Stress urinary incontinence: relative importance of urethral support and urethral closure pressure

Smooth Muscle Progenitor Cells Derived From Human Pluripotent Stem Cells Induce Histologic Changes in Injured Urethral Sphincter

: Data suggest that myoblasts from various sources, including bone marrow, skeletal muscle, and adipose tissue, can restore muscle function in patients with urinary incontinence. Animal data have indicated that these progenitor cells exert mostly a paracrine effect on the native tissues rather than cell regeneration. Limited knowledge is available on the in vivo effect of human stem cells or muscle progenitors on injured muscles. We examined in vivo integration of smooth muscle progenitor cells (pSMCs) derived from human pluripotent stem cells (hPSCs). pSMCs were derived from a human embryonic stem cell line (H9-ESCs) and two induced pluripotent stem cell (iPSC) lines. pSMCs were injected periurethrally into urethral injury rat models (2 × 10⁶ cells per rat) or intramuscularly into severe combined immunodeficiency mice. Histologic and quantitative image analysis revealed that the urethras in pSMC-treated rats contained abundant elastic fibers and thicker muscle layers compared with the control rats. Western blot confirmed increased elastin/collagen III content in the urethra and bladder of the H9-pSMC-treated rats compared with controls. iPSC-pSMC treatment also showed similar trends in elastin and collagen III. Human elastin gene expression was not detectable in rodent tissues, suggesting that the extracellular matrix synthesis resulted from the native rodent tissues rather than from the implanted human cells. Immunofluorescence staining and in vivo bioluminescence imaging confirmed long-term engraftment of pSMCs into the host urethra and the persistence of the smooth muscle phenotype. Taken together, the data suggest that hPSC-derived pSMCs facilitate restoration of urethral sphincter function by direct smooth muscle cell regeneration and by inducing native tissue elastin/collagen III remodeling.

SIGNIFICANCE

The present study provides evidence that a pure population of human smooth muscle progenitor cells (pSMCs) derived from human pluripotent stem cells (hPSCs) (human embryonic stem cells and patient induced pluripotent stem cells) restores urethral sphincter function by two mechanisms: modulation of extracellular matrix protein metabolism in vivo and pSMC proliferation and differentiation into smooth muscle cells to regenerate the muscle layer in the lower urinary tract. These findings on the in vivo effects of human pSMCs should aid in optimizing regenerative therapies using human myoblasts.

Association of urinary and anal incontinence with measures of pelvic floor muscle contractility

OBJECTIVE

To assess the association between clinical and sonographic measures of pelvic floor muscle (PFM) function and symptoms of urinary and anal incontinence (AI).

METHODS

This was a retrospective study of women seen at a tertiary urogynecological unit. All women had undergone a standardized interview, clinical examination including Modified Oxford Scale (MOS) grading, urodynamic testing and four-dimensional translabial ultrasound (TLUS). Cranioventral shift of the bladder neck (BN) and reduction in the hiatal anteroposterior (AP) diameter were measured using ultrasound volumes acquired on maximal PFM contraction, blinded against all clinical data.

RESULTS

Data from 726 women with a mean age of 56 ± 13.7 (range, 18-88) years and a mean body mass index of 29 ± 6.1 (range, 17-55) kg/m(2) were analyzed. Stress (SI) and urge (UI) urinary incontinence were reported by 73% and 72%, respectively, and 13% had AI. Mean MOS grade was 2.4 ± 1.1 (range, 0-5). Mean cranioventral BN shift on TLUS was 7.1 ± 4.4 (range, 0.3-25.3) mm; mean reduction in AP hiatal diameter was 8.6 ± 4.8 (range, 0.3-31.3) mm. On univariate analysis, neither MOS nor TLUS measures were strongly associated with symptoms of urinary incontinence or AI; associations were non-significant except for BN displacement/SI (7.3 mm vs 6.5 mm; P = 0.028), BN displacement/UI (6.85 vs 7.75; P = 0.019), hiatal AP diameter/AI (9.6 mm vs 8.5 mm; P = 0.047) and MOS/SI (2.42 vs 2.19; P = 0.013).

CONCLUSIONS

In this large retrospective study we did not find any strong associations between sonographic or palpatory measures of PFM function and symptoms of urinary incontinence or AI. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Can we predict urinary stress incontinence by using demographic, clinical, imaging and urodynamic data?

OBJECTIVE

It has been claimed that urethral hypermobility and resting urethral pressure can largely explain stress incontinence in women. In this study we tried to replicate these findings in an unselected cohort of women seen for urodynamic testing, including as many potential confounders as possible.

STUDY DESIGN

This study is a retrospective analysis of data obtained from 341 women. They attended for urodynamic testing due to symptoms of pelvic floor dysfunction. We excluded from the analysis women with a history of previous anti-incontinence and prolapse surgery. All patients had a standardised clinical assessment, 4D transperineal pelvic floor ultrasound and multichannel urodynamic testing. Urodynamic stress incontinence (USI) was diagnosed by multichannel urodynamic testing. Its severity was subjectively graded as mild, moderate and severe. Candidate variables were: age, BMI, symptoms of prolapse, vaginal parity, significant prolapse (compartment-specific), levator avulsion, levator hiatal area, Oxford grading, midurethral mobility, maximum urethral pressure (MUP), maximum cough pressure and maximum Valsalva pressure reached.

RESULTS

On binary logistic regression, the following parameters were statistically significant in predicting urodynamic stress incontinence: age (P=0.03), significant rectocele (P=0.02), max. abdominal pressure reached (negatively, P<0.0001), midurethral mobility (P=0.0004) and MUP (negatively, P<0.0001). On multivariate analysis, accounting for multiple interdependencies, the following predictors remained significant: max. abdominal pressure reached (negatively, P<0.0001), cough pressure (P=0.006), midurethral mobility (P=0.003) and MUP (negatively, P<0.0001), giving an R(2) of 0.24.

CONCLUSIONS

Mid-urethral mobility and MUP are the main predictors of USI. Demographic and clinical data are at best weak predictors. Our results suggest the presence of major unrecognised confounders.

