Observations on the function of the female urethra: I: relation between maximum urethral closure pressure at rest and urethral hypermobility

AIMS: To study the relation between maximum urethral closure pressure at rest and urethral hypermobility in female patients. PATIENTS AND METHODS: We selected 255 patients aged 20 years and older, with a stable bladder on multichannel urodynamics, without known neurological pathology, and without a history of pelvic or anti-incontinence surgery. A resting urethral pressure profile and the degree of urethral hypermobility were registered. Two-tailed analyses of variance (ANOVA) with Fisher's post-hoc tests were used to detect any statistically significant difference (P < 0.05) in urethral closure pressure between groups with varying degrees of urethral hypermobility. RESULTS: Mean age was 45.6 +/- 12.7 (range 20-77) years. Mean maximum urethral closure pressure for the entire group was 62.7 +/- 29 (range 10-150) cm of water. A statistically significant inverse relationship was found between age and maximum urethral closure pressure (r = 0.489, P < 0.0001) when both analyzed as continuous variables, and with age categorized in 10-year increments (P < 0.0001). When comparing mean urethral closure pressure in each group examined for urethral hypermobility, a statistically significant difference was noted when grades I, II, and III were compared to grade 0 hypermobility. No significant difference was observed when grades I, II, and III were compared to each other. Even if statistically non-significant, there exists an inverse relationship between the degree of urethral hypermobility and the maximum urethral closure pressure: a higher hypermobility is associated with a lesser urethral closure pressure. CONCLUSIONS: Urethral closure pressure falls significantly when urethral hypermobility is present. This decrease is not related to patient's age or parity. Our observations demonstrate an inverse relation between urethral closure pressure and the degree of cysto-urethrocele. As hypermobility increases, closure pressure decreases, even if this decrease does not reach the level of statistical significance.     

前尿道内支架管在治疗前尿道狭窄中的应用

目的:观察在前尿道狭窄患者中留置前尿道支架管的临床疗效。方法:选取2005年1月至2008年5月在本院住院治疗及进行门诊尿道扩张的患者共38例作为治疗组,并将同期在本院采取尿道扩张器扩张的患者38例纳入对照组,通过最大尿流率(Qmax)及扩张次数等指标对两组的临床疗效进行对比分析。结果:尿流率检测表明留置支架管后所有患者的Qmax均较术前明显增加,对拔管后6个月随访结果进行分析,治疗组Qmax>15ml/s的患者显著多于对照组(P<0.05)。结论:采用前尿道内留置支架管治疗前尿道狭窄不但显著减少扩张次数,减轻患者的经济负担,也显著改善患者的生活质量,前尿道狭窄患者中留置前尿道内支架管不失为临床上一种较好的治疗手段,并取得了良好的预期效果,简单易行,效果确切,值得推广。     

Decrease in urethral pressure following repeated cough efforts: A new concept for pathophysiology of stress urinary incontinence

AIMS: To describe the decrease in maximum urethral closure pressure (MUCP) following repeated coughs in women with stress urinary incontinence (SUI). METHODS: MUCP was recorded at rest and after seven cough efforts in 70 women under age 40 referred for urodynamic investigation (47 women with SUI and 23 women without SUI). RESULTS: The intraclass correlation coefficient for repeatability was very good at 400 mL filling volume: 0.94 (95%CI: 0.85-0.98), as compared to the mean and standard-deviations of the MUCP measurements. A decrease in MUCP >20% after seven cough efforts was observed in 18(38%) patients in the SUI group and in just 1(4%) woman in the non-SUI group (P = 0.0069). CONCLUSIONS: Many women with SUI exhibit a sharp decrease in MUCP after repeated coughs. Many hypotheses may explain this phenomenon, including increased fatigue of the periurethral muscles.     

