Predictive value of maximum urethral closure pressure, urethral hypermobility and urethral incompetence in the diagnosis of clinically significant female genuine stress incontinence

PURPOSE: We determined the value of urethral hypermobility, maximum urethral closure pressure (MUCP) and urethral incompetence in the diagnosis of stress urinary incontinence (SUI). MATERIALS AND METHODS: In this study 369 women with clinical symptoms suggestive of SUI without symptoms of bladder overactivity were evaluated in regard to urethral incompetence, urethral hypermobility and mean MUCP. The cohort was divided into 2 groups according to continence/incontinence status. ROC curves were used to test the performance of the various predicting factors. These factors were combined in forward stepwise logistic regression to find the cutoff point that simultaneously optimized sensitivity and specificity. RESULTS: Continent and incontinent patients differed with regards to urethral incompetence and hypermobility (each p <0.0001). Incontinent patients had a greater probability of a higher grade of each factor. Even after adjusting for the older age of incontinent patients by ANCOVA. MUCP was significantly lower in the incontinent group (p <0.001). The best univariate optimized cutoff point for discriminating continence from incontinence was obtained with urethral incompetence greater than grade I. CONCLUSIONS: The best single predictor of clinically significant SUI is urethral incompetence, followed by urethral hypermobility and MUCP. When combining several factors, namely grade II urethral incompetence with grade III hypermobility, grade III urethral incompetence with grades I to III hypermobility and grade IV urethral incompetence with or without urethral hypermobility, all indicated more than a 90% probability of clinically significant SUI.     

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.     

Timing of urethral pressure pulses before and after continence surgery

In continent women, urethral pressure with stress events has been found to rise approximately 200 msec before pressure in the bladder begins to rise. We studied the time difference in incontinent women, women after successful and unsuccessful incontinence procedures, and continent women, to evaluate the timing of urethral pressure rises in correlation with continence status. We analyzed the urodynamic data of 20 incontinent patients before and after successful or unsuccessful (n = 10 each) Raz needle suspension. Ten continent women served as controls. The time difference between onset of the pressure increase in the urethra and in the bladder was noted before and after surgery. In all 10 continent women the pressure increase in the urethra started to rise approximately 160 msec before the pressure increase in the bladder. In 16 of 20 incontinent patients the pressure in the urethra and bladder rose simultaneously. Successful antiincontinence procedures restored the early onset of urethral pressure increases. Unsuccessful operations did not produce this effect. Successful antiincontinence operations permit timely compression of the urethra. This timely compression is associated with continence. Neurourol. Urodynam. 17:19–23, 1998. © 1998 Wiley-Liss, Inc.     

Effect of narcotic anesthesia and skeletal muscle paralysis on passive and dynamic urethral function of stress continent and incontinent women

The aim of this study was to assess the importance of conscious skeletal muscle activity on the resting and stressed urethral sphincteric mechanism in stress continent and stress incontinent women. We evaluated the effects of loss of consciousness induced by a narcotic-based general anesthetic technique, with and without concurrent skeletal muscle paralysis, urethral sphincteric function. Nine premenopausal women who underwent vaginal hysterectomy without continence surgery had passive and dynamic urethral pressure profilometry performed within 24 hours before surgery, while asleep and totally paralyzed following endotracheal intubation before the start of surgery, while asleep and totally nonparalyzed at the end of surgery, and at the time of discharge from the hospital on the second or third postoperative day. Five subjects were stress incontinent and four had mild genuine stress incontinence but did not desire continence surgery with their hysterectomy. Measurements analyzed included urethral maximum closure pressure (MUCP) and functional length (FUL) from the passive profiles and bladder to urethra pressure transmission ratios (PTR) for each quarter of the urethra from the dynamic profiles. We found significant attenuation of urethral sphincteric function with stress due to muscle paralysis and loss of consciousness independent of muscle paralysis. Passive urethral function was more significantly depressed by paralysis than by loss of consciousness. These changes were statistically sifnificant only in stress continent subjects and not in the stress incontinent subjects, an observation that supports other evidence suggesting that there are important neuromuscular components in the pathogenesis of stress incontinence.     

Rotational differences in urethral pressure in incontinent women

Urethral pressure profile measurements are made by means of microtransducers at four different positions in the urethra (anterior, posterior, left and right side). The maximum urethral closure pressure (MUCP) is always highest in the anterior position in stress as well as in urge incontinent women. The functional urethral length shows no differences in the four positions. In all positions the recorded pressures and urethral length are higher in the urge incontinent group than in the stress incontinent group. A decrease of MUCP with age is observed in both groups.     

