechanisms of urethral closure. The results show that 4 of 11 patients demonstrated detrusor instability associated with a high voiding flow rate. The average resting urethral closure pressure in all patients showed significant reduction in maximum closure pressure (62 +/- 32 cm. water) when compared to normal age-matched controls. Transmission pressures to coughing demonstrated a high percentage of transmission to the distal and mid urethra (180 +/- 20 per cent). It was concluded that the intrinsic mechanism of urethral continence as measured by the resting urethral pressure profile was compromised by the urethrotomy. However, the extrinsic mechanisms as measured by the transmission values was not affected. On the basis of these findings it is argued that internal urethrotomy compromises the closure mechanisms intrinsic to the urethra. Continence in these patients most likely is maintained by the action of extrinsic factors transmitting high closure pressures at the distal third of the urethra. Finally, it is postulated that urethrotomy patients are at increased risk for stress incontinence at an early age.     

Urethral pressure and pressure variations in stress incontinent women and women with unstable detrusor

The urethral pressure and pressure variations were studied in ten genuine stress incontinent women and twenty-six women with unstable detrusor based on 1 hour recordings. In the stress incontinent women the mean maximum urethral pressure (mMUP) calculated from 1 hour continuous urethral pressure recordings was 49 cm H₂O and the mean maximum urethral closure pressure (mMUCP) was 38 cm H₂O. When analysed in relation to previous data from healthy women the mMUP and the mMUCP were significantly reduced. The urethral pressure variation (UPV) is a normal physiological activity of the urethra, also occurring in stress incontinent and unstable detrusor patients. The UPV amplitude of the stress incontinent women was reduced, indicating that the UPVs are related to the baseline pressure in urethra but still part of the complex pathophysiological changes occurring in urethra during stress incontinence. In the unstable detrusor group the parameters were within the range of the normal material except for the abrupt urethral pressure drop followed by detrusor contraction. However, these events were clearly different from the rhythmic urethral pressure variations which seem to discern from the pathogenesis of the unstable detrusor.     

Low urethral pressure and stress urinary incontinence in women: risk factor for failed retropubic surgical procedure

Nineteen women with stress urinary incontinence (SUI) and low urethral pressure were compared with 106 patients with SUI and normal urethral pressure. All underwent either a revised Pereyra procedure or Burch retropubic urethropexy, and all had detailed clinical and urodynamic evaluations before their operation and one year postoperatively. Surgical procedures effectively stabilized the bladder base and enabled adequate abdominal pressure transmission to the urethra in both groups of women. In spite of these urodynamic findings, the failure rate in women with stress urinary incontinence and low urethral pressure was significantly higher compared with women with good urethral pressure (50% vs 23% for the Pereyra procedure and 33% vs 12% for the Burch procedure [p less than 0.05]), indicating an etiology for their incontinence other than poor support to the urethrovesical junction; therefore, the need for another approach to cure stress incontinence.     

The effect of midodrine and its active metabolite ST 1059 on the human urethra in vitro and in vivo

The directly acting alpha-receptor agonist midodrine is active through its metabolite ST 1059. The effects of ST 1059 were investigated in vitro on strips of human urethra and on small human omental arteries. ST 1059 was as potent as noradrenaline on the isolated urethra, but had only 40% of noradrenaline's maximum activity. In omental arteries noradrenaline was at least ten times more potent than ST 1059 which only had about one fourth of noradrenaline's maximum activity. Compared to its effect on the vessels ST 1059 was ten times more effective on the urethra, whereas noradrenaline was slightly more effective on the vessels than on the urethra. Thus, in vitro St 1059 exhibited some selectivity for urethral alpha-receptors. When midodrine was given to 13 female patients with stress incontinence in the doses 2.5 mg and 5 mg x 3 for two weeks, only two had a positive urethral closure pressure during treatment and were subjectively improved. There were no effects on blood pressure and heart rate; one patient complained of pilo-erection. Two further patients received 7.5 mg x 3 for two weeks; both were subjectively improved but complained of pronounced pilo-erection. Only one of them had a positive urethral closure pressure during treatment. Blood pressure or heart rate did not change. Although it cannot be excluded that midodrine can increase intraurethral pressure with minor effects on blood pressure, it seems as the doses needed cause pilo-erection to an extent that limits the clinical usefulness of the drug.     

