Age changes in the human female urethra: a morphometric study

Urethral tissue characterization using multiparametric ultrasound imaging

A decrease in urethral closure pressure is one of the primary causes of stress urinary incontinence in women. Atrophy of the urethral muscles is a primary factor in the 15 % age-related decline in urethral closure pressure per decade. Incontinence not only affects the well-being of women but is also a leading cause of nursing home admission. The objective of this research was to develop a noninvasive test to assess urethral tissue microenvironmental changes using multiparametric ultrasound (mpUS) imaging technique. Transperineal B-scan ultrasound (US) data were captured using clinical scanners equipped with curvilinear or linear transducers. Imaging was performed on volunteers from our institution medical center (n = 15, 22 to 76 y.o.) during Valsalva maneuvers. After expert delineation of the region of interest in each frame, the central axis of the urethra was automatically defined to determine the angle between the urethra and the US beam for further analysis. By integrating angle-dependent backscatter with radiomic texture feature analysis, a mpUS technique was developed to identify biomarkers that reflect subtle microstructural changes expected within the urethral tissue. The process was repeated when the urethra and US beam were at a fixed angle. Texture selection was conducted for both angle-dependent and angle-independent results to remove redundancies. Ultimately, a distinct biomarker was derived using a random forest regression model to compute the urethra score based on features selected from both processes. Angle-dependent backscatter analysis shows that the calculated slope of US mean image intensity decreased by 0.89 (±0.31) % annually, consistent with the expected atrophic disorganization of urethral tissue structure and the associated reduction in urethral closure pressure with age. Additionally, textural analysis performed at a specific angle (i.e., 40 degrees) revealed changes in gray level nonuniformity, skewness, and correlation by 0.08 (±0.04) %, -2.16 (±1.14) %, and -0.32 (±0.35) % per year, respectively. The urethra score was ultimately determined by combining data selected from both angle-dependent and angle-independent analysis strategies using a random forest regression model with age, yielding an R2 value of 0.96 and a p-value less than 0.001. The proposed mpUS tissue characterization technique not only holds promise for guiding future urethral tissue characterization studies without the need for tissue biopsies or invasive functional testing but also aims to minimize observer-induced variability. By leveraging mpUS imaging strategies that account for angle dependence, it provides more accurate assessments. Notably, the urethra score, calculated from US images that reflect tissue microstructural changes, serves as a potential biomarker providing clinicians with deeper insight into urethral tissue function and may aid in diagnosing and managing related conditions while helping to determine the causes of incontinence.

What do we really know about the external urethral sphincter?

The external urethral sphincter (EUS), composed of skeletal muscle, along with a smooth muscle-lined internal urethral sphincter (IUS), have crucial roles in maintaining continence during bladder filling and facilitating urine flow during voiding. Disruption of this complex activity has profound consequences on normal lower urinary tract function during the micturition cycle. However, relatively little is known about the normal and pathological functions of these particular muscle types, how activity can be manipulated and regulated and why, for example, loss of EUS function and sarcopenia is associated with ageing. Here we discuss the unique physiological, biochemical and metabolic properties of striated and smooth muscle components of the urethral sphincter, which have distinct roles in maintaining continence during bladder filling. Relevant in vivo models for investigation of pathophysiological mechanisms, and for pre-clinical evaluation of therapeutic approaches are reviewed. Electromyography and Urethral Pressure Profile recordings are pivotal to understanding the function and dysfunction of the EUS and for clinical evaluation of e.g. urinary retention. Pre-clinical and clinical studies have revealed that age- or disease-related tissue remodelling that lead to filling/voiding disorders may be mitigated with emerging therapeutic approaches.

Nitrergic inhibition of sympathetic arteriolar constrictions in the female rodent urethra

During the urine storage phase, tonically contracting urethral musculature would have a higher energy consumption than bladder muscle that develops phasic contractions. However, ischaemic dysfunction is less prevalent in the urethra than in the bladder, suggesting that urethral vasculature has intrinsic properties ensuring an adequate blood supply. Diameter changes in rat or mouse urethral arterioles were measured using a video-tracking system. Intercellular Ca2+ dynamics in arteriolar smooth muscle (SMCs) and endothelial cells were visualised using NG2- and parvalbumin-GCaMP6 mice, respectively. Fluorescence immunohistochemistry was used to visualise the perivascular innervation. In rat urethral arterioles, sympathetic vasoconstrictions were predominantly suppressed by α,β-methylene ATP (10 μM) but not prazosin (1 μM). Tadalafil (100 nM), a PDE5 inhibitor, diminished the vasoconstrictions in a manner reversed by N-ω-propyl-l-arginine hydrochloride (l-NPA, 1 μM), a neuronal NO synthesis (nNOS) inhibitor. Vesicular acetylcholine transporter immunoreactive perivascular nerve fibres co-expressing nNOS were intertwined with tyrosine hydroxylase immunoreactive sympathetic nerve fibres. In phenylephrine (1 μM) pre-constricted rat or mouse urethral arterioles, nerve-evoked vasodilatations or transient SMC Ca2+ reductions were largely diminished by l-nitroarginine (l-NA, 10 μM), a broad-spectrum NOS inhibitor, but not by l-NPA. The CGRP receptor antagonist BIBN-4096 (1 μM) shortened the vasodilatory responses, while atropine (1 μM) abolished the l-NA-resistant transient vasodilatory responses. Nerve-evoked endothelial Ca2+ transients were abolished by atropine plus guanethidine (10 μM), indicating its neurotransmitter origin and absence of non-adrenergic non-cholinergic endothelial NO release. In urethral arterioles, NO released from parasympathetic nerves counteracts sympathetic vasoconstrictions pre- and post-synaptically to restrict arteriolar contractility. KEY POINTS: Despite a higher energy consumption of the urethral musculature than the bladder detrusor muscle, ischaemic dysfunction of the urethra is less prevalent than that of the bladder. In the urethral arterioles, sympathetic vasoconstrictions are predominately mediated by ATP, not noradrenaline. NO released from parasympathetic nerves counteracts sympathetic vasoconstrictions by its pre-synaptic inhibition of sympathetic transmission as well as post-synaptic arteriolar smooth muscle relaxation. Acetylcholine released from parasympathetic nerves contributes to endothelium-dependent, transient vasodilatations, while CGRP released from sensory nerves prolongs NO-mediated vasodilatations. PDE5 inhibitors could be beneficial to maintain and/or improve urethral blood supply and in turn the volume and contractility of urethral musculature.

