Quantifying bladder outflow obstruction in men: A comparison of four approximation methods exploiting large data samples.

INTRODUCTION: A pressure flow study (PFS), part of the International Continence Society standard urodynamic test, is regarded gold standard for the classification and quantification of the urethral resistance (UR), expressed in the bladder outflow obstruction (BOO). For men with benign prostatic hyperplasia, the minimum urethral opening pressure (pmuo ), found at the end of the passive urethral resistance relation is considered the relevant parameter describing BOO. However, in clinical practice, direct measurements of pmuo are easily confounded by terminal dribbling. For that reason, alternative methods were developed to derive pmuo , and thereby assess BOO using the maximum urine flow rate (Qmax ) and the corresponding pressure (pdetQmax ) instead. These methods were never directly compared against a large data set. With the increasing variety of treatments becoming available more precise grading of UR may become of relevance. The current study compares four well-known methods to approximate pmuo and examines the relation between pmuo and pdetQmax . METHODS: In total, 1717 high-quality PFS of men referred with lower urinary tract symptoms between 2003 and 2020 without earlier lower urinary tract surgery were included. From these recordings, pmuo was calculated according to three one-parameter methods. In addition, a three-parameter method (3PM) was used, based on a fit through the lowest pressure flank of the pressure-flow plot. The estimated pmuo 's were compared with a precisely assessed pmuo . A difference of <10 cmH2 O between an estimate and the actual pmuo was considered accurate. A comparison between the four approximation methods and the actual pmuo was visualized using a Bland-Altman plot. The differences between the actual and the estimated slope were assessed and dependency on pmuo was analyzed. RESULTS: A total of 1717 studies were analyzed. In 55 (3.2%) PFS, 3PM analysis was impossible because all pressures after Qmax were higher than pdetQmax . The 3PM model was superior in predicting pmuo , with 75.9% of the approximations within a range of +10 or -10 cmH2 O of the actual pmuo . Moreover, pmuo according to urethral resistance A (URA) and linearized passive urethral resistance relation (linPURR) appear equally reliable. Bladder outflow obstruction index (BOOI) was significantly less accurate when compared to all others. Bland-Altman analysis showed a tendency of BOOI to overestimate pmuo in men with higher grades of UR, while URA tended to underestimate pmuo in those cases. The slope between pmuo and pdetQmax -Qmax increased with larger pmuo , as opposed to the constant relation proposed within BOOI. Although significant differences were found, the clinical relevance of those differences is not known. CONCLUSION: Of the four methods to estimate pmuo and quantify BOO, 3PM was found the most accurate and BOOI the least accurate. As 3PM is not generally available and performance in lower quality PFS is unknown, linPURR is (for now) the most physiologically accurate.

How should prospective research be designed to legitimately assess the value of urodynamic studies in female urinary incontinence?

AIMS: Since formal evidence demonstrating the value of urodynamic studies (UDS) in functional urology remains elusive, we aimed to consider how best to design robust research for this purpose in female urinary incontinence. METHODS: An expert group was convened to debate the following considerations: (a) precedents for formally proving the value of a gold standard diagnostic test, (b) key research principles, (c) defining a study population, (d) selecting endpoints, (e) defining interventional and controls arms, (f) blinding, (g) powering the study, and (h) duration of follow-up. In each case, we considered the strengths and weaknesses of different approaches in terms of scientific validity, ethical acceptability, practicality, and likelihood of bias. RESULTS: We agreed that unlike evaluating therapies, attempting to judge the value of a diagnostic test based on eventual treatment success is conceptually flawed. Nonetheless, we explored the design of a hypothetical randomized controlled trial for this purpose, agreeing that: (1) the study population must sufficiently reflect its real-world counterpart; (2) clinical endpoints should include not only continence status but also other lower urinary tract symptoms and risks of management; (3) participants in the interventional arm should receive individualized management based on their UDS findings; (4) the most scientifically valid approach to the control arm-empiric treatment-is ethically problematic; (5) sufficient statistical power is imperative; and (6) ≥ 2 years' follow-up is needed to assess the long-term impact of management. CONCLUSIONS: Although a perfect protocol does not exist, we recommend careful consideration of our observations when reflecting on past studies or planning new prospective research.

ICS-SUFU standard: Theory, terms, and recommendations for pressure-flow studies performance, analysis, and reporting. Part 2: Analysis of PFS, reporting, and diagnosis.

AIMS: The Working Group (WG), initiated by the International Continence Society (ICS) Standardisation Steering Committee and supported by the Society of Urodynamics, Female Pelvic Medicine and Urogenital Reconstruction, has revised the ICS Standard for pressure-flow studies of 1997. METHODS: Based on the ICS standard for developing evidence-based standards, the WG developed this new ICS standard in the period from May 2020 to December 2022. A draft was posted on the ICS website in December 2022 to facilitate public discussion and the comments received have been incorporated into this final release. RESULTS: The WG has recommended analysis principles for the diagnosis of voiding dysfunction for adult men and women without relevant neurological abnormalities. New standard terms and parameters for objective and continuous grading of urethral resistance (UR), bladder outflow obstruction (BOO) and detrusor voiding contraction (DVC) are introduced in this part 2 of the standard. The WG has summarized the theory and recommendations for the practice of pressure-flow study (PFS) for patients in part 1. A pressure-flow plot is recommended for the diagnosis of every patient, in addition to time-based graphs. Voided percentage and post void residual volume should always be included in PFS analysis and diagnosis. Only parameters that represent the ratio or subtraction of pressure and synchronous flow are recommended to quantify UR and only parameters that combine pressure and flow in a product or sum are recommended to quantify DVC. The ICS BOO index and the ICS detrusor contraction index are introduced in this part 2 as the standard. The WG has suggested clinical PFS dysfunction classes for male and female patients. A pressure-flow scatter graph including every patient's pdet at maximum flow (pdetQmax ) with maximum flow rate (Qmax ) point should be included in all scientific reports considering voiding dysfunction. CONCLUSION: PFS is the gold standard used to objectively assess voiding function. Quantifying the dysfunction and grading of abnormalities are standardized for adult males and females.