Comparison of the urethral properties of the female guinea pig and rat

AIMS: The main focus of this study was to profile and compare urethral function in the female guinea pig and rat, and to characterize urodynamically distinctive patterns in the micturition cycle of the two species. This exercise aimed to investigate potential species-related differences and determine a suitable animal model for the human urethra. MATERIALS & METHODS: Female Dunkin-Hartley guinea pigs (400-500 g) and Sprague-Dawley rats (200-300 g) were used throughout the study. For in vitro experiments urethral rings were suspended vertically for isometric tension recording in 5 ml organ baths and drugs (phenylephrine 10(-4) M and carbachol 10(-4) M) were applied directly to the bathing solution. In vivo urethral pull-through and urodynamic studies were performed under urethane anesthesia, and phenylephrine (200 microg/kg) was administered during urethral pull-through experiments via the intravenous (i.v.) route. Urethral, bladder and arterial pressures, and external urethral sphincter electromyographic (EMG) spike activity were recorded simultaneously throughout. RESULTS: Organ bath studies coupled with in vivo pull-through experiments produced urethral profiles with distinct regional variations for both species. Urodynamic studies with the urethral probe fixed in the high pressure zones of the proximal urethra produced similar recordings in both species during bladder filling and marked differences during micturition. The guinea pig showed complete sphincteric inhibition immediately prior and during micturition as also seen in the human, whereas the rat exhibited high frequency bursts in EMG activity at this stage in the cycle. CONCLUSIONS: The EMG activity seen in the rat during micturition is presumably necessary for efficient voiding, thus the guinea pig is a more suitable comparative model for the human in relation to urethral properties during micturition.     

A Case of Primary Localized Amyloidosis of the Penile Urethra

Primary localized amyloidosis of the penile urethra is rare. We report a case in which the urethra was obstructed by amyloid tissue without evidence of systemic amyloidosis. After urethral dilatation, the patient reported a markedly improved urinary stream with minimal dysuria.     

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.     

Urethral retro-resistance pressure: a new clinical measure of urethral function

AIMS: The urethral retro-resistance pressure (URP) is a new retrograde measurement of urethral function. URP is the pressure required to achieve and maintain an open sphincter. The assessment of any potential diagnostic measure must include an evaluation in individuals both with and without disease. In this study, we examined URP values in women without urinary incontinence. METHODS: Four centers enrolled 61 women who did not report symptoms of urinary incontinence, and who had negative standing stress tests (SST). Each center was to perform three consecutive URP measurements on each subject. At two centers, 32 subjects returned in 3-7 days for three additional URP measurements. We compared the average URP in this asymptomatic population to the average URP from women symptomatic of stress urinary incontinence (SUI) derived from a previous study. We evaluated the within-subject variation of the URP measurement at a single visit and the within-subject change in URP over time using test and retest values. RESULTS: The mean age was 33 +/- 9 years and the mean body mass index (BMI) was 24 +/- 6. URP values were normally distributed. The mean URP at visit 1 was 112.6 +/- 39.2 cm H2O (n = 60). This was statistically significantly different from the mean URP of symptomatic women (69.9 cm H2O, P < 0.0001). The within-subject standard deviation of URP at visit 1 was 12.6 +/- 12.6 cm H2O (n = 60) and at retest visit was 9.3 +/- 6.2 cm H2O (n = 32). For the retest cases, the mean URP at visit 1 was 113.9 +/- 39.9 cm H2O (n = 32) and at retest visit was 125.5 +/- 33.9 cm H2O (n = 32) (Wilcoxon Signed Rank test, P = 0.145). CONCLUSIONS: The mean URP measurement obtained in this study of asymptomatic women showed significantly higher values when compared to our study in women with SUI. The URP measurements were consistent within the same subject. Furthermore, there was no statistically significant difference in the URP measurement from visit 1 to retest visit. The data suggest that URP shows promise as a physiological urethral pressure measurement.     

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.     