The female urethra: urethral function throughout a woman's lifetime

INTRODUCTION AND HYPOTHESIS

The objective of this narrative review is to describe changes in urethral function that occur during a woman's lifetime. Evaluation of urethral function includes measurements of urethral closure pressure, at rest and during stress, leak point pressure, and the detailed study of anatomical and histological changes of the urethral sphincteric mechanism.

METHODS

A literature search in MEDLINE, PubMed, and relevant journals from 1960 until 2020 was performed for articles dealing with urethral function and the impact of aging, pregnancy, and childbirth, female hormones, and menopausal transition on the urethral sphincteric mechanism. Longitudinal and cross-sectional epidemiological surveys, studies on histological changes in urethral anatomy during aging, and urodynamic data obtained at different points in a woman's lifetime, during pregnancy, after childbirth, as well as the effects of female hormones on urethral sphincter function are reviewed. Relevant studies presenting objective data are analyzed and briefly summarized.

RESULTS AND CONCLUSIONS

The findings lead one to conclude that a constitutional or genetic predisposition, aging, and senescence are the most prominent etiological factors in the development of urinary incontinence and other pelvic floor disorders. Vaginal childbirth dilates and may damage the compressed pelvic supportive tissues and is invariably associated with a decline in urethral sphincter function. Pregnancy, hormonal alterations, menopausal transition, weight gain, and obesity are at best of secondary influence on the pathology of lower urinary tract dysfunction. The decline of circulating estrogens during menopausal transition may play a role in the transition of fibroblasts to cellular senescence.

Urinary flow through urethras with a rough lumen

AIMS

This study investigates how lumen roughness and urethral length influence urinary flow speed.

METHODS

We used micro-computed tomography scans to measure the lumen roughness and dimensions for rabbits, cats, and pigs. We designed and fabricated three-dimensional-printed urethra mimics of varying roughness and length to perform flow experiments. We also developed a corresponding mathematical model to rationalize the observed flow speed.

RESULTS

We update the previously reported relationship between body mass and urethra length and diameter, now including 41 measurements for urethra length and 10 measurements for diameter. We report the relationship between lumen diameter and roughness as a function of position down the urethra for rabbits, cats, and pigs. The time course of urinary speed from our mimics is reported, as well as the average speed as a function of urethra length.

CONCLUSIONS

Based on the behavior of our mimics, we conclude that the lumen roughness in mammals reduces flow speed by up to 25% compared to smooth urethras. Urine flows fastest when the urethra length exceeds 25 times its diameter. Longer urethras do not drain faster due to viscous effects counteracting the additional gravitational head. However, flows with our urethra mimics are still 6 times faster than those observed in nature, suggesting that further work is needed to understand flow resistance in the urethra.

Analysis of urethral blood flow by high-resolution laser speckle contrast imaging in a rat model of vaginal distension

OBJECTIVE

To investigate the feasibility of laser speckle contrast imaging (LSCI) for monitoring urethral blood flow (UBF).

MATERIALS AND METHODS

In this study, 18 healthy, virgin female Sprague-Dawley rats aged 8-week-old were used. The animals were divided into the sham group (n = 9) and the vaginal distension (VD) group (n = 9). The sham group underwent one catheterization of the vagina without distension and the VD group underwent one VD. Following the VD or sham treatment for one week, LSCI assessment of urethral blood flow was performed during bladder filling and leak point pressure (LPP) process.

RESULTS

During the LPP process, in the VD group, the mean LPP was significantly lower than in the sham group (p < 0.05) and the mean UBF level was also significantly lower than in the sham group (p < 0.05) in the LPP condition. The mean relative change of UBF (Δ Flow) was significantly different between the sham group and VD group. The value was 0.646 ± 0.229 and 0.295 ± 0.19, respectively (p < 0.05). During the bladder filling process, the VD group had a significant lower mean UBF level than the sham group under full bladder conditions (p = 0.008). The mean ΔFlow was also significantly lower than in the sham group. The value was 0.115 ± 0.121 and 0.375 ± 0.127, respectively (p = 0.016).

CONCLUSIONS

The results confirmed that LSCI was able to determine UBF in female rats. The VD group had lower baseline UBF and lower increases in UBF during bladder filling and LPP process compared with the sham group.

Urethral function and failure: A review of current knowledge of urethral closure mechanisms, how they vary, and how they are affected by life events

INTRODUCTION

A critical appraisal of the literature regarding female urethral function and dysfunction is needed in light of recent evidence showing the urethra's role in causing stress and urge urinary incontinence.

METHODS

An evidence assessment was conducted using selected articles from the literature that contained mechanistic data on factors affecting urethral function and failure.

RESULTS

Maximal urethral closure pressure (MUCP) is 40% lower in stress urinary incontinence (SUI) than normal controls. Evidence from five women shows relatively equal contributions to MUCP from striated/smooth muscle, vascular-plexus, connective tissue. MUCP varies twofold in individuals of similar age and declines 15% per decade even in nulliparous women. Age explains 57% of the variance in MUCP. This parallels with striated/smooth muscle loss and reduced nerve density. Factors influencing pressure variation minute-to-minute and decade-to-decade are poorly understood. Connective tissue changes have not been investigated. MUCP in de novo SUI persisting 9-months postpartum is 25% less than in age and parity-matched controls. Longitudinal studies do not show significant changes in urethral function after vaginal birth suggesting that changes in urethral support from birth may unmask pre-existing sphincter weakness and precipitate SUI. Mechanisms of interaction between support injury, pre-existing urethral weakness, and neuropathy are unclear.

CONCLUSION

Urethral failure is the predominant cause of SUI and a contributing factor for UUI; potentially explaining why mixed symptoms predominate in epidemiological studies. Age-related striated muscle loss and differences between women of similar age are prominent features of poor urethral closure. Yet, connective tissue changes, vasculature function, and complex interactions among factors are poorly understood.

Evaluation of the female bladder neck and urethra using MRI with fiber tractography: Prospective study on a large cohort of continent women

AIMS

To prospectively evaluate the performance of a last generation magnetic resonance imaging (MRI) device with tractography to identify the normal female urethral sphincters in terms of morphology and quantification on a large cohort of continent women.