Cell Therapy for Stress Urinary Incontinence

Urinary incontinence (UI) is the involuntary loss of urine and is a common condition in middle-aged and elderly women and men. Stress urinary incontinence (SUI) is caused by leakage of urine when coughing, sneezing, laughing, lifting, and exercise, even standing leads to increased intra-abdominal pressure. Other types of UI also exist such as urge incontinence (also called overactive bladder), which is a strong and unexpected sudden urge to urinate, mixed forms of UI that result in symptoms of both urge and stress incontinence, and functional incontinence caused by reduced mobility, cognitive impairment, or neuromuscular limitations that impair mobility or dexterity. However, for many SUI patients, there is significant loss of urethral sphincter muscle due to degeneration of tissue, the strain and trauma of pregnancy and childbirth, or injury acquired during surgery. Hence, for individuals with SUI, a cell-based therapeutic approach to regenerate the sphincter muscle offers the advantage of treating the cause rather than the symptoms. We discuss current clinically relevant cell therapy approaches for regeneration of the external urethral sphincter (striated muscle), internal urethral sphincter (smooth muscle), the neuromuscular synapse, and blood supply. The use of mesenchymal stromal/stem cells is a major step in the right direction, but they may not be enough for regeneration of all components of the urethral sphincter. Inclusion of other cell types or biomaterials may also be necessary to enhance integration and survival of the transplanted cells.

Differences in pelvic floor morphology between continent, stress urinary incontinent, and mixed urinary incontinent elderly women: An MRI study

AIMS

To compare magnetic resonance imaging (MRI) of the pelvic floor musculature (PFM), bladder neck and urethral sphincter morphology under three conditions (rest, PFM maximal voluntary contraction (MVC), and straining) in older women with symptoms of stress (SUI) or mixed urinary incontinence (MUI) or without incontinence.

METHODS

This 2008-2012 exploratory observational cohort study was conducted with community-dwelling women aged 60 and over. Sixty six women (22 per group), mean age of 67.7 ± 5.2 years, participated in the study. A 3 T MRI examination was conducted under three conditions: rest, PFM MVC, and straining. ANOVA or Kruskal-Wallis tests (data not normally distributed) were conducted, with Bonferroni correction, to compare anatomical measurements between groups.

RESULTS

Women with MUI symptoms had a lower PFM resting position (M-Line P = 0.010 and PC/H-line angle P = 0.026) and lower pelvic organ support (urethrovesical junction height P = 0.013) than both continent and SUI women. Women with SUI symptoms were more likely to exhibit bladder neck funneling and a larger posterior urethrovesical angle at rest than both continent and MUI women (P = 0.026 and P = 0.008, respectively). There were no significant differences between groups on PFM MVC or straining.

CONCLUSIONS

Women with SUI and MUI symptoms present different morphological defects at rest. These observations emphasize the need to tailor UI interventions to specific pelvic floor defects and UI type in older women.

PATIENT SUMMARY

Older women with UI demonstrate different problems with their pelvic organ support structures depending on the type of UI. These new findings should be taken into consideration for future research into developing new treatment strategies for UI in older women. Neurourol. Urodynam. 35:515-521, 2016. © 2015 Wiley Periodicals, Inc.

Stress urinary incontinence animal models as a tool to study cell-based regenerative therapies targeting the urethral sphincter

Urinary incontinence (UI) is a major health problem causing a significant social and economic impact affecting more than 200million people (women and men) worldwide. Over the past few years researchers have been investigating cell therapy as a promising approach for the treatment of stress urinary incontinence (SUI) since such an approach may improve the function of a weakened sphincter. Currently, a diverse collection of SUI animal models is available. We describe the features of the different models of SUI/urethral dysfunction and the pros and cons of these animal models in regard to cell therapy applications. We also discuss different cell therapy approaches and cell types tested in preclinical animal models. Finally, we propose new research approaches and perspectives to ensure the use of cellular therapy becomes a real treatment option for SUI.

A multi-compartment 3-D finite element model of rectocele and its interaction with cystocele

We developed a subject-specific 3-D finite element model to understand the mechanics underlying formation of female pelvic organ prolapse, specifically a rectocele and its interaction with a cystocele. The model was created from MRI 3-D geometry of a healthy 45 year-old multiparous woman. It included anterior and posterior vaginal walls, levator ani muscle, cardinal and uterosacral ligaments, anterior and posterior arcus tendineus fascia pelvis, arcus tendineus levator ani, perineal body, perineal membrane and anal sphincter. Material properties were mostly from the literature. Tissue impairment was modeled as decreased tissue stiffness based on previous clinical studies. Model equations were solved using Abaqus v 6.11. The sensitivity of anterior and posterior vaginal wall geometry was calculated for different combinations tissue impairments under increasing intraabdominal pressure. Prolapse size was reported as pelvic organ prolapse quantification system (POP-Q) point at point Bp for rectocele and point Ba for cystocele. Results show that a rectocele resulted from impairments of the levator ani and posterior compartment support. For 20% levator and 85% posterior support impairments, simulated rectocele size (at POP-Q point: Bp) increased 0.29 mm/cm H2O without apical impairment and 0.36 mm/cm H2O with 60% apical impairment, as intraabdominal pressures increased from 0 to 150 cm H2O. Apical support impairment could result in the development of either a cystocele or rectocele. Simulated repair of posterior compartment support decreased rectocele but increased a preexisting cystocele. We conclude that development of rectocele and cystocele depend on the presence of anterior, posterior, levator and/or or apical support impairments, as well as the interaction of the prolapse with the opposing compartment.

Is there a correlation between levator ani and urethral sphincter complex status on 3D ultrasonography?

INTRODUCTION AND HYPOTHESIS

To determine the correlation between levator ani deficiency (LAD) and urethral sphincter complex measurements as visualized on 3D endovaginal ultrasonography, and to compare the LAD score with continence status.

METHODS

This was a retrospective analysis of patients seen at our institution between January 2011 and August 2013. Patients were dichotomized into those with urodynamic stress urinary incontinence (SUI) and those with no SUI. Levator ani status was evaluated using a validated scoring system yielding scores of 0 - 6 (normal levator ani/mild LAD), 7 - 12 (moderate LAD), and 13 - 18 (severe LAD). The length, horizontal diameter, and cross-sectional area of the urethra, and the length, width, and the area of the rhabdomyosphincter and smooth muscle sphincter were likewise measured using 3D ultrasound volumes.