Role of striated and smooth muscle components in the urethral pressure profile in traumatic neurogenic bladders: a neuropharmacological and urodynamic study. Preliminary report

Urodynamic investigations with urethral pressure profile, and vesical, intrarectal and anal pressure recordings were performed in 37 patients with spinal cord lesions. The recordings were done before and after phentolamine injections and/or pudendal nerve blocks to evaluate the respective contribution of sympathetic and somatic innervation to the maximum urethral closure pressure in the mid and distal portions of the membranous urethra. A pressure gradient was demonstrated in the membranous urethra with higher values in the distal than in the mid portion. These results emphasize that the interrupted withdrawal technique is superior to the continuous technique in patients with upper motor neuron bladders. Mid urethral striated and smooth muscle components were shown to represent approximately 60 and 30 per cent of the maximum urethral closure pressure, respectively. In the distal urethra striated and smooth components are more abundant than in the mid portion and contribute in equal proportion to the maximum urethral closure pressure. No substantial role was found for the vascular bed in the maximum urethral closure pressure. The greatest pressure decrease in the mid and distal urethra of patients with lower motor neuron bladders was believed to be an effect of denervation supersensitivity. The results of pudendal blocks showed sphincter dyssynergia to be mediated through pudendal nerves via spinal reflex arcs. Phentolamine effects on bladder activity suggest that blockade of alpha-adrenergic receptors inhibits primarily the transmission in vesical and/or pelvic parasympathetic ganglia and acts secondarily through direct depression of the vesical smooth muscle. Our neuropharmacological results raise strong doubts as to the existence of a sympathetic innervation of the striated urethral muscle in humans.     

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.     

The effect of alpha-adrenergic stimulation in stress incontinence.

The urethra is innervated by adrenergic fibres and its smooth muscle is equipped mainly with alpha-adrenoreceptors. Norephedrine chloride, which is an alpha-stimulating agent, has been proposed as therapy for stress incontinence, since it was shown to increase the maximum urethral pressure at rest. For further study of the effect of norephedrine chloride on the urethal closure pressure at rest and in a dynamic situation, we examined ten severely stress-incontinent women before and after three weeks of treatment with this agent (100 mg by mouth twice daily). The urethral closure pressure at rest, between coughs of varied strength and at the precise moment of stress were recorded. The margin to leakage, the tone of the urethral wall and the transmission of pressure from abdomen to urethra were also among the estimated factors. No improvement was found in any of these respects. Alpha stimulation in this form therefore seems ineffective in severe stress incontinence and is not an alternative to surgical treatment.     

Urethral profilometry in women with uterovaginal prolapse

The aim of the study was to investigate the continence mechanism in women with uterovaginal prolapse by analysing urethral pressure profiles. Twenty-four women (mean age 59.0±11.9 years, mean parity 3.1±1.6) with prolapse underwent urodynamic evaluation. Urethral pressure profiles were obtained with prolapse and after reduction of the prolapse with a swab stick in the posterior vaginal fornix. After reduction the maximum urethral closure pressure (MUCP) and pressure transmission ratios (PTR) in all four quartiles of the urethra decreased, the position of the MUCP was shifted proximally and the functional urethral length was increased. Thirteen women reported a history of continence and 11 reported incontinence. Ten of 13 women (77%) who reported continence with prolapse were incontinent with their prolapse reduced. In these women, MUCP and PTRs in the first three quartiles of the urethra decreased significantly upon prolapse reduction. In the patients who reported incontinence with prolapse, only the MUCP decreased significantly upon prolapse reduction. Comparisons between the historically continent and incontinent women showed a statistically significant difference only for PTRs in the second and third quartiles of the urethra before prolapse reduction. Because the position of maximum urethral closure pressure before reduction was located in the distal half of the urethra in all patients, we conclude that direct pressure of the prolapsed mass on the urethra (rather than kinking) is the mechanism masking incompetence of the urethral closure mechanism in women with uterovaginal prolapse. The 77% rate of latent incontinence in this series suggests that women with severe pelvic relaxation should undergo careful urogynecologic evaluation before an attempt at surgical correction.Editorial Comment: Masked incontinence associated with genital prolapse is a well known problem for urogynecologists. The causes for this finding, e.g. kinking or compression, are not yet clear. The present study supports the compression theory. To gain a better understanding in the future, two points are important: to find a standard procedure for prolapse repositioning (pessary v speculum v swab stick) and to combine functional and radio- or sonomorphological findings in order to see whether compression and/or kinking occurs and with what consequences.     