METHODS

We have recorded the data of 75 continent women who underwent a diffusion tensor imaging (DTI) sequence with fiber tractography during a pelvic MR examination. Three groups of age were analyzed in terms of color fiber tracking quality and quantitative parameters (fractional anisotropy [FA] and mean diffusibility [MD]). Statistical analysis was done for the qualitative assessment using weighted kappa statistics of Cohen and for the quantitative parameters using a non-parametric Kruskal-Wallis test.

RESULTS

For all cases, fiber-tracking resulted in a satisfactory representation of the complexity of the orientation of the fibers. The interobserver concordance of qualitative data was substantial, calculated at 0.78 (confidence interval: 0.71-0.85). For FA, there was no statistically significant difference with the age between the three urethral segments (p > 0.05). However, we registered a significant difference inside each group between the different segments (p < 0.05), corresponding to different orientation of fibers. For MD, we have found a statistically significant difference both between levels inside each group and according the age, meaning a variation of the water mobility for each type of musculature and with age (p < 0.05).

CONCLUSION

DTI with fiber tractography performed on a recent MR unit is a robust method for the three-dimensional visualization of the details and connections of the urethral female sphincters. Quantitative variations with age need to be considered.

Symptomatic pelvic floor disorders and its associated factors in South-Central Ethiopia

Introduction

Pelvic floor disorders (PFD) are gynecologic health problems containing a wide variety of clinical problems; the most prevalent problems are pelvic organ prolapse, fecal incontinence, and urinary incontinence. It is a significant women’s health problem for both developed and developing countries. One in five women in Ethiopia experiences at least one major type of pelvic floor disorders. Despite the severity of the problem, due attention was not given, and no study has been conducted on pelvic floor disorders in the Gurage Zone.

Objective

To determine the prevalence and associated factors of symptomatic pelvic floor disorders among women living in Gurage Zone, SNNPR, Ethiopia, 2020.

Methodology

Community-based cross-sectional study was conducted from February to March 2020 among 542 women residing in the Gurage Zone. A multi-stage sampling method was used to select the participants. Interviewer administered, pretested questionnaires containing questions related to pelvic organ prolapse, urinary, and fecal incontinence was used. The urinary incontinence severity index questionnaire was used to assess the severity of urinary incontinence. Epi-Info x7 was used to record data, and SPSS was used to analyze the data. Binary logistic regression with 95% CI was used to explore the relationship between PFD and other independent variables. After multivariable logistic regression analysis variables with P-value less than 0.05 was used to determine significant association.

Result

A total of 542 participants were included in this study. Overall, 41.1% of the participants reported one or more symptoms of pelvic floor disorders. Urinary incontinence had the highest prevalence (32.8%), followed by pelvic organ prolapse (25.5%) and fecal incontinence (4.2%). History of weight lifting >10 Kg (AOR = 3.38; 95% CI: 1.99, 5.72), ≥5 vaginal delivery (AOR = 11.18; 95% CI: 1.53, 81.58), and being in menopause (AOR = 3.37; 95% CI: 1.40, 8.07) were identified as possible contributing factors in the development of a pelvic floor disorders.

Conclusion

The prevalence of symptomatic PFD was higher compared to other similar studies in Ethiopia. Heavy weight lifting, repetitive vaginal deliveries and menopause were factors significantly associated with PFD. Expansion of technologies and building basic infrastructures, health education on kegel exercise and promotion of family planning should be considered as a prevention strategy.

The pathophysiology of stress urinary incontinence: a systematic review and meta-analysis

Introduction and hypothesis

To evaluate the evidence for pathologies underlying stress urinary incontinence (SUI) in women.

Methods

For the data sources, a structured search of the peer-reviewed literature (English language; 1960–April 2020) was conducted using predefined key terms in PubMed and Embase. Google Scholar was also searched. Peer-reviewed manuscripts that reported on anatomical, physiological or functional differences between females with signs and/or symptoms consistent with SUI and a concurrently recruited control group of continent females without any substantive urogynecological symptoms. Of 4629 publications screened, 84 met the inclusion criteria and were retained, among which 24 were included in meta-analyses.

Results

Selection bias was moderate to high; < 25% of studies controlled for major confounding variables for SUI (e.g., age, BMI and parity). There was a lack of standardization of methods among studies, and several measurement issues were identified. Results were synthesized qualitatively, and, where possible, random-effects meta-analyses were conducted. Deficits in urethral and bladder neck structure and support, neuromuscular and mechanical function of the striated urethral sphincter (SUS) and levator ani muscles all appear to be associated with SUI. Meta-analyses showed that observed bladder neck dilation and lower functional urethral length, bladder neck support and maximum urethral closure pressures are strong characteristic signs of SUI.

Conclusion

The pathology of SUI is multifactorial, with strong evidence pointing to bladder neck and urethral incompetence. While there is also evidence of impaired urethral support and levator ani function, standardized approaches to measurement are needed to generate higher levels of evidence.

Pelvic floor muscle function and quality of life in postmenopausal women with and without pelvic floor dysfunction

INTRODUCTION

This study aims to compare pelvic floor muscle (PFM) function in postmenopausal women with and without pelvic floor dysfunction (PFD) and the relation between PFM function and quality of life.

MATERIAL AND METHODS

A case-control study with 216 postmenopausal women with (n = 126) and without (n = 90) PFD. PFM function was assessed by digital vaginal palpation using the PERFECT scale. Specific quality of life was evaluated using the King's Health Questionnaire for women with urinary incontinence and the Prolapse Quality-of-Life Questionnaire for women with pelvic organ prolapse. We analyzed women with PFD into two categories: Oxford's grade ≤2 or ≥3 using a chi-squared test.

RESULTS

Out of 126 womem with PFD 44 (34.9%) presented stress urinary incontinence, 21 (16.6%) had pelvic organ prolapse and 61 (48.4%) had urinary incontinence + pelvic organ prolapse. Strength had a median value 2 (0-5) in all women studied and most of them had insufficient strength, reduced endurance and repetition without statistical difference between groups. Incontinent women with strength ≤2 had worse perception of general health domain of King's Health Questionnaire (p = 0.007). No association was found between PFM function and Prolapse Quality-of-Life Questionnaire.

CONCLUSIONS

PFM function assessed by bidigital palpation in postmenopausal women was not sufficiently sensitive to differentiate between women with vs. women without PFM dysfunction and was not related with specific quality of life in women with urinary incontinence and pelvic organ prolapse, respectively. These data should be used to reinforce the widespread recommendation that PFM training is essencial in PFD treatment.

Do urodynamics provide a better understanding of voiding disorders in women over 80?