RESULTS

Of the 80 patients included, 54 (67.5%) had SUI and 26 (32.5%) were continent. 18 (22.5%) had evidence of mild LAD, 54 (67.5%) had moderate LAD, and 8 (10.0%) had severe LAD. Among patients with SUI, those with normal levator ani muscles or mild LAD had greater urethral smooth muscle width than those with moderate and severe LAD (p = 0.0238). A greater proportion of patients with SUI also had moderate to severe LAD than continent patients (p = 0.0177, OR 3.59, 95% CI 1.21 - 10.65). There was no difference in LAD distribution by type of stress incontinence (presence or absence of intrinsic sphincter deficiency; p =  .2377).

CONCLUSIONS

LAD and urethral sphincter complex status, as visualized on 3D ultrasonography, are independent factors. Moderate to severe LAD is more prevalent in patients with SUI.

[Pelvic floor muscle contraction and maximum urethral closure pressure]

OBJECTIVES

The aim of this study was to precise the relationship between the pelvic floor muscle (PFM) contraction and the maximum urethral closure pressure (MUCP) at rest and during a containing effort.

MATERIALS

Longitudinal study, observational, single-center retrospective performed in successively 358 women addressed for urodynamics. MUCP at rest and during a containing effort, gain of MUCP, functional urethral length (FUL), scores USP and ICQ-SF, cervico-urethral mobility (CUM) according to POP-Q classification and leak point pressure were analyzed according to the PFM contraction.

RESULTS

One hundred and seventy-three had genuine stress urinary incontinence, 25 urge urinary incontinence, 148 mixed incontinence and 12 had no urinary incontinence. PFM contraction was not associated with a hysterectomy, age, parity, BMI, CUM, FUL, MUCP at rest, the severity of the incontinence assessed by ICIQ-SF score and leak point pressure. There was a proportional relationship between PFM contraction and the value of MUCP measured during this contraction (P<0.0001) on the one hand, and the gain of MUCP (P<0.0001) on the other. MUCP at rest was independent from the MUCP during the containing effort and the gain of MUCP.

CONCLUSIONS

The strength of contraction of the PFM is not correlated with MUCP at rest but proportional to the augmentation of the MUCP during the containing effort.

Brain-derived neurotrophic factor in urinary continence and incontinence

Urinary incontinence adversely affects quality of life and results in an increased financial burden for the elderly. Accumulating evidence suggests a connection between neurotrophins, such as brain-derived neurotrophic factor (BDNF), and lower urinary tract function, particularly with regard to normal physiological function and the pathophysiological mechanisms of stress urinary incontinence (SUI) and bladder pain syndrome/interstitial cystitis (BPS/IC). The interaction between BDNF and glutamate receptors affects both bladder and external urethral sphincter function during micturition. Clinical findings indicate reduced BDNF levels in antepartum and postpartum women, potentially correlating with postpartum SUI. Experiments with animal models demonstrate that BDNF is decreased after simulated childbirth injury, thereby impeding the recovery of injured nerves and the restoration of continence. Treatment with exogenous BDNF facilitates neural recovery and the restoration of continence. Serotonin and noradrenaline reuptake inhibitors, used to treat both depression and SUI, result in enhanced BDNF levels. Understanding the neurophysiological roles of BDNF in maintaining normal urinary function and in the pathogenesis of SUI and BPS/IC could lead to future therapies based on these mechanisms.

Fiber type characterization of striated muscles related to micturition in female rabbits

Pelvic and perineal striated muscles are relevant for reproduction and micturition in female mammals. Damage to these muscles is associated with pelvic organ prolapse and stress urinary incontinence. The fiber type composition of skeletal muscle influences the susceptibility for damage and/or regeneration. The aim of the present study was to determine the fiber type composition of a perineal muscle, the bulbospongiosus, and a pelvic muscle, the pubococcygeus. Both muscles were harvested from adult female rabbits (8-10 months old). NADH-TR (nicotinamide adenine dinucleotide tetrazolium reductase) histochemistry was undertaken to identify oxidative and glycolytic muscle fibers. Alkaline (pH 9.4) ATP-ase (actomyosin adenosine triphosphatase) histochemistry was used to classify type I, type IIb or type IIa/IId muscle fibers. Results showed that the content of glycolytic fibers in the bulbospongiosus muscle was higher than that of oxidative fibers. Meanwhile, the opposite was true for the pubococcygeus. In the bulbospongiosus muscle, the content of type IIb muscle fibers was higher than that of type I, but was similar to that of type IIa/IId. In contrast, the content of each fiber type was similar in the pubococcygeus muscle. The relative proportion of fibers in bulbospongiosus and pubococcygeus muscles is consistent with their function during voiding and storage phases of micturition.

Dynamics of male pelvic floor muscle contraction observed with transperineal ultrasound imaging differ between voluntary and evoked coughs

Coughing provokes stress urinary incontinence, and voluntary coughs are employed clinically to assess pelvic floor dysfunction. Understanding urethral dynamics during coughing in men is limited, and it is unclear whether voluntary coughs are an appropriate surrogate for spontaneous coughs. We aimed to investigate the dynamics of urethral motion in continent men during voluntary and evoked coughs. Thirteen men (28-42 years) with no history of urological disorders volunteered to participate. Transperineal ultrasound (US) images were recorded and synchronized with measures of intraabdominal pressure (IAP), airflow, and abdominal/chest wall electromyography during voluntary coughs and coughs evoked by inhalation of nebulized capsaicin. Temporal and spatial aspects of urethral movement induced by contraction of the striated urethral sphincter (SUS), levator ani (LA), and bulbocavernosus (BC) muscles and mechanical aspects of cough generation were investigated. Results showed coughing involved complex urethral dynamics. Urethral motion implied SUS and BC shortening and LA lengthening during preparatory and expulsion phases. Evoked coughs resulted in greater IAP, greater bladder base descent (LA lengthening), and greater midurethral displacement (SUS shortening). The preparatory inspiration cough phase was shorter during evoked coughs, as was the latency between onset of midurethral displacement and expulsion. Maximum midurethral displacement coincided with maximal bladder base descent during voluntary cough, but followed it during evoked cough. The data revealed complex interaction between muscles involved in continence in men. Spatial and temporal differences in urethral dynamics and cough mechanics between cough types suggest that voluntary coughing may not adequately assess capacity of the continence mechanism.