Subjective and objective effects of intravaginal electrical myostimulation and biofeedback in patients with genuine stress urinary incontinence.

A group of 36 patients (18 premenopausal and 18 postmenopausal), all suffering from genuine stress urinary incontinence, underwent conservative treatment with 6 sessions of intravaginal electromyostimulation followed by 6 sessions of biofeedback; 89% of patients reported an improvement, 5.5% considered themselves cured and 5.5% reported no change. Intravaginal pressure measured before and after therapy increased by an average of 11 cm H2O in premenopausal patients and 17 cm H2O in the postmenopausal group. Intravaginal pressure increased in all patients and, according to maximal urethral closure pressure, this increasing intravaginal pressure was observed even in patients with low pressure urethras. The urodynamic factors studied were functional length, maximum urethral closing pressure and pressure transmission, together with urethral surface at rest and during stress, and residual surface. No significant changes were noted before and after treatment. The excellent subjective results contrast with the absence of improvement in these values.     

Effects of selective autonomic and pudendal denervation on the urethral function and development of retention in female dogs

PURPOSE: This trial is an experimental approach to the possible causes of continence and voiding problems after urethra sparing radical cystectomy and orthotopic bladder substitution in women. MATERIALS AND METHODS: Between January 1996 and January 1999 we included 24 mongrel female dogs in this 4-phase study of 6 dogs each. The effects of autonomic denervation of the urethra (phase 1) and urethral transection just distal to the bladder neck (phase 2) on the urethral pressure profile were recorded. In phase 3 the effects of autonomic denervation, urethral transection and pharmacological manipulation of the denervated transected urethra on the urethral pressure profile were studied in succession. In phase 4 the effects of pudendal nerve transection and pharmacological blockade were recorded. In the 12 phases 2 and 3 dogs the transected urethra was re-anastomosed to the bladder neck. Acute experiments were repeated after 2 and 6 months, urethrocystoscopy was done and post-void residual urine was estimated. Two of the latter dogs were sacrificed 6 months after the acute experiment and the urethras were histopathologically examined. RESULTS: Autonomic denervation resulted in a 46% to 48% decrease in mean maximal pressure in the proximal urethra in phases 1 and 3 (p <0.001) with no significant effect on the distal urethra. Urethral transection in phase 2 did not affect the urethral pressure profile. Phentolamine injection after urethral denervation and transection in phase 3 produced a further reduction of 11.3% and 46.3% in mean resting pressure in the proximal and distal urethra, respectively, while succinyl choline produced a 38.1% further decrease in the distal urethra. Unilateral and bilateral pudendal denervation reduced pressure in the distal urethra significantly but not in the proximal urethra. When phentolamine was given thereafter, a further decrease of 38% and 2.4% resulted in resting pressure values in the proximal and distal urethra, respectively. The change in distal urethral pressure was marginally significant after succinyl choline injection (p = 0.05). Results were reproducible after 2 and 6 months. The proximal urethra remained patent with no post-void residual urine after autonomic denervation. There was no significant urethral fibrosis after realignment of the transected urethra in the 2 sacrificed phases 2 and 3 dogs. CONCLUSIONS: From this study we concluded that autonomic denervation reduced pressure in the proximal urethra by less than 50%. Continuity of the urethra with the bladder is not necessary for proper urethral function. After autonomic denervation the proximal urethra remained patent with no subsequent fibrosis. In addition, no post-void residual urine was noted. Bilateral pudendal denervation did not completely block activity of the distal urethra. The nonneuromuscular components had a small role in the creation of urethral closure function.     

Urodynamic evaluation after endoscopic modified bladder neck suspension.

A total of 45 simplified double-needle bladder neck suspensions for genuine stress incontinence were clinically and urodynamically evaluated pre- and postoperatively. After a mean follow-up of 26 months, the subjective cure rate was 82.2% and the objective cure rate was 86.6%. Comparison of the pre- and postoperative urodynamic parameters showed a significant change in the maximum urethral closure pressure, functional urethral length, bladder capacity and maximum urine flow rate but no significant alteration in maximum detrusor pressure and first sensation during bladder filling. In summary, the modified bladder neck suspension effectively restores normal urethral function urodynamically.     