Prospective evaluation of the American Urological Association symptom index and peak urinary flow rate for the followup of men with known urethral stricture disease

PURPOSE: We prospectively evaluated the American Urological Association (AUA) symptom index and maximum urine flow for predicting urethral stricture recurrence in men with a previous diagnosis of urethral stricture disease. MATERIALS AND METHODS: Patients were recruited at our urethral stricture clinic, where all newly diagnosed and previously treated men with urethral stricture present and are treated. The AUA symptom index was completed and uroflowmetry was done. The stricture was calibrated using Jacques catheters. If an 18Fr catheter could not be passed, a retrograde urethrogram was performed. Patients were treated with filiform dilation or direct vision internal urethrotomy. Uroflowmetry was repeated when the catheter was removed 3 days later and the AUA symptom index was repeated 1 month later. RESULTS: Data on 49 patients (170 consultations) between March 2000 and August 2001 were analyzed. Average patient age was 48 years. There was a significant negative correlation of urethral diameter with AUA symptom index and of AUA symptom index with maximum urine flow as well as a significant positive correlation of urethral diameter with maximum urine flow. We evaluated the usefulness of AUA symptom index and maximum urine flow at different cutoff levels for predicting urethral stricture in our study group. Using an AUA symptom index of greater than 10 or maximum urine flow of less than 15 ml. per second as cutoff values provided 93% sensitivity, 68% specificity, 78% positive predictive value, 89% negative predictive value and 82% overall accuracy. This method could have prevented further invasive studies in 34% of patients, while a clinically significant stricture would have been missed in only 4.3%. CONCLUSIONS: AUA symptom index combined with maximum urine flow is an accurate, time-saving and cost-effective tool for predicting recurrent stricture in patients with a known urethral stricture. It can be used to direct decision making on further invasive studies and treatment.     

Expansion and fixation properties of a new braided biodegradable urethral stent: an experimental study in the rabbit

PURPOSE: Biodegradable spiral urethral stents have been used with favorable results combined with thermal treatments of the prostate and for recurrent urethral strictures but the configuration of the helical spiral is not ideal. We developed a new tubular mesh configuration for the biodegradable urethral stent and evaluated its expansion and locking properties in the rabbit urethra. MATERIALS AND METHODS: The stents were made of self-reinforced polylactic acid polymer (Bionx Implants, Ltd., Tampere, Finland) blended with BaSO (Alfa Chem, New York, New York) to achieve radiopacity. Two braiding patterns, that is 1 over 1 and 2 over 2 + 1, were used to produce a tubular mesh structure. Stainless steel stents (pattern 1 over 1) served as controls. The stents were inserted into the posterior urethra of 27 male rabbits. The animals were sacrificed after 1 week, 1 and 6 months, respectively. X-rays were done immediately after stent insertion and at sacrifice. Longitudinal movement and expansion were assessed on the x-rays.(4) RESULTS: All stents maintained position in the urethra without fixation. Macroscopic disorientation of the structure of the 2 over 2 + 1 braided self-reinforced polylactic acid polymer stents began before 1 month, while 1 over 1 braided stents retained their construction. At 6 months 3 of 6 biodegradable stents were degraded. Average longitudinal movement was 2 mm. (range 1 to 3) in the 1 over 1 self-reinforced polylactic acid polymer group, 2 mm. (range 0 to 7) in the 2 over 2 + 1 polylactic acid group and 3 mm. (range 3 to 3) in controls at 1 month. CONCLUSIONS: Biodegradable polymers are suitable materials for braided urethral stents. The expansion properties of the 2 braiding models tested in this study sufficed to fix the stents in situ in the prostatic urethra. However, the 1 over 1 braiding pattern was superior to the 2 over 2 + 1 pattern, in that it retained its macroscopic construction until the degradation of single self-reinforced polylactic acid polymer fibers.     

Supraspinal N-methyl-D-aspartate receptor inhibition influences the micturition reflex and function of the upper urinary tract of anesthetized and conscious rats