Intra- and interobserver reliability of levator ani muscle biometry and avulsion using three-dimensional endovaginal ultrasonography

OBJECTIVES

To test intra- and interobserver reliability of assessment of levator ani muscle (LAM) biometry and avulsion using antenatal and postnatal three-dimensional (3D) endovaginal ultrasonography (EVUS), and to determine levator-urethra gap (LUG) values on EVUS.

METHODS

Primigravid women were scanned prior to delivery, early postpartum and 3 months postpartum, with EVUS performed at rest using a standardized protocol. During post-processing, measurements were taken in the plane of minimal hiatal dimensions by two independent investigators blinded to the clinical information and each other's results. LAM attachment to the pubic bone was assessed at the pubococcygeus and puborectalis levels using a score system: (1) intact; (2) partial avulsion (< 50%); (3) partial avulsion (≥ 50%); and (4) complete avulsion. Intraclass correlation coefficients (ICCs) and limits of agreement (LOAs) were calculated for each time point, with intraobserver analysis conducted in a random sample of 20 women scanned 3 months following delivery.

RESULTS

One hundred and sixty-nine antenatal scans, 83 early postpartum scans and 75 scans at 3 months postpartum were performed. The intra- and interobserver ICCs, respectively, were 0.95 and 0.86-0.88 for hiatal area, 0.90 and 0.16-0.74 for hiatal transverse diameter, 0.91 and 0.73-0.80 for hiatal anteroposterior diameter, 0.50 and 0.32-0.52 for LAM thickness at the '9 o'clock position' and 0.55 and 0.33-0.45 for LAM thickness at the '3 o'clock position'. Both intra- and interobserver analysis revealed acceptable LOAs for hiatal measurements, but the LOAs were wide for thickness measurements. The correlation of LAM avulsion score was excellent on intra- and interobserver analysis. Antenatal mean ± SD LUGs were 18.8 ± 2.4 mm and 19.2 ± 2.3 mm on right and left sides, respectively; the intraobserver ICC was 0.82-0.91 but LOAs were wide, while interobserver ICC was 0.13-0.68 and also had wide LOAs.

CONCLUSIONS

3D-EVUS is a reliable tool for the assessment of hiatal measurements and LAM avulsion in women during pregnancy and after delivery, but performs less well for measurements of LAM thickness and LUG. EVUS can therefore be used in research studies involving childbirth and recurrent prolapse.

Levator hematoma at the attachment zone as an early marker for levator ani muscle avulsion

OBJECTIVES

Childbirth causes overstretching of the levator ani muscle (LAM), predisposing to avulsion. LAM avulsion has not been evaluated early postpartum using endovaginal ultrasound (EVUS). The aim of this study was to evaluate the relationship between hematomas and LAM avulsion using EVUS and palpation early and late postpartum.

METHODS

Nulliparous women were studied prospectively at 36 weeks' gestation and within 4 days and 3 months postpartum. Palpation and high-frequency three-dimensional EVUS were performed. Two independent investigators reviewed the scans.

RESULTS

No antenatal LAM avulsions were found (n = 269). 114/199 (57.3%) women seen early postpartum agreed to examination. 27/114 (23.7%) had well delineated, hypoechoic areas consistent with hematomas (100% agreement), 26 following vaginal delivery, one following emergency Cesarean section. In total, 38 hematomas were found (11 bilateral, 16 unilateral). Hematomas away from the attachment zone of the LAM to the pubic bone (n = 22) resolved. Hematomas at the attachment zone (n = 16) manifested as pubococcygeus avulsions 3 months postpartum. In addition to these 16 avulsions, we found another 20 at 3 months postpartum. 13/20 were not scanned early postpartum and in seven no hematomas were seen, but avulsion was seen early postpartum. Overall, LAM avulsion was found in 23/191 (12.0%) women (13 bilateral, 10 unilateral) 3 months postpartum. Hematomas were significantly associated with episiotomy, instrumental delivery and increased hiatal measurements. Palpation was unreliable early postpartum as only seven avulsions were diagnosed.

CONCLUSION

Hematomas at the site of LAM attachment to the pubic bone always result in avulsion diagnosed 3 months postpartum. However, one third of avulsions are not preceded by a hematoma at the site of LAM attachment to the pubic bone.

Neuromuscular characterization of the urethra in continent women

OBJECTIVES

: The study's objective was to describe quantitative urethral function parameters in a racially diverse group of continent women.

MATERIALS AND METHODS

: After institutional review board approval, we recruited women without urinary incontinence from the community. To be considered continent, participants answered "never" to the first 6 questions on the stress subscale of the Medical, Epidemiologic, and Social Aspects of Aging urinary incontinence questionnaire. Participants all underwent quantitative concentric urethral electromyography (EMG) and urodynamic testing.

RESULTS

: Thirty-one women with a mean (SD) age of 39 (14) years underwent EMG and urodynamic testing. The cohort was racially diverse with 13 (43%) white women, 13 (43%) African American women, and 4 (14%) Hispanic women. Body mass index (P = 0.12, 0.06), age (P = 0.40, 0.64), and vaginal parity (P = 0.53, 0.76) did not differ by race or ethnicity. We did not detect differences in any EMG parameter by race, ethnicity, or vaginally parity. A mean (range) of 30 (10-55) motor unit action potential (MUP) analyses was identified and analyzed in multiple MUP analysis, and 14 (8-21) were identified and analyzed in interference pattern (IP) analysis. On average, 37% (20%) (mean [SD]) MUPs were polyphasic.Age significantly correlated with several measures of urethral sphincter function. Increasing age was inversely correlated with IP turns (r = -0.57, P = 0.001), IP amplitude (r = -0.43, P = 0.02), IP turns-amplitude ratio (r = -0.54, P = 0.003), and maximum urethral closure pressures (r = -0.41, P = 0.04). Similarly, maximum urethral closure pressures correlated with IP amplitude (r = 0.38, P = 0.04).

CONCLUSIONS

: These urethral neuromuscular function data on the largest cohort of continent women fully characterized with quantitative urethral EMG demonstrate significant neuropathic MUP changes with advancing age.