The risk of postoperative urinary incontinence after surgical treatment of genital prolapse

Full urodynamic assessment, including urethral profiles at rest and under stress, was made before and after surgery for severe urogenital prolapse in 40 continent women. Profilometry was also recorded after reduction of the prolapse by a vaginal pessary. The aim of this study was to try to determine criteria to prevent postoperative incontinence. After surgery, 6 patients (15%) became stress incontinent. The operation tends to diminish urethral obstruction (diminution of the residual volume) and negatively affects urodynamic urethral parameters (diminution of the residual continence area). The pessary test was not predictive of postoperative incontinence. Preoperative transmission ratio <100% and/or maximum urethral closure pressure <35 cmH₂O are proposed as predisposing factors for postoperative iatrogenic incontinence. Therapeutic implications are discussed.     

The urethral pressure profiles in continent and stress-incontinent women

Simultaneous urethrocystometry, including recording of the urethral pressure profile, was performed in 127 women aged 30 to 69 years; 42 of the women were free from urologic disorders and 85 had stress incontinence of urine. Both groups were subgrouped according to age. The results in the continent and the incontinent women were analyzed separately, in order to disclose any age-related changes. The data within each decade of age were also comparatively analyzed. In the bladder pressure at rest no age-related changes were found, and the readings were similar in the continent and the incontinent women. The maximum urethral pressure fell significantly with rising age in both groups and was significantly reduced in stress incontinence. The urethral closure pressure showed variations similar to those in the maximum urethral pressure. No lower limit of urethral closure pressure that definitely predisposed to stress incontinence could be established. The functional length of the urethra diminished significantly with rising age in the continent, but not in the incontinent women. The absolute length of the urethra did not show such diminution. Both the functional and the absolute urethral length were significantly less in the incontinent than in the continent women in the age groups between 30 and 49 years.     

Observations on the function of the female urethra: III: An overview with special reference to the relation between urethral hypermobility and urethral incompetence

AIMS: To analyze the relation between urethral hypermobility and urethral incompetence, and to summarize the interdependence between maximum urethral closure pressure (MUCP), urethral hypermobility, and urethral incompetence. PATIENTS AND METHODS: A group of 255 patients was selected from a large bank of cases. Inclusion criteria were age 20 years or above, no neurological disease, stable bladder, and no previous incontinence surgery or hysterectomy. The degree of hypermobility (cysto-urethrocele) and the degree of urethral incompetence (abdominal leak point pressure (ALPP)) were determined. Statistical analyses between urethral hypermobility and incompetence were performed with Spearman's correlation and the Jonckherre-Terpstra test. RESULTS: The Spearman's rank correlation test showed a statistically significant relation between urethral hypermobility and the degree of urethral incompetence (P = 0.0049). CONCLUSIONS: The statistically significant relation between urethral incompetence and hypermobility suggests that urethral incompetence will increase as the degree of urethral hypermobility does. Optimal conditions for urinary continence include a high maximum urethral closure pressure, absence of hypermobility, and a low degree of urethral incompetence. This last factor is assured by a strong support underneath the urethra permitting compression of the latter during straining. Failure of the urethral closure mechanism is highly probable with a diminished maximum closure pressure accompanied by urethral hypermobility often associated with a high degree of urethral incompetence. Clinically significant urinary incontinence may appear in many intermediate circumstances between these two extreme states, but stress urinary incontinence is essentially an activity-related phenomenon.     

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.     

Stress incontinence investigated with urodynamics 30 years ago

An article published in 1961 is reviewed. It reported on the simultaneously measured pressures in the urethra and bladder of both healthy women and women afflicted by stress incontinence. It was found that the difference between the two pressures was crucial for the preservation of continence. If pressure in one section of the urethra was higher than in the bladder, urine could not enter that section and closure was maintained. In patients with stress incontinence it was noted that when the difference in pressure, closure pressure, was lowered to zero during coughing, leakage would be noted. This was due to low urethral muscle tone causing a low resting closure pressure, as well as to an incomplete transmittance of abdominal pressure to the upper urethra. An operation for stress incontinence causes the upper urethra to be more fully exposed to increases in intra-abdominal pressure, so that physical activity has less effect on closure pressure.     