AIMS

Population ageing has as consequence an increasing number of women older than 80 years with lower urinary tract symptoms (LUTS). Despite old age, urodynamic study is often performed to diagnose the cause of LUTS. Our purpose is to discuss the contribution of urodynamics to manage that population.

METHODS

Urodynamic studies of 169 consecutive women older than 80 years, respectively 124 non-neurological (non-N) and 45 neurological (N), were retrospectively analysed.

RESULTS

Number of co-morbidities was lower in non-N (2.5 vs. 3.1) with predominance of cardiovascular and endocrinology while musculo-skeletal, cognitive and previous pelvic surgery predominated in N. Among main complaint, incomplete retention or dysuria was more frequent in N while incontinence and frequency were predominant in non-N. More frequent urodynamic diagnosis (UD) was "normal" i.e. non contributive (25.0%) and intrinsic sphincter deficiency (ISD=21.7%) in non-N, detrusor overactivity (DO=42.2%) and detrusor underactivity (DU=38.8%) in N. In non-N, there were 94 treatment proposals based on the complaint when UD was "normal" and on UD for DO, DU and ISD. In N, treatment proposals were mainly prompted voiding or self-catheterization based on DU diagnosis.

CONCLUSION

Usefulness of urodynamics to manage LUT dysfunction in women older than 80 y is greatly dependent on their neurological status. In non-neurological women this is non debatable but proposed treatment needs to take into account existing co-morbidities. In neurological women the main usefulness is to unmask DU and to propose the best management in order to avoid complete retention.

LEVEL OF EVIDENCE

4.

Urethral function and histopathology in aged female rats as a stress urinary incontinence model

OBJECTIVE

Stress urinary incontinence (SUI) is a common disease condition in elderly women, suggesting that its etiology may be linked to aging. To investigate the hypothesis that urethral dysfunction and histopathological changes are possible contributors to SUI in elderly women, several parameters of urethral function, as well as histological parameters, were compared between young and aged rats.

METHODS

Virgin female rats were examined at 3 different ages, namely 3, 12, and 24 months, corresponding to young, middle-aged, and aged rats, respectively. Urethral function was assessed by measuring the leak point pressure (LPP), pudendal nerve stimulation (PNS)-induced elevation in urethral pressure, and phenylephrine-induced increase in urethral perfusion pressure (UPP). Histopathological assessments were performed following hematoxylin and eosin (HE), Masson's trichrome, and immunofluorescence staining of urethral tissue.

RESULTS

LPP of aged rats was significantly reduced compared to that of both young and middle-aged rats. PNS-induced elevation in urethral pressure in aged rats was also significantly lower than that in young rats. In contrast, there were no significant differences in the phenylephrine-induced increase in UPP between young and aged rats. Connective tissue area in the external urethral sphincter (EUS) layer was increased in aged rats, whereas the smooth muscle layer was histologically similar to that in young rats. The number of EUS fibers was significantly reduced in aged rats, whereas the cross-sectional area of EUS fibers increased from differed compared with young rats.

CONCLUSION

We have demonstrated age-related changes in EUS function and morphology in the rat urethra, which are considered to be etiological risk factors for SUI in humans.

Stress urinary incontinence: What, when, why, and then what?

Stress urinary incontinence (SUI) has a significant impact on the quality of life for many women. Most women do not seek medical attention for this condition. Treatment for this problem includes initial conservative therapies and then surgery is an option. More than 200 surgical procedures have been described in the literature for the treatment of stress incontinence. The gold-standard surgical treatment of SUI in patients with a mobile bladder neck and normally functioning urethra has been accomplished through a retropubic approach using either a Burch or Marshall-Marchetti-Krantz procedure. By the absolute success of Trans obturator tape (TOT) application in treatment of SUI and the niche it has created for itself in the maze of treatment modalities available for SUI, there seems to be little doubt that TOT is all set to become the new Gold Standard for treatment of SUI in times to come. It is difficult to imagine any further improvements in the midurethral sling procedures or surgeries for SUI. However 10 years ago, no one could have imagined the progress and development that has been seen over these few short years in the treatment of SUI. The future may hold promise in technologies such as stem cells that may be injected in or around the urethral support structures and provide regeneration of the lacking support structures. What so ever, it's definitely time to provide millions of women with knowledge that empowers them to make lifestyle changes to decrease their risk of SUI and to understand the reality that they are not alone if they have SUI.

Impact of castration with or without alpha-tocopherol supplementation on the urethral sphincter of rats

OBJECTIVE

To analyze the impact of low levels of testosterone induced by orchiectomy and the effect of alpha-tocopherol supplementation on oxidative stress in the urethral sphincter.

MATERIALS AND METHODS

Forty male Wistar rats weighing 250-300 g were divided into four groups with 10 each: Sham group; Orchiectomy group: bilateral orchiectomy; Orchiectomy-pre-Tocopherol group: bilateral orchiectomy preceded by alpha-tocopherol supplementation for four weeks; Orchiectomy-full-Tocopherol group: bilateral orchiectomy with alpha-tocopherol supplementation for four weeks preceding the procedure and for eight weeks afterwards. At the protocol end, animals were euthanized and had the sphincter analyzed stereologically focusing on collagen and muscle fibers percentage. Oxidative stress levels were determined using 8-epi-PGF2.

RESULTS

The 8-epi-PGF2 levels were statistically higher (p < 0.0003) in the Orchiectomy group compared to others groups while Sham and Orchiectomy-full-Tocopherol groups presented statistically similar values (p = 0.52). Collagen volumetric densities were significantly lower in Sham and Orchiectomy-full-Tocopherol groups (p < 0.022). Sham group presented statistically greater muscle fiber percent.

CONCLUSION

Castration caused oxidative stress in the urethral sphincter complex, with increased collagen deposition. Alpha-tocopherol had a protective effect and its supplementation for twelve weeks provided the greatest protection.

Urinary incontinence in the aging female: etiology, pathophysiology and treatment options

Not only does the prevalence of incontinence increase with age, but the incidence does as well, in no small part due to the greater recognition of its signs and symptoms and the significant negative impact on quality of life. Elderly women differ from their younger counterparts by the presence of several physiologic changes in the urinary tract, as well as the presence of concomitant morbidity and polypharmacy. While the elderly have the same treatment options as younger women, they may experience a greater incidence of adverse events due to urologic and nonurologic factors. The objective of this article is to elucidate the unique changes in the elderly population and summarize the treatment options.