The role of pelvic and perineal striated muscles in urethral function during micturition in female rabbits

AIM

To evaluate the role of pelvic and perineal striated muscles on urethral function during micturition.

METHODS

Pubococcygeus, or both bulbospongiosus and ischiocavernosus muscles were electrically stimulated during the voiding phase of micturition, and bladder and urethral pressure were simultaneously recorded in urethane anesthetized female rabbits. Bladder and urethral function were assessed measuring urodynamic and urethral pressure variables obtained before and during the stimulation of muscles. Two-tail paired t-tests were carried out in order to determine significant differences (P < 0.05) between groups.

RESULTS

Electric stimulation of the pubococcygeus during voiding decreased voiding efficiency and voided volume, whereas residual volume, the duration of voiding, the interval between bladder contraction and urethral resistance increased. Simultaneously, there was an increase in maximum urethral pressure, as well as an increase in the pressure to return to baseline and in the pressure required to close the urethra. Electrical stimulation of bulbospongiosus and ischiocavernosus muscles increased voiding efficiency, voiding duration, and the maximal pressure in bladder. Meanwhile, the maximal urethral pressure, the time related to the rise of urethral pressure, and the urethral pressure required to close the urethra decreased.

CONCLUSIONS

The stimulation of pelvic and perineal muscles have opposing roles in urethral function during micturition. Pubococcygeus muscles facilitate urethral closure, while they inhibit bladder contraction. In contrast, bulbospongiosus and ischiocavernosus muscles prevent urethral contraction while they promote bladder contraction.

Regenerative medicine as a new therapeutic strategy for lower urinary tract dysfunction

The use of regenerative medicine for the treatment of organic and functional disorders intractable to conventional treatment has increased worldwide. This innovative medical field might particularly hold promise for the treatment of life-threatening diseases or healing of irreplaceable organs, such as the heart, liver and brain. Dysfunction of the urogenital tract and associated organs other than the kidney might not have immediate life-threatening implications; furthermore, the effectiveness of alternative therapy, such as enterocystoplasty for bladder cancer, has been shown. Therefore, most physicians or scientists do not give much importance to these disorders. However, urological disease has increased in developed societies in recent years. Furthermore, medical costs have also escalated. Disorders of the lower urinary tract, such as urinary disturbance or incontinence, can lead to other complications, impairing quality of life and ultimately increasing short- and long-term medical expenses. Regenerative medicine might hold potential solutions to these problems. Recent advances in urogenital regenerative medicine are reviewed in the present article, with particular reference to lower urinary tract reconstruction. The potential of regenerative medicine for the treatment of intractable lower urinary tract dysfunction compared with conventional treatment is also discussed.

Incidental bartholin gland cysts identified on pelvic magnetic resonance imaging

OBJECTIVE

To estimate the prevalence of Bartholin gland cysts in asymptomatic women serving as control participants who underwent pelvic magnetic resonance imaging (MRI) as part of research studies. The secondary aim was to investigate potential demographic characteristics associated with Bartholin gland cysts.

METHODS

Pelvic MRIs from 430 control participants enrolled in five research projects were evaluated. All images were evaluated by at least two authors. The presence, laterality, and size of Bartholin gland cysts were recorded. Demographic information for each participant was obtained at the time of enrollment in the respective parent study.

RESULTS

Approximately 3% of the participants had visible Bartholin gland cysts on MRI scans. Fifty percent of the cysts were identified on the right side, 42.9% were seen on the left side, and 7.1% were bilateral. The cysts were, on average, 1.3×1.2×1.3 cm with dimensions ranging from 0.5 to 2.7 cm. There were no demographic differences between women with and without visible Bartholin gland cysts.

CONCLUSION

Bartholin gland cysts occur in 3% of adult women. The cysts affect women of broad ranges of age and parity. Women with visible Bartholin gland cysts are demographically similar to women without cysts on pelvic imaging.

LEVEL OF EVIDENCE

II.

Phosphodiesterase-5 expression and function in the lower urinary tract: a critical review

Both clinical and preclinical studies have mostly shown beneficial effects for Phosphodiesterase-5 (PDE-5) inhibitors in the treatment of lower urinary tract symptoms. Molecular studies have consistently shown abundant PDE-5 expression in bladder smooth muscle. Data concerning urethral PDE-5 expression have been surprising because striated muscle was not only positively identified, but also found to express more PDE-5 than the smooth muscle. In the prostate, highly variable results have been obtained. For PDE-5 expression, the data have ranged from extremely low to highly abundant. PDE-5 has been found in the glandular epithelium, vascular smooth muscle, endothelium, and fibromuscular stroma.

What causes stress incontinence: Fallacies, fascias and facts

The traditional view of the pathophysiology of stress urinary incontinence (SUI) was that a loss of urethral support was the primary abnormality present. Recent research has challenged this hypothesis, demonstrating that impaired urethral function plays the key causative role. Improving our understanding of the underlying pathologic mechanisms is important to identifying the cause of treatment failures and for developing novel therapies to treat SUI.

Myogenic potential of whole bone marrow mesenchymal stem cells in vitro and in vivo for usage in urinary incontinence

Urinary incontinence, defined as the complaint of any involuntary loss of urine, is a pathological condition, which affects 30% females and 15% males over 60, often following a progressive decrease of rhabdosphincter cells due to increasing age or secondary to damage to the pelvic floor musculature, connective tissue and/or nerves. Recently, stem cell therapy has been proposed as a source for cell replacement and for trophic support to the sphincter. To develop new therapeutic strategies for urinary incontinence, we studied the interaction between mesenchymal stem cells (MSCs) and muscle cells in vitro; thereafter, aiming at a clinical usage, we analyzed the supporting role of MSCs for muscle cells in vitro and in in vivo xenotransplantation. MSCs can express markers of the myogenic cell lineages and give rise, under specific cell culture conditions, to myotube-like structures. Nevertheless, we failed to obtain mixed myotubes both in vitro and in vivo. For in vivo transplantation, we tested a new protocol to collect human MSCs from whole bone marrow, to get larger numbers of cells. MSCs, when transplanted into the pelvic muscles close to the external urethral sphincter, survived for a long time in absence of immunosuppression, and migrated into the muscle among fibers, and towards neuromuscular endplates. Moreover, they showed low levels of cycling cells, and did not infiltrate blood vessels. We never observed formation of cell masses suggestive of tumorigenesis. Those which remained close to the injection site showed an immature phenotype, whereas those in the muscle had more elongated morphologies. Therefore, MSCs are safe and can be easily transplanted without risk of side effects in the pelvic muscles. Further studies are needed to elucidate their integration into muscle fibers, and to promote their muscular transdifferentiation either before or after transplantation.