Significance of preoperatively observed detrusor overactivity as a predictor of continence status early after robot-assisted radical prostatectomy

Several recent studies have reported the involvement of bladder dysfunction in the delayed recovery of urinary continence following radical prostatectomy （RP）. The objective of this study was to investigate the significance of detrusor overactivity （DO） as a predictor of the early continence status following robot-assisted RP （RARP）. This study included 84 consecutive patients with prostate cancer undergoing RARP. Urodynamic studies, including filling cystometry, pressure flow study, electromyogram of the external urethral sphincter and urethral pressure profile, were performed in these patients before surgery. Urinary continence was defined as the use of either no or one pad per day as a precaution only. DO was preoperatively observed in 30 patients （35.7%）, and 55 （65.5%） and 34 （40.5%） were judged to be incontinent 1 and 3 months after RARP, respectively. At both 1 and 3 months after RARP, the incidences of incontinence in patients with DO were significantly higher than in those without DO. Of several demographic and urodynamic parameters, univariate analyses identified DO and maximal urethral closure pressure （MUCP） as significant predictors of the continence status at both 1 and 3 months after RARP. Furthermore, DO and MUCP appeared to be independently associated with the continence at both I and 3 months after RARP on multivariate analysis. These findings suggest that preoperatively observed DO could be a significant predictor of urinary incontinence early after RARP; therefore, it is recommended to perform urodynamic studies for patients who are scheduled to undergo RARP in order to comprehensively evaluate their preoperative vesicourethral functions.     

Effect of voluntary attention on urethral pressure

We have systematically and simultaneously recorded vesical pressure and maximum urethral closure pressure (MUCP) in 109 women consulting for urinary incontinence over an extended period of time. During the recording, we asked them to peform a mental calculation (MC) test and other tests designed to induce an effort of voluntary attention. We found a significant increase in MUCP during the MC. At rest, 57 women displayed urethral pressure variations (UPV) higher than 15 cm H₂O. MC inhibited UPV in 80% of these cases. Such variations have never yet been reported. The effect of MC can be compared to an orienting reaction, which normally increases the sympathetic tonus. The role of the smooth and striated muscle fibers of the urethra, in the observed changes in urethral pressure, is discussed in light of the literature data.     

Urethral resistance measurement: a new method for evaluation of stress urinary incontinence in women

The aim of this study was to evaluate a new method to measure urethral resistance among 66 women with urinary incontinence. A stainless steel sphere attached to a guide wire was developed. The sphere is inserted into the bladder and withdrawn through the urethra at a steady rate. Serial measurements with spheres of 5, 6 and 7 mm were performed. The mean urethral resistance as measured by the largest sphere (0.07±0.03) was significantly greater than that measured by the medium sphere (0.06±0.02, p<0.0001), which was significantly larger than that measured by the smallest sphere (0.04±0.01, p<0.0001). There was good correlation of urethral resistance with maximum urethral closure pressure (MUCP) by this technique, but no correlation with Valsalva leak point pressure (VLPP).Editorial Comment: This study attempts to demonstrate the validity and reproducibility of measuring maximum urethral resistance. Further studies will need to be performed to see if this technique will be clinically useful, i.e., comparing values in continent and incontinent women, old vs. young population, etc. There is a need to better test to measure urethral function than leak point pressure and urethral pressure profile/MUCP     

The effect of phenylpropanolamine on female stress urinary incontinence

In a randomized double-blind manner, 43 women with grade I and II stress urinary incontinence were treated with either phenylpropanolamine p.o. 50 mg twice daily (Rinexin, 1 tablet b.i.d.) or placebo during two weeks. Urethral CO2 profilometry, with recording of maximum urethral closure pressure (MUCP) and functional urethral length (FUL), and subjective response were considered for effect evaluation. The subjective response of Rinexin was highly significant (p = 0.01) above that of placebo. Clinical improvement was reported by 15 of 21 women on Rinexin and by 8 of 22 women on placebo. A significant increase in MUCP, 14%, was registered in women on Rinexin treatment. This increase was more pronounced in the grade I than in the grade II incontinent women. No statistically significant correlations were obtained between subjective response and increase in MUCP. An increase in FUL was recorded in both two treatment groups, but no statistically significant difference between them was obtained. Adverse drug reactions were rare. No changes in blood pressure occurred. Based on the present study, Rinexin (1 tablet b.i.d.) is an effective and safe medication for female grade I and II stress incontinence and is also recommended as adjunctive therapy to physiotherapy before Teflon injection or operation.     