Histologic study of urethral extracellular matrix and collagen from aging and long-term alloxan-induced diabetic male rats

OBJECTIVES

To evaluate the histological alterations of extracellular matrix in long-term alloxan-induced diabetes and aging urethras of male rats with descriptions of total connective tissue, muscle layer and collagen types I and III relative amounts.

METHODS

Histologic evaluations were performed in 3 animal groups: group 1, 8 weeks old; group 2, 44 weeks old; and group 3, 44 weeks old with alloxan-induced diabetes. The muscle layer thickness, extracellular matrix fibrosis, and collagen were quantified on digital images of the urethral samples.

RESULTS

A higher total thickness and muscle layer thickness and higher connective tissue and collagen content were observed in the urethras of group 3. No changes in the collagen type III/I ratio were found in the urethra of groups 2 and 3.

CONCLUSIONS

Our results suggest that the morphologic alterations of the urethra should also be considered in long-term studies of diabetic lower urinary tract dysfunction. These morphologic alterations due to diabetes differ from the changes induced by aging itself and could represent a final stage in decompensate urethras. Further studies are necessary to establish the real influence of the urethral morphologic changes on lower urinary tract diabetes dysfunction.

Sexual steroids in urogynecology

The decline in sex hormone levels that accompanies the menopause has substantial effects on the tissues of the urogenital system, leading to atrophic changes. These changes can have negative effects on sexual and urinary function. The authors evaluate the repercussion of hypoestrogenism and sexual steroids on some elements of the pelvic floor and lower urinary tract. They summarize their research work and review significant published papers. They emphasize the changes in urinary mucosae, periurethral vessels, muscular layer, connective tissue, gene expression, autonomic nervous system receptors, as well as the main clinical aspects involved.

Urethral sphincter morphology and function with and without stress incontinence

PURPOSE

Using magnetic resonance images we analyzed the relationship between urethral sphincter anatomy, urethral function and pelvic floor function.

MATERIALS AND METHODS

A total of 103 women with stress incontinence and 108 asymptomatic continent controls underwent urethral profilometry, urethral axis measurement with a cotton swab, vaginal closure force measurement with an instrumented speculum and magnetic resonance imaging. Striated urogenital sphincter length was determined and its thickness was measured in the proximal sphincter, where its circular shape enables estimation of striated urogenital sphincter area. A length-area index was calculated as a proxy for volume.

RESULTS

The striated urogenital sphincter in women with stress incontinence was 12.5% smaller than that in asymptomatic continent women (mean +/- SD length-area index 766.4 +/- 294.3 vs 876.2 +/- 407.3 mm(3), p = 0.04). The groups did not differ significantly in striated urogenital sphincter length (13.2 +/- 3.4 vs 13.7 +/- 3.9 mm, p = 0.40), thickness (2.83 +/- 0.8 vs 3.11 +/- 1.4 mm, p = 0.09) or area (59.1 +/- 18.4 vs 62.9 +/- 24.7 mm(2), p = 0.24). Striated urogenital sphincter length and area, and the length-area index were associated during voluntary pelvic muscle contraction with more urethral axis elevation and increased vaginal closure force augmentation.

CONCLUSIONS

A smaller striated urogenital sphincter is associated with stress incontinence and poorer pelvic floor muscle function.

Urethral circular smooth muscle in young and old women

OBJECTIVE

The purpose of this study was to determine whether thickness, fiber count, and density of urethral circular smooth muscle (CSM) differ in young and old women.

STUDY DESIGN

Mid urethral hemiaxial sections from female cadavers aged 20-39 years (n = 12) and 70-89 years (n = 16) were stained for smooth muscle alpha actin. The CSM was studied at 0 degrees (pubic bone side) and 180 degrees (vaginal side) and in between at 45, 90, and 135 degrees. CSM layer width was measured; fibers were counted; density was calculated (fiber count/layer width).

RESULTS

Density of urethral CSM was 25%-50% higher in specimens aged 20-39 years, compared with those aged 70-89 years. Differences were observed at 0, 135, and 180 degrees. In the younger group, higher fiber counts were observed at 135 and 180 degrees, and the CSM layer was thinner but not significantly so.

CONCLUSION

The density of CSM was lower among older women, which may account for age-related decline in urethral closure pressure.

Long term evaluation of functional and morphological bladder alterations on alloxan-induced diabetes and aging: experimental study in rats

PURPOSE: to evaluate structural and functional effects of Alloxan- induced diabetes and aging on bladder of rats. METHODS: evaluations were performed in three groups: A - 8 weeks of age, B - 44 weeks of age, C - 44 weeks of age with alloxan-induced diabetes. Muscle layer thickness, extracellular matrix fibrosis and collagen were quantified on digital images of bladder samples. Cystometric evaluations before surgical vesical denervation (SVD), included maximum cystometric capacity (MCC), maximum bladder pressure (MBP), bladder contraction frequency (VCF), duration of bladder contraction (DC), threshold pressure (TP) and bladder compliance (BC). After SVD, maximum cystometric capacity (MCC), BC and maximum urethral closing pressure (MUCP) were also measured. RESULTS: Reduced extracellular matrix fibrosis concentration and contraction strength were found in the bladders of group C. Before SVD, bladder compliance was not different between groups. Alterations were observed in MCC after SVD. CONCLUSIONS: We did not notice smooth muscle hypertrophy in Alloxan-induced diabetic rats after 44 weeks. There was alteration in the total and relative amount of fibrosis and collagen. The cystometric studies support the idea that this morphological alterations are important to determine the different bladder functional patterns found in the aging and the Alloxan-induced diabetic animals.

Impact of pregnancy and childbirth on female rats’ urethral nerve fibers

This study aims to evaluate the urethral nerve fibers of adult female rats during pregnancy and after vaginal birth, cesarean section or simulated birth trauma. For immunohistochemical analysis of nerve fibers, 70 female rats were distributed in seven groups of ten female rats: group 1, control; group 2, pregnant; group 3, cesarean section; group 4, vaginal birth; group 5, virgin female rats with simulated birth trauma; group 6, cesarean section followed by simulation of birth trauma; and group 7, vaginal birth followed by simulation of birth trauma. The number of nerve fibers in groups 1, 2, and 3 were significantly higher than the other groups. Pregnancy and cesarean section did not cause alterations in the nerve fibers number. Vaginal birth and simulated birth trauma significantly decreased the number of nerve fibers in the female rats' middle urethra.