Role of puborectalis muscle in the genesis of urethral pressure

PURPOSE

The internal (smooth muscle) and the external (rhabdosphincter striated muscle) urethral sphincters have important roles in the genesis of urethral closure pressure. The U-shaped pelvic floor puborectalis muscle is important in the closure of anal and vaginal orifices in humans. We defined the contribution of the puborectalis to urethral pressure.

MATERIALS AND METHODS

A total of 11 female rabbits were anesthetized and prepared to measure urethral, vaginal and anal canal pressure using manometric methods. Pressure was recorded at rest, after administration of pharmacological agents and during electrical stimulation of the puborectalis and rhabdosphincter sphincter muscles. Phenylephrine, sodium nitroprusside (Sigma-Aldrich®) and rocuronium bromide (PharMEDium, Lake Forest, Illinois) were used to define the relative contribution of smooth and striated muscles to urethral pressure. Histology of the pelvic floor hiatus was also studied.

RESULTS

At rest mean ± SEM maximum urethral pressure was 13 ± 6 mm Hg. Sodium nitroprusside (50 μg/kg) infusion resulted in a 30% to 40% decrease in resting urethral pressure (mean 7.2 ± 0.2 mm Hg). Phenylephrine produced a dose dependent increase in urethral pressure (mean 17 ± 6, 25 ± 5 and 29 ± 6 for 5, 10 and 50 μg/kg intravenously, respectively). Electrical stimulation of the puborectalis muscle induced a stimulus dependent increase in urethral, vaginal and anal canal pressure. On the other hand, rhabdosphincter stimulation induced a stimulus intensity dependent increase in urethral pressure only. The increase in urethral pressure after puborectalis muscle stimulation was more than twofold higher than after rhabdosphincter stimulation.

CONCLUSIONS

Our data prove that the puborectalis, a component of the pelvic floor muscles, is an important contributor to urethral pressure in the rabbit.

Novel insight into the dynamics of male pelvic floor contractions through transperineal ultrasound imaging

PURPOSE

Transperineal ultrasound imaging enables the minimally invasive assessment of pelvic floor muscle function. Although commonly used in women, the approach has rarely been reported in men. This approach has advantages because the midsagittal view visualizes a bony landmark and the entire urethral length. This allows investigation of the displacement of multiple points along the urethra and the unique mechanical actions of multiple muscles that could influence continence. We used a new transperineal ultrasound technique to compare the relative displacement of urethrovesical junction, anorectal junction and distal urethra during voluntary pelvic floor muscle contractions in continent men.

MATERIALS AND METHODS

We performed measurement and comparison of urethral displacement at specific urethral regions in 10 continent men (age range 28 to 41 years). Measures made on 2-dimensional midsagittal plane ultrasound images included the displacements of specific points along the urethra. Anatomical considerations suggest that these are caused by contraction of the levator ani, striated urethral sphincter and bulbocavernosus muscles. Pearson's correlation coefficient was used to investigate the relationship between displacements of pairs of points.

RESULTS

Data show individual variation in displacement of the distal urethra (striated urethral sphincter contraction) and urethrovesical junction (levator ani contraction). A strong inverse linear relationship (0.723) between displacements of these points indicates 2 alternative strategies of urethral movement.

CONCLUSIONS

Transperineal ultrasound imaging allows the simultaneous investigation of multiple pelvic floor muscles by measuring urethral displacement. The data provide evidence of different but coordinated strategies of urethral displacement in men.

Reflex contraction of the levator ani in women symptomatic for pelvic floor disorders

OBJECTIVE

Stress urinary incontinence (SUI) is a common health problem in women. Reflex activation of muscular pelvic floor structures may play a role in preserving continence. In this study we aimed to analyze reflex pelvic floor activity on coughing in women seen for urodynamic testing.

METHODS

In a retrospective cohort study we analyzed the data sets of 191 women who attended a tertiary referral service for multichannel urodynamic testing and four-dimensional pelvic floor ultrasound scan between May 2009 and February 2010. Coughs were registered on volume ultrasound at a minimum of 16 Hz and analyzed by postprocessing at a later date, the operator being blinded against all clinical data.

RESULTS

Of 175 analyzable cough volume datasets, a levator reflex was seen in 138 (79%), and clitoral reflex movement in 160 (91%). On multivariable analysis there was a significant relationship between urodynamic stress incontinence (USI) and the absence of a levator reflex (P = 0.045), and a negative relationship with the magnitude of such a reflex (P = 0.046). Reflex timing was not associated with SUI or USI.

CONCLUSION

Reflex contraction of the levator ani can be observed on translabial ultrasound during sudden increases in intra-abdominal pressure. These reflex contractions are common, even in women with symptoms and signs of pelvic floor dysfunction. The observation of a levator reflex on coughing, and its magnitude, show a weak inverse association with the presence of USI.

Bony pelvis dimensions in women with and without stress urinary incontinence

AIMS

To test the null hypothesis that bony pelvis dimensions are similar in women with and without stress urinary incontinence (SUI), both in the postpartum and midlife periods.

METHODS

Secondary analyses were performed of two case-control studies comparing women with SUI to asymptomatic controls. One study examined primiparas in the first 9-12 months postpartum; the other study involved middle-aged women. SUI was confirmed by full-bladder stress test. All subjects underwent pelvic magnetic resonance imaging. The interspinous and intertuberous diameters, subpubic angle, and sacrococcygeal joint-to-the inferior pubic point distance were measured from the images independently by two authors.

RESULTS

In the young cohorts, we compared primiparas with de novo postpartum SUI to both continent primiparas and nulliparas. Postpartum SUI is associated with a wider subpubic angle. There is also a trend towards wider interspinous and intertuberous diameters in the stress-incontinent primiparas as compared to the continent cohorts, although this did not reach statistical significance with our sample sizes. By contrast, no significant differences in bony pelvis dimensions were identified when comparing middle-aged women with SUI and their continent controls.

