Urethral Pressure Variation: A neglected contributing factor in patients with overactive bladder syndrome?

How Does the Urethra Respond to Bladder Filling in Continent and Incontinent Women?

OBJECTIVE

The objective of this study was to describe mean urethral pressure (MUP) during filling cystometry in continent and incontinent women.

METHODS

Incontinent women were recruited from a urogynecology clinic if they answered "sometimes" or "always" to 1 of the items on the Medical, Epidemiologic, and Social Aspects of Aging questionnaire. Participants were categorized by Medical, Epidemiologic, and Social Aspects of Aging scores into stress urinary incontinence (SUI) or urgency urinary incontinence (UUI) groups. Continent women were recruited from the community. Multichannel urodynamics were performed using microtip catheters. Urethral pressure profiles were obtained with an empty bladder and at 100-mL increments during filling. Data were analyzed in SPSS. Continuous variables were compared with independent t test or analysis of variance, categorical variables with the χ2 test, and multivariable comparisons were made with linear regression.

RESULTS

Eighty-six women (30 continent, 56 incontinent: 37 SUI, 19 UUI) with a mean ± SD age of 48 ± 15 years and a body mass index (BMI) of 31 ± 9 participated. Sixty-nine percent were White, 43% were postmenopausal, and 80% were parous. Continent women were younger (P < 0.001) and had a lower BMI (P = 0.004). Mean cystometric capacity was higher in women with SUI and continent women than in women with UUI (430 ± 142, 448 ± 101, and 332 ± 160, P = 0.04). Continent women had higher MUP at baseline when controlling for age, BMI, and parity (84 ± 35 cmH2O vs 62 ± 28 cmH2O; aR2 = 0.2, P = 0.02) compared with incontinent women. During filling, MUP in continent women was 20-30 cmH2O higher at all bladder volumes than incontinent women. Mean urethral pressure increased significantly between baseline and 300 mL in continent women (P < 0.005) and women with SUI (P = 0.04), but not in women with UUI (P = 0.48).

CONCLUSIONS

Continent women have greater baseline MUP and greater increases in MUP during bladder filling than incontinent women.

Exploratory analysis of the effect of mirabegron on urodynamic sensation parameters and urethral pressure variations

INTRODUCTION AND HYPOTHESIS

Urethral instability (URI) has in the past been defined by the International Continence Society (ICS), but was excluded from ICS terminology and definitions shortly after because of a lack of consensus about the clinical importance of this phenomenon. Recently, interest in URI and its possible role in overactive bladder (OAB) increased again. In the last decade, a beta 3 adrenoreceptor agonist (mirabegron) was approved for the treatment of OAB. The effect of mirabegron on urethral pressure during filling cystometry is unknown. The aim of this study was to assess the influence of mirabegron on urethral pressure variations during urodynamic investigation and the association of symptoms and voiding diary data before and during treatment.

METHODS

This prospective study included 51 consecutive adult female patients, referred with OAB. Patients were evaluated using a voiding diary, two validated questionnaires and two urodynamic investigations, one before and one after 6 weeks of treatment with mirabegron. URI was defined as an urethral pressure drop exceeding 30 cmH₂O during filling cystometry.

RESULTS

The prevalence of URI was 31% at initial urodynamic investigation, and 19% at second investigation. URI is more common than DO with 18% prevalence at initial evaluation. Treatment with mirabegron resulted in significant changes in symptoms and urodynamic sensory markers in patients with URI.

CONCLUSION

Urethral pressure variations are significantly reduced by treatment with mirabegron in patients with URI. URI seems to have a predictive value in treatment choices for OAB. Future research should elucidate this.

Are there different patterns of detrusor overactivity which are clinically relevant? ICI-RS 2018

INTRODUCTION

Different patterns of detrusor overactivity (DO) have been described and included in several standardization terminology documents. However, it is unclear if these different patterns have any clinical significance.