Effects of Aging on Lower Urinary Tract and Pelvic Floor Function in Nulliparous Women

OBJECTIVE

To evaluate the effects of aging, independent of parity, on pelvic organ and urethral support, urethral function, and levator function in a sample of nulliparous women.

METHODS

A cohort of 82 nulliparous women, aged 21-70 years, were recruited from the community through advertisements. Subjects underwent pelvic examination using pelvic organ prolapse quantification, urethral angles by cotton-tipped swab, and multichannel urodynamics and uroflow. Vaginal closure force was quantified using an instrumented vaginal speculum. Subjects were grouped into five age categories and analyses performed using t tests, Fisher exact tests, Kruskal-Wallace, and Pearson correlation coefficients. Multiple linear regression modeling was performed to adjust for factors that might confound the results of our primary outcomes.

RESULTS

Increasing age was associated with decreasing maximal urethral closure pressure (r=-0.758, P<.001) with a 15-cm-H(2)O decrease in pressure per decade. Pelvic organ support as measured by pelvic organ prolapse quantification did not differ by age group. Levator function as measured by resting vaginal closure force and augmentation of vaginal closure force also did not change with increasing age.

CONCLUSION

In a sample of nulliparous women between 21 and 70 years of age maximal urethral closure pressure in the senescent urethra was 40% of that in the young urethra; increasing age did not affect clinical measures of pelvic organ support, urethral support, and levator function.

LEVEL OF EVIDENCE

III.

A contextual model of pelvic floor muscle defects in female stress urinary incontinence: a rationale for physiotherapy treatment

On the basis of the current literature, we describe a model of structural defects in stress urinary incontinence (SUI) and how physiotherapy for SUI can affect each component of the model with reference to the relevant anatomy and pathophysiology. This model of SUI involves four primary structural defects: (1) increased tonic stress on the pelvic fascia due to pelvic floor muscle (PFM) tears; (2) fascial tearing due to PFM denervation; (3) fascial weakness resulting from tears; and (4) inefficient PFM contraction due to altered motor control. These four components interact to collectively weaken urethral closure and allow urine leakage under conditions of increased intra-abdominal pressure. Physiotherapy can strengthen the PFM and may improve the efficiency and/or timing of PFM contractions to reduce or eliminate SUI. It is worthwhile for motivated women with SUI to try PFM exercise therapy as a first approach to treatment. Women need to be individually instructed to ensure that they correctly perform PFM contractions and that they can monitor their own performance. Long-term, high-intensity exercise, including home exercise, is necessary to achieve maximum effect. Under these conditions the improvement in urinary continence with PFM exercise can be complete and enduring.

The impact of pregnancy and childbirth in the urethra of female rats

The aim of this study was to evaluate the modifications in the amount of collagen, muscular, and elastic fibers in the mid-urethra of adult female rats during the pregnancy and after the natural childbirth, cesarean, and after simulated trauma of childbirth. The authors evaluated the histomorphometric aspects (collagen, muscular, and elastic fibers) in the mid-urethra of 70 animals distributed in seven groups: group 1 (n = 10)--control, group 2 (n = 10)--pregnant female rats, group 3 (n = 10)--female rats submitted to cesarean, group 4 (n = 10)--female rats with natural childbirth, group 5 (n = 10)--virgin female rats with simulated trauma of childbirth, group 6 (n = 10)--female rats submitted to cesarean followed by simulation of childbirth trauma, and group 7 (n = 10)--female rats with natural childbirth followed by simulation of childbirth trauma. The average concentration of collagen and elastic fibers and the collagen/muscular fiber correlation in groups 1, 2, and 3 were similar and significantly inferior to groups 4, 5, 6, and 7. The average of muscular fibers was similar in groups 1, 2, and 3 and significantly superior to groups 4, 5, 6, and 7. Pregnancy and cesarean did not induce alterations in collagen, muscular, and elastic fibers. However, the vaginal delivery and simulation of childbirth trauma determined the decrease in muscular fibers and the increase in collagen and elastic fibers and the correlation collagen/muscular fiber.

The Aging Lower Urinary Tract

PURPOSE

Age related changes in continence and the GU system, and how they affect the management of LUT dysfunction are discussed. Guidelines are offered regarding the diagnosis and management of incontinence in the elderly population.

MATERIALS AND METHODS

Published literature and current treatment practice specific to elderly patients with LUT dysfunction were reviewed.

RESULTS

LUT symptoms in the elderly population are affected by the high prevalence of comorbidity and polypharmacy. In addition, the GU system undergoes age related changes that increase the risk of LUT dysfunction.

CONCLUSIONS

Incontinence in older persons is almost always caused by multiple factors, of which not all are directly related to the GU system. Issues such as polypharmacy, comorbidity, and the increased risk of medication side effects must be considered in planning treatment. The primary care physician and urologist or gynecologist should establish a partnership to co-manage the broad spectrum of factors affecting continence in elderly patients.

MRI morphology of the levator ani muscle, endopelvic fascia, and urethra in women with stress urinary incontinence

OBJECTIVE

To evaluate pathomorphologic changes of the levator ani muscle, endopelvic fascia, and urethra in women with stress urinary incontinence (SUI) by MRI.

STUDY DESIGN

Fifty-four women with SUI were examined by MRI (1.5T): body phased-array coil, axial and coronal proton-density-weighted sequences.

RESULTS

The urethral sphincter muscle showed a reduced thickness of its posterior portion (37%), an omega shape (13%) or higher signal intensity (50%); its abnormal configuration was associated with an increased signal intensity in 70% (p=0.001). The levator ani muscle comprised an unilateral loss of substance in 30%, a higher signal intensity in 28%, and altered origin in 19%. Central defects of the endopelvic fascia were present in 39% (n=21), lateral defects in 46%. There was a significant association between loss of the symphyseal concavity of the anterior vaginal wall and lateral fascial defects (p=0.001) and levator ani changes (p=0.016).

CONCLUSION

MRI yields findings supporting current theories on the pathogenesis of SUI.