CONCLUSIONS

Bony pelvis dimensions are different in women with SUI than in matched continent controls. However, these differences are only identified in young primiparas in the postpartum period, not in middle-aged women.

Paraurethral striated muscular structures and pelvic floor muscles contribute to resting urethral closure pressure in rats

INTRODUCTION AND HYPOTHESIS

We investigated physiological functions of the extraordinary muscular structure in the paraurethral area with pelvic floor muscle and the impact of these muscular structures on the resting maximal urethral closure pressure (MUCP) in rats.

METHODS

Sixteen female Wister rats were divided into four groups: Groups I and II rats received 5 and 2.5 IU botulinum toxin A (BoNT-A), respectively, injected into the bilateral paraurethral striated muscles. Group III rats received 2.5 IU BoNT-A injected into the bilateral pelvic floor muscles, and group IV rats received 2.5 IU BoNT-A injected into the unilateral pelvic floor muscles. Measurements of MUCP were made at different time points after BoNT-A injection.

RESULTS

All groups showed a rapid reduction in average MUCP by 70-80 % after BoNT-A injection, regardless of injection site or side.

CONCLUSIONS

Paraurethral striated muscular structures and the pelvic floor muscles possess the function of maintaining resting MUCP in rats.

Urethral distension as a novel method to simulate sphincter insufficiency in the porcine animal model

OBJECTIVES

To describe a novel animal model of intrinsic sphincter deficiency.

METHODS

The study was carried out on 10 female pigs. Injury to the urethral sphincter was induced by distension of the urethra. This was obtained by using the balloon of an 18-F Dufour catheter for 5 min followed by its retraction through the urethra without draining the balloon. The urethral pressure profile was evaluated before injury, immediately postinjury and at day 28 postinjury in the experimental group (n = 5), and on day 1 and day 28 in the control uninjured group (n = 5). The maximal urethral closure pressure, the functional urethral length and the area under curve of the urethral pressure profile were measured.

RESULTS

The mean maximal urethral closure pressure at the beginning of the experiment was 32 cmH(2) O, and the mean functional urethral length was 4.88 cm. The assessment at day 28 showed a reduction of the maximal urethral closure pressure (50% of the control, P > 0.05), the functional urethral length (52.5% of the control, P < 0.05) and the area under curve (52% of the control, P < 0.05) in injured pigs. Histologically, a fibrosis of the sphincter was detected without rupture of the muscle layer in all the samples.

CONCLUSIONS

The proposed porcine model can be used to obtain intrinsic sphincter deficiency-like urodynamic findings without rupturing the sphincter. This methodology can be applied to investigate therapies for intrinsic sphincter deficiency.

Variation of distances from mid-urethra to the obturator foramen: an MRI study

INTRODUCTION AND HYPOTHESIS

To estimate distances from the mid-urethra to the obturator foramina and to explore correlations between pelvic dimensions and body height.

METHODS

This is a secondary analysis of a parent case-control study on the mechanisms of stress urinary incontinence. We measured pelvic dimensions on magnetic resonance images of women with (cases, n = 50) and without (controls, n = 50) stress urinary incontinence.

RESULTS

The mean distance from mid-urethra to the obturator membrane among cases is 31.8 mm (left) and 32.1 mm (right), with a range from 25.9 to 42.0 mm. There were no significant differences in these distances when comparing left with right, or cases with controls. Weak correlation was found between the urethra-to-obturator foramina distances and heights only in the case subjects.

CONCLUSION

There is high variability in the distance from mid-urethra to the obturator foramina. Height should not be used as a predictor of dimensions in the lesser pelvis.

Obstetric levator ani muscle injuries: current status

Levator ani muscle (LAM) injuries occur in 13-36% of women who have a vaginal delivery. Although these injuries were first described using magnetic resonance imaging, three-dimensional transperineal and endovaginal ultrasound has emerged as a more readily available and economic alternative to identify LAM morphology. Injury to the LAM is attributed to vaginal delivery resulting in reduced pelvic floor muscle strength, enlargement of the vaginal hiatus and pelvic organ prolapse. There is inconclusive evidence to support an association between LAM injuries and stress urinary incontinence and there seems to be a trend towards the development of fecal incontinence. Longitudinal studies with long-term follow-up assessing the LAM before and after childbirth are lacking. Furthermore, the consequence of LAM injuries on quality of life due to prolapse and/or urinary and fecal incontinence have not been evaluated using validated questionnaires. Direct comparative studies using the above-mentioned imaging modalities are needed to determine the true gold standard for the diagnosis of LAM injuries. This would enable consistency in definition and classification of LAM injuries. Only then could high-risk groups be identified and preventive strategies implemented in obstetric practice.

Neurophysiology and therapeutic receptor targets for stress urinary incontinence

Stress urinary incontinence is the most common type of urinary incontinence in women. Stress urinary incontinence involves involuntary leakage of urine in response to abdominal pressure caused by activities, such as sneezing and coughing. The condition affects millions of women worldwide, causing physical discomfort as well as social distress and even social isolation. This type of incontinence is often seen in women after middle age and it can be caused by impaired closure mechanisms of the urethra as a result of a weak pelvic floor or poorly supported urethral sphincter (urethral hypermobility) and/or a damaged urethral sphincter system (intrinsic sphincter deficiency). Until recently, stress urinary incontinence has been approached by clinicians as a purely anatomic problem as a result of urethral hypermobility requiring behavioral or surgical therapy. However, intrinsic sphincter deficiency has been reported to be more significantly associated with stress urinary incontinence than urethral hypermobility. Extensive basic and clinical research has enhanced our understanding of the complex neural circuitry regulating normal function of the lower urinary tract, as well as the pathophysiological mechanisms that might underlie the development of stress urinary incontinence and lead to the development of potential novel strategies for pharmacotherapy of stress urinary incontinence. Therapeutic targets include adrenergic and serotonergic receptors in the spinal cord, and adrenergic receptors at the urethral sphincter, which can enhance urethral reflex activity during stress conditions and increase baseline urethral pressure, respectively. This article therefore reviews the recent advances in stress urinary incontinence research and discusses the neurophysiology of urethral continence reflexes, the etiology of stress urinary incontinence and potential targets for pharmacotherapy of stress urinary incontinence.