Mechanism of Postoperative Urinary Continence

Stress incontinence used to be attributed mostly to urethral hypermobility, and consequently most surgical techniques focused on the region of the bladder neck and proximal urethra. This article reviews our knowledge about the mechanism of postoperative urinary continence based on anatomic, imaging and urodynamic studies. Reduction of urethral mobility, as measured by cotton swab testing or imaging studies, is not the only reason why continence surgery succeeds. Imaging techniques are of limited value for elucidating the continence mechanism because radiologic landmarks and criteria are not reproducible. Urodynamically, the increased pressure transmission after successful continence surgery is attributed to the retropubic repositioning of the urethra, its compression against the anterior vaginal wall, and improved transmission of intra-abdominal pressure during stress. The role of the ‘functional’ urethral obstruction remains to be studied. In incontinent patients with hypermobility of the bladder neck and proximal urethra continence can be achieved by surgical correction. However, stress incontinence is possible in the absence of urethral hypermobility, and standard surgical techniques can fail to restore continence in these patients.     

Is there a urodynamic equivalence to anterior urethra in the male?

To evaluate the role of the anterior urethra in the male in micturition dynamics, 9 patients with urethral strictures who were undergoing a two-stage Turner-Warwick urethroplasty were evaluated with flow and pressure flow measurements, pre- and post-second-stage urethroplasty. Any decrease in flow or increase in resistance after closure would suggest an anterior “urethral effect.” None was found, indicating that the anterior urethra in the male functions as an inert conduit     

Variations in urethral and bladder pressure during stress episodes in healthy women

Pressure variations in the urethra and bladder during stress episodes and their time separations were investigated in 30 healthy female volunteers. The pressure was measured by means of a double microtip transducer catheter with the distal sensor in the bladder and the proximal sensor at the bladder neck, the mid-urethra and the distal urethra. In advance of the pressure spike during cough a pressure rise was demonstrated in the bladder and at all 3 sites of measurement in the urethra. The urethral pressure increments preceding and following the pressure spike were statistically significantly higher in the mid-urethra than the corresponding bladder pressures. This active urethral pressure generation in the mid-urethra and distal urethra was initiated 200 ms before the bladder pressure began to rise. The pressure in the urethral high pressure zone was higher than the bladder pressure in all cases. Passive pressure transmission to the urethral high pressure zone can take place only insignificantly due to a continuous higher pressure inside the urethra than in the bladder and due to the location of the high pressure zone in the demarcation of the abdominal cavity. It was concluded that the urethral pressure rise in the high pressure zone during stress episodes is mainly generated actively by intra- and/or peri-urethral structures.     

Clinical import of beta-adrenergic activity in the proximal urethra

Beta-adrenergic activity of the proximal urethra was studied in 11 patients. Maximum urethral pressure was recorded before, and 20 and 60 minutes after the intravenous administration of 0.5 mg. orciprenaline sulfate. There was a 40 per cent or more decrease in the maximum urethral pressure in 6 of the 11 patients. Beta-adrenoreceptor agonists could prove useful in facilitating vesical emptying by reducing urethral resistance in patients with neurogenic bladder dysfunction.     

An analysis of urethral viscoelasticity with particular reference to the sphincter function in healthy women

Urine ingression into the urethra involves stretching of the fibers, resulting in a pressure increase. This study describes the pressure response following a rapid urethral dilation. A probe for simultaneous recording of cross-sectional area (dilatation) and pressure was used. The urethral dilatations were induced by a gravitationally operated pump. Fifteen healthy women were studied. The pressure response (viscoelastic reaction) is a steep increase with the maximum at the end of dilatation. The maximum pressure is followed by a pressure decay (stress relaxation) over the next few seconds. The pressure response was highly dependent on the size and rate of dilatation but not on the urethral site of measurement. The median pressure response to a dilatation of 10 mm² at a rate of 150 mm²/s (chosen arbitrarily within the physiological range) is 45 cmH₂O. The pressure response may account for 25% of the urethral resistance to dilatation.