METHODS

This is a report of the proceedings of Proposal 3: "Are there different patterns of detrusor overactivity which are clinically relevant?" from the annual International Consultation on Incontinence-Research Society (ICIRS) meeting, which took place from 14 to 16 June 2018, in Bristol, UK.

RESULTS

We have collected and discussed, as a committee, the evidence about different urodynamic (UD) patterns of detrusor overactivity and their potential clinical significance. We reviewed the important previous basic research and clinical studies and compiled summaries. The discussion focused on clinical relevance of different UD patterns of DO and what further research is required.

CONCLUSIONS

There are several UD definitions of patterns of detrusor overactivity, however the clinical relevance of these definitions remains unclear. Future research should concentrate on defining the pattern of DO in relation to clinical diagnosis, gender, age, and treatment outcomes.

Urodynamic performance in boys with Y-type urethral duplication

PURPOSE

The aim of this study was to elucidate the urodynamic features of patients with Y-type urethral duplication.

METHODS

Patients with Y-type urethral duplication were retrospectively analyzed. Clinical presentation, urodynamic findings, surgical methods, and treatment outcomes were reviewed.

RESULTS

From 2014 to 2016, six boys were diagnosed with Y-type urethral duplication at our institution. All patients underwent urodynamic testing. Urodynamic testing in patient 1 and 2 revealed detrusor pressure as 100cmH2O and 88cmH2O in the voiding stage, while urinary flow rate were 0ml/s and 2.8ml/s with volume of residual urine as 300ml and 110ml respectively, which consistent with the typical urodynamic of lower urinary tract obstruction. Patient 1, 3, 4 and 6 showed impaired bladder compliance as 7.5ml/H2O, 12ml/H2O, 6ml/H2O and 6ml/H2O respectively. Patient 5 and 6 also showed maximum urethral pressure as 110cmH2O and 125cmH2O with maximum urethral closure pressure as 103cmH2O and 110cmH2O respectively in the resting state.

CONCLUSIONS

Y-type urethral duplication is one potential cause of lower urinary tract obstruction, as seen in the abnormal urodynamic findings in our patients. Further studies are needed to elucidate the characteristics of this rare condition and determine optimal surgical management.

TYPE OF STUDY

Retrospective case series.

LEVEL OF EVIDENCE

Level 4 observational study without controls.

What are the origins and relevance of spontaneous bladder contractions? ICI-RS 2017

INTRODUCTION

Storage phase bladder activity is a counter-intuitive observation of spontaneous contractions. They are potentially an intrinsic feature of the smooth muscle, but interstitial cells in the mucosa and the detrusor itself, as well as other muscular elements in the mucosa may substantially influence them. They are identified in several models explaining lower urinary tract dysfunction.

METHODS

A consensus meeting at the International Consultation on Incontinence Research Society (ICI-RS) 2017 congress considered the origins and relevance of spontaneous bladder contractions by debating which cell type(s) modulate bladder spontaneous activity, whether the methodologies are sufficiently robust, and implications for healthy and abnormal lower urinary tract function.

RESULTS

The identified research priorities reflect a wide range of unknown aspects. Cellular contributions to spontaneous contractions in detrusor smooth muscle are still uncertain. Accordingly, insight into the cellular physiology of the bladder wall, particularly smooth muscle cells, interstitial cells, and urothelium, remains important. Upstream influences, such as innervation, endocrine, and paracrine factors, are particularly important. The cellular interactions represent the key understanding to derive the integrative physiology of organ function, notably the nature of signalling between mucosa and detrusor layers. Indeed, it is still not clear to what extent spontaneous contractions generated in isolated preparations mirror their normal and pathological counterparts in the intact bladder. Improved models of how spontaneous contractions influence pressure generation and sensory nerve function are also needed.

CONCLUSIONS

Deriving approaches to robust evaluation of spontaneous contractions and their influences for experimental and clinical use could yield considerable progress in functional urology.