Effects of prolonged vaginal distension and β-aminopropionitrile on urinary continence and urethral structure

OBJECTIVE

To investigate the effects of prolonged vaginal distension and β-aminopropionitrile (BAPN) on the urinary patterns and urethral structure in female virgin rats.

METHODS

A total of 21 female virgin rats were randomly divided into 3 groups of 7 rats each. The control group received no intervention; the vaginal distension (VD) group was treated with prolonged VD by balloon inflation; and the VD plus BAPN group was treated with VD plus intraperitoneal injection of 150 mg/kg of BAPN every 3 days. Three weeks later, all the rats underwent conscious cystometric analysis and were then killed for histologic analysis of the urethra.

RESULTS

Conscious cystometry identified 0, 3, and 5 rats in the control, VD, and VD plus BAPN groups with an abnormal voiding pattern, respectively. The urethral collagen content was significantly lower in the VD and VD plus BAPN rats compared with the control rats. The urethral elastic fibers were disorganized and shorter in the VD and VD plus BAPN rats and were fragmented and lacking the intermuscle connections in the VD plus BAPN rats. The urethral striated muscle fibers were shorter and more widely spaced in the VD and VD plus BAPN rats than in the control rats. Additionally, those in the VD plus BAPN group exhibited an abnormal wavy shape suggestive of a lack of architectural support.

CONCLUSION

Prolonged vaginal distension caused urodynamic changes and histologic abnormalities in the urethra, including reduced collagen content, fragmented elastic fibers, and sparsely arranged and shortened striated muscle fibers. BAPN appears to interfere with the restoration of collagen and elastic fibers.

Slings in surgery of genuine stress incontinence

PURPOSE

To summarize the available evidence concerning efficacy and safety of standard mid-urethral sling (SMUS) operations for the treatment of stress urinary incontinence (SUI).

METHODS AND RESULTS

A non-systematic literature review was carried out in order to collect the available evidence concerning efficacy and safety of SMUS operations for the treatment of SUI. According to the data of our prior meta-analysis, patients receiving SMUS had significantly higher overall and objective cure rates than those receiving Burch colposuspension, although they had a higher risk of bladder perforations. Patients undergoing SMUS and pubovaginal slings had similar cure rates, although the latter were slightly more likely to experience storage lower urinary tract symptoms and had a higher reoperation rate. Patients treated with retropubic SMUS had slightly higher objective cure rates than those treated with transobturator tape (TOT); however, subjective cure rates were similar, and patients treated with TOT had a much lower risk of some complications. Meta-analysis demonstrated similar outcomes for TOTs. With regard to the novel mini-sling, another meta-analysis from Abdel-fattah et al. demonstrated that repeat continence surgery and de novo urgency incontinence were significantly higher in the patients treated with mini-slings.

CONCLUSION

Patients treated with retropubic tape (RT) experienced slightly higher continence rates than those treated with Burch colposuspension, but they faced a much higher risk of intraoperative complications. RT and pubovaginal slings were similarly effective. The use of RT was followed by objective cure rates slightly higher than TOT and by higher risk of complications. The novel mini-slings do not seem to be more effective than the SMUS.

Mechanisms of continence and surgical cure in female and male SUI: surgical research initiatives

AIMS

To report the conclusions of the Think Tank on mechanisms of incontinence and surgical cure in female and male SUI: surgical research initiatives during the ICI-RS meeting in 2010.

METHODS

The sub-group considered five areas for future research in stress urinary incontinence (SUI); (i) epidemiology and public health efforts in SUI, (ii) the basic sciences examining the physiology and pathophysiology of the continence mechanism, (iii) diagnostic techniques and clinical assessment of SUI, (iv) the future of treatment and surgical cure, and (v) the separate issue of male SUI.

RESULTS

Roadblocks to progress were identified for each of the five directions.

CONCLUSIONS

Future research directions are suggested for each of these areas.

Continent women have better urethral neuromuscular function than those with stress incontinence

INTRODUCTION AND HYPOTHESIS

The objective of this study is to describe urethral neuromuscular function using concentric needle electromyography (EMG) in stress incontinent (SUI) and asymptomatic women.

METHODS

Following Institutional Review Board approval, we recruited SUI and asymptomatic women without urinary incontinence. Participants underwent quantitative urethral EMG and urodynamic testing.

RESULTS

Sixty-seven women (37 SUI, 30 continent) with mean ± SD age of 44 ± 12 years participated. Nearly all EMG parameters showed significant differences between continent and SUI women consistent with better motor unit recruitment in continent women. Continent women had larger-amplitude, longer-duration motor unit action potentials (MUP) with increased turns and better MUP recruitment during bladder filling (P < .05). Increasing age was inversely correlated with nearly all MUP parameters (P < .05), suggesting MUP to be consistent with neuropathy.

CONCLUSIONS

We found significant differences in multiple MUP parameters in urethral sphincter between continent and stress incontinent women, suggesting continent women have better urethral innervation. We also found significant neuropathic MUP changes with advancing age, regardless of continence status.

Comparison of the puborectal muscle on MRI in women with POP and levator ani defects with those with normal support and no defect

INTRODUCTION AND HYPOTHESIS

The objective of this study was to compare puborectal muscle integrity and bulk in women with both major levator ani (LA) defects on MRI and pelvic organ prolapse (POP) to women with normal LA muscle and normal support.

METHODS

This is a case-control study comparing 24 cases with known major LA defects and POP to 24 controls with normal LA and normal support. Axial T-2 weighted MRI scans of the pelvis were evaluated for integrity of the puborectal muscle and degree of muscle bulk.

RESULTS

There were no significant group differences in age, body mass index, vaginal deliveries, or hysterectomy status. In all 48 subjects, the puborectal muscle was visible and had no disruption noted. There was no difference in muscle bulk between groups (control/case, thin 42% vs. 25%, average 42% vs. 38%, thick-17% vs. 38%; P = 0.47).

CONCLUSIONS

Defects and loss of muscle bulk in the puborectal muscle are not seen on MRI in women with major LA defects and POP.