AIMS: To examine the effects of N-methyl-D-aspartate (NMDA) receptor antagonists on the frequency/volume (F/V) characteristics of micturition of conscious and anesthetized rats in relation to the mechanisms of renal urine output and pyelo-ureteral transport function of the upper urinary tract. METHODS: Micturition F/V characteristics of 24 conscious female Sprague-Dawley rats, each weighting 160-180 g, were evaluated in a metabolic chamber. Control values of (F/V) were first obtained after administration of a 5-mL loading dose of saline solution and compared with intraperitoneal (i.p.) injection of 0.3-6.0 mg/kg of LY274614 (LY) and 0.3-40 mg/kg of dextromethorphan (DEX). Upper urinary tract studies were performed on two groups of urethane anesthetized rats (1.2 g/kg, s.c.). A group of 17 rats was used for intravenous (i.v.) injection of 1-30 mg/kg of LY and 1-10 mg/kg of DEX. In a second group of 12 rats, 0.2 mg/kg of LY and DEX were administered intracerebroventricularly (i.c.v.), by placing a catheter into the third ventricle. In anesthetized rats, continuous cystometrograms (CMG) were done while perfusing the renal pelvis with indigo carmine, and measuring pelvic and arterial pressure and as well as visualizing the transport of urine within the upper urinary tract by using videomicroscopic imaging. RESULTS: In conscious rats, the i.p. injection of LY and DEX produced a significant and dose-dependent increase in functional bladder capacity and a considerable increase in diuresis. In anesthetized rats, i.v. and i.c.v. administration of LY and DEX affected the micturition reflex, reflected as a significant increase in bladder capacity and preleakage pressure. Videomicroscopic imaging shows dilation of the ureter and a dilution of the dyed urine after the i.v. and i.c.v. injection of LY and DEX. The frequency of ureteral peristalsis and renal pelvic contractions were significantly decreased after i.v. and i.c.v. injection of LY as well as DEX. CONCLUSIONS: The present study shows that the NMDA receptor antagonists LY and DEX given systemically (i.v. and i.p.) or intracerebroventricularly influence the micturition reflex and modulate pyelo-ureteral motility as well as the rate of urine production. From the present study, it is suggested that NMDA receptors are directly involved in regulating pyelo-ureteral peristalsis as well as in the coordination of urine transport between upper and lower urinary tract.     

Biodegradable urethral stents seeded with autologous urethral epithelial cells in the treatment of post‐traumatic urethral stricture: a feasibility study in a rabbit model

OBJECTIVE

To evaluate the adhesion and growth of rabbit urethral epithelial cells (UECs) on a biodegradable unbraided mesh urethral stent, and to assess the feasibility and effect of the cell‐seeded urethral stent for treating post‐traumatic urethral stricture (PTUS) in a rabbit model.

MATERIALS AND METHODS

Rabbit UECs were collected by biopsy from adult rabbit urethra and seeded onto the outer layer of a mesh biodegradable urethral stent. The growth of UECs in cell‐scaffolds was assessed by scanning electron microscopy, immunohistochemical and fluorescence staining. In all, 32 male New Zealand rabbits were used, with either PTUS or uninjured, as a control group. Cell‐seeded stents were implanted into the rabbits strictured urethra. The histological and immunohistochemical findings were assessed after death at 1, 2, 8, 12 and 24 weeks, respectively. The reconstruction and function were evaluated by urethroscopy and retrograde urethrography.

RESULTS

The cultured UECs adhered to the stent and grew well. Immunohistochemistry showed that the cells were stained positively for cytokeratin. At 4 weeks, vs 2 weeks, the thickness of the papillary projections of the epithelium decreased and inflammatory cell infiltration diminished. At 24 weeks the injured urethra was completely covered by integrated regeneration of three to five layers of urothelium. There was no evidence of voiding difficulty, stricture recurrence or other complications.

CONCLUSIONS

The unbraided mesh biodegradable urethral stent with autologous UECs seemed to be feasible for treating PTUS in the rabbit urethra, and provides a hopeful avenue for clinical application allowing reconstruction of PTUS.     