Morphology of the suburethral pubocervical fascia in women with stress urinary incontinence: a comparison of histologic and MRI findings

To correlate MRI with histologic findings of the suburethral pubocervical fascia in women with urodynamic stress incontinence. Thirty-one women with urodynamically proven stress urinary incontinence without relevant prolapse underwent preoperative MRI. Tissue specimens obtained from the pubocervical fascia were examined immunohistochemically (types I and III collagen, smooth muscle actin) and the results compared with the MRI findings. MRI demonstrated an intact pubocervical fascia in 61.3% of the cases and a fascial defect in 38.7%. A fascial defect demonstrated by MRI was associated with a decrease in actin (P<0.09) and an increase in collagen III (P<0.01) compared to an intact fascia. In women with stress urinary incontinence, smooth muscle actin in the pubocervical fascia is decreased, changed in structure, and replaced by type III collagen. MRI allows evaluation of the pubocervical fascia and its morphologic changes.

Histochemical and contractile properties of striated muscles of urethra and levator ani of dogs and sheep

AIMS

To understand their possible importance in long- and short-term control of continence, some properties of the striated muscles of the urethra and pelvic floor (levator ani) of dogs and sheep were investigated, especially fiber types and contractile characteristics.

MATERIALS AND METHODS

Striated muscles of urethra and levator ani of 29 male and 6 female dogs and 11 male and 6 female sheep were removed and cut into strips. Some strips were frozen and stained for ATPase at pH 9.4 and 4.3 for fiber typing; others were set up in an organ bath to study contractile responses to nerve stimulation.

RESULTS

All muscles contained both type I (slow) and type II fibers, ranging from 97% type II in female greyhound urethra to 60% in female sheep levator ani. For each muscle, there were fewer type II muscles in sheep than in dog. The diameters of the urethral fibers were about 60% of the levator ani in dogs and 34% in sheep. Contraction of the urethral muscle was faster than for levator ani and declined to about 80% of the peak, 500 msec after the beginning of stimulation at 20 Hz. The levator ani contraction rose to a steady level as long as stimulation continued.

CONCLUSIONS

Both the levator ani and urethral striated muscles contain slow and fast fiber types. The levator ani muscles are capable of sustained contraction with rapid onset which will produce long-term closure of the urethra. The circular urethral muscle contraction was faster but less well maintained.

The urethra and its supporting structures in women with stress urinary incontinence: MR imaging using an endovaginal coil

OBJECTIVE

The objective of this study was to evaluate the urethra and its supporting structures in patients with stress urinary incontinence using MR imaging with an endovaginal coil.

SUBJECTS AND METHODS

We reviewed MR images obtained using an endovaginal coil in 63 patients with stress urinary incontinence and in 16 continent women. We compared the two groups for the thickness of the striated muscle, smooth muscle, and mucosa-submucosa of the urethra; degree of asymmetry of the puborectalis muscle; frequency of distortion in the periurethral, paraurethral, and pubourethral ligaments; degree of the vesicourethral angle; and dimension of the retropubic space. Using the status of the urethra and its supporting structures as our basis, we scored the risk of stress urinary incontinence for each woman on a scale of 0-5.

RESULTS

The striated muscle layer of the urethra was thinner in the group with stress urinary incontinence (mean +/- SD, 1.9 +/- 0.5 mm) than that in the continent group (2.6 +/- 0.4 mm) (p < 0.001). A high degree of asymmetry of puborectalis muscle (>1.5) was more frequent in the group with stress urinary incontinence (29%) than in the continent group (0%) (p = 0.015). Supporting ligaments were more frequently distorted in the incontinent group than in the continent group. Distorted periurethral ligaments were found in 56% of the patients with stress urinary incontinence versus 13% of the women who were continent; distorted paraurethral ligaments were found in 83% of the patients with stress urinary incontinence versus 19% of the women who were continent; and distorted pubourethral ligaments were found in 54% of the patients with stress urinary incontinence versus 19% of the women who were continent (p < 0.05). The group with stress urinary incontinence had a greater vesicourethral angle (148 degrees vs 125 degrees ) and larger retropubic space (7.5 vs 5.1 mm) than did the women who were continent (p < 0.05). The score for the risk of stress urinary incontinence was higher in the group with stress urinary incontinence (3.3 +/- 1.4) than in the women who were continent (1.0 +/- 1.2) (p < 0.001).

CONCLUSION

MR imaging with an endovaginal coil revealed significant morphologic alterations of the urethra and supporting structures in patients with stress urinary incontinence.

Computerised morphometric study of the paraurethral tissue in young and elderly women

AIM

Changes in structural support of the urethra and bladder neck have been proposed to be among the most important factors in the pathogenesis of stress urinary incontinence. In this context, we histologically investigated the paraurethral area in continent women to quantify the relative distribution of connective tissue, smooth muscle, vessels, nerves, and striated muscle. Previously published literature gives only descriptive evaluations of the relative distribution of these tissue components.

METHODS

We used a computerised morphometric method, which allowed us to estimate the paraurethral tissue distribution in a more objective way. The material was obtained by dissection during autopsy in five premenopausal and five postmenopausal women.

RESULTS

Paraurethral tissue consisted of 56% connective tissue (SD, 5%), 30% smooth muscle (SD, 5%), 11% blood vessel (SD, 6%), 2% striated muscle (SD, 3%), and 1% nerves (SD, 1%). We also found that the distribution of different tissue components along the length of the urethra did not differ at a statistically significant level. Furthermore, there was a statistically significant difference in the amount of connective tissue and blood vessels in the postmenopausal women compared with the premenopausal women.

CONCLUSIONS

The present study shows that the paraurethral area is built of heterogeneous tissue with small changes in its composition along the course of urethra. Increase in connective tissue was found to be the dominating change in the process of ageing.

Why do women have voiding dysfunction and de novo detrusor instability after colposuspension?

OBJECTIVE

To investigate the causes of voiding dysfunction and new detrusor instability after colposuspension.

DESIGN

Prospective, observational study.

SETTING

Urogynaecology unit, district general hospital.

POPULATION

Seventy-seven women undergoing colposuspension for genuine stress incontinence.

METHODS

The following factors were investigated: 1. bladder neck elevation by magnetic resonance imaging before and after surgery; 2. urethral compression by measuring bladder neck approximation to the pubis with magnetic resonance imaging after surgery (anterior compression) and the distance between the medial stitches during surgery (lateral compression); 3. clinical and urodynamic factors.

MAIN OUTCOME MEASURES

1. Post-operative voiding function (i.e. first day of voiding and day of catheter removal); 2. objective evidence of detrusor instability three months post-operatively.