Urethral closure pressure with stress — A comparison between stress-incontinent and continent women

Summary Stress incontinence has been said to occur as a consequence of a low urethral pressure and defective pressure transmission from the abdomen to the urethra due to descent of the bladder neck area. Equipment suitable for dynamic pressure measurements has been used to analyse the losses of urethral pressure that lead to incontinence. The pressure transmission from abdomen to urethra was found to be incomplete in both continent and stress-incontinent women. There was also significant loss of smooth muscle tone in the urethral wall after repeated straining, leading to a still narrower margin between the urethral pressure and the leakage treshold in both continent and stress-incontinent women. The main factor determining the degree of continence or incontinence seemed to be the urethral closure pressure at rest. As long as this pressure is sufficiently high, leakage during sudden stress will not occur.     

A Comparison of Urethral Profilometry using Microtip and Fiberoptic Catheters

This paper compares urethral profilometry measurements using two different types of catheter: the Millar microtip transducer and the FST fiberoptic catheter. Outcome variables were functional urethral length (FUL), maximum urethral closure pressure (MUCP), and mean pressure/transmission ratio (PTR). Thirty women presenting to the urodynamics laboratory with symptoms of stress urinary incontinence were evaluated with both catheters. All subjects underwent two passive urethral pressure profiles and two dynamic (cough) urethral pressure profiles with each catheter. For FUL and MUCP, the means of the two passive measurements were compared between catheters. For PTR, the means of the two dynamic measurements were compared between catheters. There was no difference in FUL between the two catheter types. The FST measurements of MUCP and PTR were lower than the microtip measurements. Twenty per cent of patients would have been diagnosed with low-pressure urethra with the FST catheter, but not with the microtip catheter. Caution must be used when applying urethral measurements taken with the fiberoptic catheters to standards set with microtip catheters.     

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.     

Observations on the function of the female urethra: II: Relation between maximum urethral closure pressure at rest and the degree of urethral incompetence

AIMS: To study the relation between maximum urethral closure pressure (MUCP) at rest and the degree of urethral incompetence in the female. PATIENTS AND METHODS: Two hundred fifty five patients aged 20 years or older, with stable bladders on multichannel urodynamics, without known neurological pathology, and with no previous history of pelvic or anti-incontinence surgery were included in the study. Resting urethral pressure profile (UPP) and the grade of urethral incompetence was registered. RESULTS: Mean age of the group was 45.6+/-12.7 years; mean MUCP was 62.7+/-28.5 cm of water. There was a statistically significant difference in the MUCP when the different grades of urethral incompetence were compared to each other, the higher grades being associated with a lower maximal closure pressure. CONCLUSIONS: This study demonstrates that there is a highly significant relationship between MUCP and between all grades of urethral incompetence. This supports previous observations that MUCP decreases when abdominal leak point pressure (ALPP) is low and that this might be secondary to some mechanical failure in the pressure transmission from the abdominal cavity to the urethra. Studies should never compare continent to incontinent cohorts without considering their ALPP because in doing so they are comparing groups that are functionally heterogeneous.     

Continuous recording of urethral activity in healthy female volunteers

The pressure variations at the maximal urethral closure pressure (MUCP) were continuously recorded in healthy female volunteers by means of a two-point microtip transducer catheter for one hour. Before the investigation a normal voiding was assured objectively and bladder instability was excluded. All women showed pressure variations both at the MUCP and more distally. The pressure variations, from 3 to 66 cm H₂O, showed rhythmicity and three frequency ranges could be identified. Slow pressure waves with a frequency of one in eight to 19 minutes were observed. Relatively fast-pressure waves were observed (one every one to four minutes) and relatively fast-frequency pressure waves were observed (rate: one to eight per minute). The pressure variations of the urethra seem to be an aspect of normal urethral physiology possibly contributing to continence and urinary tract infection prevention.     

Urethral closure pressures among primiparous women with and without levator ani muscle defects

Introduction and hypothesis

Vaginal birth is an established risk factor for levator ani (LA) defects and incontinence. We hypothesized an association between urethral pressure profiles and LA defects.

Methods

One hundred sixty primiparous women, 9?C12?months postpartum, were assessed with MRI for LA defects, urodynamic testing, and instrumented speculum for vaginal closure force. Urodynamic testing included resting maximal urethral closure pressure (MUCP) and urethral closure pressure with a pelvic floor contraction or Kegel (KUCP). We examined the relationships between MUCP, KUCP, LA defect status, and vaginal closure force.

Results

There was no significant association between MUCP or KUCP in women with and without LA defects (p?=?0.94, p?=?0.95). Additionally, there was no correlation between MUCP and vaginal closure force (r?=?0.06, p?=?0.41), and a weak correlation between KUCP and vaginal closure force (r?=?0.20, p?=?0.01).

Conclusions

In this population, urethral pressure profiles are unrelated to LA defect status after vaginal birth, indicating that the mechanism responsible for LA damage spares the urethra.