Restoration of external urethral sphincter function after pudendal nerve end-to-end anastomosis in the male rabbit

PURPOSE: In this study we rehabilitated external urethral sphincter function by pudendal nerve end-to-end anastomosis after experimental pudendal nerve axotomy in male rabbits. MATERIALS AND METHODS: A total of 17 animals were included in this study, including group 1-a control group of 5 (29.4%), group 2-6 (35.3%) and group 3-6 (35.3%). Animals from group 2 underwent bilateral axotomy and group 3 underwent pudendal nerve end-to-end anastomosis. In all groups we performed urodynamic investigations prior to axotomy, after axotomy or anastomosis, and 14, 42 and 90 days after axotomy or nerve anastomosis. RESULTS: In untreated group 1 control sphincter pressure was 28.5 cm H2O. In group 2 average urethral sphincter pressure was 5.6 cm H2O 14 days after axotomy with only a slight increase to 11.05 cm H2O by day 90. In group 3 external urethral pressure increased to 8.26 cm H2O after 14 days and to 21.32 cm H2O by postoperative day 90. CONCLUSIONS: External urethral sphincter deficiency after bilateral pudendal nerve axotomy demonstrates the primacy of the pudendal nerve in the innervation of the external urethral sphincter. We were able to rehabilitate external urethral sphincter function by performing pudendal nerve end-to-end anastomosis.     

Adult anterior urethral strictures: a national practice patterns survey of board certified urologists in the United States

PURPOSE: We determined the methods and patterns of the evaluation of and treatment for adult anterior urethral stricture disease by practicing urologists in the United States. MATERIALS AND METHODS: A nationwide survey of practicing members of the American Urological Association was performed by a mailed questionnaire. A total of 1,262 urologists were randomly selected from all 50 states, of whom 431 (34%) completed the questionnaire. RESULTS: Most urologists (63%) treat 6 to 20 urethral strictures yearly. The most common procedures used by those surveyed for urethral strictures were dilation (92.8%), optical internal urethrotomy (85.6%) and endourethral stent (23.4%). Minimally invasive procedures are used more frequently that any open urethroplasty technique. Furthermore, most urologists (57.8%) do not perform urethroplasty surgery. When used, the most common urethroplasty surgeries performed were end-to-end anastomotic urethroplasty, perineal urethrostomy and ventral skin graft urethroplasty. Few urologists (4.2%) performed buccal mucosa grafts. For a long bulbar urethral stricture or short bulbar urethral stricture refractory to internal urethrotomy 20% to 29% of respondents would refer to another urologist, while 31% to 33% would continue to manage the stricture by minimally invasive means despite predictable failure. Of the urologists 74% believed that the literature supports a reconstructive surgical ladder, in which urethroplasty is only performed after repeat failure of endoscopic methods. CONCLUSIONS: Most urologists in the United States have little experience with urethroplasty surgery. Most urologists erroneously believe that the literature supports a reconstructive surgical ladder for urethral stricture management. Unfamiliarity with the literature and inexperience with urethroplasty surgery have made the use of endoscopic methods inappropriately common.     

Motor evoked potentials from the striated urethral sphincter and puborectal muscle: normative values

AIMS: Transcranial magnetic stimulation enables the study of corticospinal motor pathways through evoked potential testing. By separate stimulation of cortical centers and spinal roots, it is possible to test motor conduction times segmentally. This method enables the localization of central or peripheral demyelinating neuropathies. As lower urinary tract dysfunction often accompanies these diseases, we wanted to present normative data for the motor innervation of the external urethral sphincter (EUS) and the puborectal muscle (PR). METHODS: Thirty healthy women without evidence of neurologic or lower urinary diseases were studied. They had a mean age of 52 years. Transcutaneous magnetic stimulations were applied to the vertex, the upper lumbar spine, and the sacrum. Evoked potentials were recorded with concentric needle electrodes placed in the EUS and the PR by a transvaginal route. Stimulations were performed with relaxed pelvic floor and with tonic contraction (facilitated responses). At least three responses were recorded for each modality. Stepwise multiple regression analysis was performed to test for the effect of age, height, body mass index, vaginal parity, and menopause. RESULTS: In some subjects, it was only possible to record cortical latencies with facilitation. Technical difficulties were encountered with spinal stimulations. Reference values are presented as means with 95% confidence intervals. Regression analysis revealed height as a dependent factor for sacral latencies. CONCLUSIONS: Our data can serve as reference values for future studies of the fast conducting fibers in patients with sphincter dysfunction. The height of the patient should be taken into account. The clinical applicability of the method is questionable.