RESULTS

Pre-operative peak flow rate (P = 0.004), straining during voiding (P = 0.005), increasing age (P < 0.001), operative elevation (P < 0.001) and anterior urethral compression (P = 0.001) were associated with the number of days of post-operative catheterisation. Increasing age (P = 0.02), previous bladder neck surgery (P = 0.04), operative elevation (P = 0.049) and anterior urethral compression (P < 0.001) were associated with detrusor instability at three months.

CONCLUSION

Surgical factors (bladder neck elevation and compression) are associated with voiding dysfunction and detrusor instability after colposuspension. These findings have implications for prevention.

Age effects on urethral striated muscle. I. Changes in number and diameter of striated muscle fibers in the ventral urethra

OBJECTIVE

This study was undertaken to test the null hypothesis that the number of striated muscle fibers in the ventral wall of the female urethra remains constant with increasing age.

STUDY DESIGN

The urethra and surrounding tissues from 25 female cadavers, mean age 52 years (+/-SD 18, range 15-80 years), were selected for this study. Each specimen was divided along the midsagittal plane, and a Masson trichrome histologic section was prepared. A systematic count of striated muscle fibers in the ventral wall was then obtained at each decile of urethral length.

RESULTS

A decrease in the total number of fibers within the sampled area was found with increasing age. The mean of the total fibers across all urethrae was 17,423 (+/-SD 9,624, range 4,788-35,867). Over the life span, an average of 364 fibers (2%) were lost per year (95% CI 197-531; P <.001). Mean fiber density was 671 (+/- SD 296, range 228-1374) fibers/mm2 and decreased by 13 fibers/mm2 per year (95% CI 8-17; P <.001). The mean lesser fiber diameter was 24 microm and did not change significantly with age ( P =.3).

CONCLUSIONS

The number and density of urethral striated muscle fibers decline with age.

Contractile properties of urethral smooth muscles of young and aged female dogs: morphological and pharmacological aspects

BACKGROUND

Alpha1-adrenoceptors are highly concentrated in the urethral smooth muscles and may play an important role in the contraction of this area. However, detailed examinations of age-related changes of the properties of urethral smooth muscle have rarely been undertaken.

METHODS

The contractile properties of urethras from young non-parous and old parous female beagles were determined with a urethral function study, macroscopic autoradiography for urethras using [3H]-labeled tamsulosin and morphometry of the urethral muscles.

RESULTS

The antagonistic effect (pA2) of prazosin for norepinephrine was 7.76+/-0.13 in young dogs and 7.62+/-0.06 in aged dogs. The specific binding of [3H]-tamsulosin (a relatively selective alpha1A-adrenoceptor antagonist) was recognized diffusely in proximal urethras with in vitro autoradiography. The density of binding in smooth muscles was approximately 60 and 40% in circular longitudinal layers, respectively, for both dogs.

CONCLUSIONS

The female canine urethra had alpha1A, and alpha1L-adrenoceptors. No age-related changes were seen in the function of the proximal urethra, distribution of alpha1-adrenoceptor binding sites and smooth muscle densities.

Asymptomatic bacteriuria and inflammatory response to urinary tract infection of elderly ambulatory women in nursing homes

BACKGROUND

Bacteriuria > or = 10(5) CFU/ml is evidence of urinary tract infection in the absence of associated signs or symptoms. The presence of pyuria with asymptomatic bacteriuria established the response of elderly women against microorganisms capable of causing invasiveness or tissue injury of the urinary tract.

METHODS

The association between bacteriuria and pyuria was determined in 178 elderly, ambulatory women without symptoms of urinary tract infection in seven nursing homes. Urine culture results were subsequently analyzed in conjunction with absolute leukocyte count in urine. In this cross-sectional study, asymptomatic bacteriuria in elderly women was classified with and without pyuria.

RESULTS

The prevalence of asymptomatic bacteriuria was found in 44 (24.7%) elderly women. The presence of pyuria had a sensitivity of 63.6% for bacteriuria and a specificity of 91%. The positive predictive value for the presence of pyuria predicting those with bacteriuria was 70%, and the negative predictive value for the absence of pyuria predicting those without bacteriuria was 88.4%. Escherichia coli was the most common organism isolated in 81.8% of the women.

CONCLUSIONS

Bacteriuria > or 10(5) CFU/ml associated with pyuria was detected in 77% of elderly women with asymptomatic urinary tract infections. Bacteriuria of < 10(5) CFU/ml with pyuria proves less sensitive as an indicator of urinary tract infection. Elderly women with pyuria but without bacteriuria should be studied for other causes of urinary tract inflammation.

Normal pelvic floor physiology

This article outlines the normal physiology of the female pelvic floor, including normal urinary storage and voiding, normal colorectal storage, and defecation. Physiologic changes during a woman's lifetime that may affect bladder and bowel function are also considered. An important framework for understanding the normal physiology of the female pelvic floor is provided, so the reader may gain a more thoughtful approach to the recognition and treatment of pelvic floor pathophysiology.

Normal pelvic floor anatomy

The anatomy of the pelvic floor includes structures responsible for active and passive support of the urethrovesical junction, vagina, and anorectum. Intrinsic and extrinsic properties of the urethrovesical neck and anorectum allow maintenance of urinary and anal continence at rest and with activity. Damage to these structures may lead to loss of support and loss of normal function of the urethra, bladder, and anorectum. Over time, this damage can result in isolated or combined pelvic organ prolapse, urinary incontinence, and anal incontinence.

The pathophysiology of stress urinary incontinence in women and its implications for surgical treatment

Stress urinary incontinence is a symptom that arises from damage to the muscles, nerves, and connective tissue of the pelvic floor. Urethral support, vesical neck function, and function of the urethral muscles are important determinants of continence. The urethra is supported by the action of the levator ani muscles through their connection to the endopelvic fascia of the anterior vaginal wall. Damage to the connection between this fascia and muscle, loss of nerve supply to the muscle, or direct muscle damage can influence continence. In addition, loss of normal vesical neck closure can result in incontinence despite normal urethral support. Although the traditional attitude has been to ignore the urethra as a factor contributing to continence, it does play a role in determining stress continence since in 50% of continent women, urine enters the urethra during increases in abdominal pressure, where it is stopped before it can escape from the external meatus. Perhaps one of the most interesting yet least acknowledged aspects of continence control concerns the coordination of this system. The muscles of the urethra and levator ani contract during a cough to assist continence, and little is known about the control of this phenomenon. That operations cure stress incontinence without altering nerve or muscle function should not be misinterpreted as indicating that these factors are unimportant.