ICS-SUFU standard: Theory, terms, and recommendations for pressure-flow studies performance, analysis, and reporting. Part 1: Background theory and practice.

AIMS: The working group (WG) initiated by the International Continence Society Standardization Steering Committee and supported by the Society of Urodynamics, Female Pelvic Medicine and Urogenital Reconstruction has revised the (1997) ICS Standard for pressure flow studies. METHODS: Based on the ICS standard for developing evidence-based standards, the WG developed this new ICS standard in the period from May 2020 to December 2022. A draft was posted on the ICS website in January 2023 to facilitate public discussion and the comments received have been incorporated into this final release. RESULTS: The WG summarizes the theory and recommends the practice and the terms used for the diagnosis of voiding dysfunction for adult female and male patients without relevant neurological abnormalities, in part 1 of this standard. The WG has also recommended standard principles and parameters for objective and continuous grading of urethral resistance and detrusor voiding contraction on the basis of pressure flow studies in part 2. The recommendations for practice in this part have also the aim to increase the understanding of the physiology as well as the psychology of voiding. The potential effects of the laboratory situation of the test on the voiding as well as the role of the urodynamicist in this regard are discussed. The WG has recommended to use for diagnosis only the voidings that are considered representative by the patient. CONCLUSION: A pressure flow study is the gold standard to assess voiding function and to quantify dysfunction. This part of the standard explains the clinical background, gives recommendations for the execution of a pressure flow study and lists relevant terms, parameters, and units of measurements.

Acceptability and perceived value of urodynamics from the patient perspective: A narrative review.

BACKGROUND: The value and application of urodynamic evaluation (UDS) have been a controversial topic in recent years. Gaining robust data on the patient viewpoint in this area is important since, even when UDS findings do not change the management plan, the objective diagnostic information gained from UDS may be valued by patients. Moreover, insights from UDS may empower treating physicians to counsel patients more effectively and manage their expectations regarding treatment outcomes. OBJECTIVE: This expert narrative review aims to analyze the findings of published studies in this area, looking at two topics in turn: (a) the tolerability and acceptability of the UDS procedure itself from the patient perspective and (b) patient perceptions of the clinical value of insights provided by UDS. DESIGN, SETTING, PARTICIPANTS, AND OUTCOME MEASUREMENTS: An evidence assessment was conducted using selected articles from the literature reporting data on patients' perspectives on the tolerability, acceptability, utility, and value of the urodynamic investigation. RESULTS AND LIMITATIONS: Although pain, discomfort, and infection risks are frequently used as a rationale to skip UDS when initial management fails, there is good evidence that, from the patients' perspective, the procedure is very well tolerated in most cases. There are only a few articles available that assess patient perceptions of the usefulness of UDS, but those that do exist appear to demonstrate that the insights gained from UDS are widely welcomed by patients in the interest of receiving a more tailored and personalized treatment approach. CONCLUSION: From the patient perspective, UDS appears to be a well-accepted and well-tolerated diagnostic tool in patients with lower urinary tract symptoms, particularly when an appropriate explanation is provided before the examination. Our review also highlights that patients value the objective information provided by UDS and that this outweighs the temporary invasiveness of the test. This information is particularly relevant in light of the relative lack of evidence in the literature about patient expectations of specialist care in functional urology, which may have hindered progress with quality of care.

Sensations Reported During Urodynamic Bladder Filling in Spinal Cord Injury Patients Give Additional Important Information.

PURPOSE: This study investigated the sensations reported during filling cystometry in patients with spinal cord lesions (SCLs) of different levels and completeness. METHODS: In this retrospective cohort study, information was gathered on patients' age and sex, cause of SCL, American Spinal Injury Association Impairment Scale (AIS), and lower urinary tract-related sensations in daily life. Filling cystometry (videourodynamics) was performed following the International Continence Society Good Urodynamic Practice Guidelines. In addition to bladder filling sensations (first sensation of bladder filling, first desire to void, strong desire to void), other sensations, such as detrusor overactivity related sensation and pain, were noted. RESULTS: In total, 170 patients were included (age, 45±17 years; 114 males and 56 females, 92 with complete and 78 with incomplete SCL). The test was done 6±4 years post-SCL. Sensation was reported by 57% of all patients. Half of the patients with complete SCL (46 of 92) had sensation, while 36% of those with incomplete SCL (28 of 78) reported no sensation. Bladder awareness was not predictable by the AIS. The filling sensations reported were equivalent to those given in the terminology of ICS. Pain was seldom present (6%, 10 of 170), and detrusor overactivity contraction was felt by 45 of 78 (58%). Very few patients used sensory information for bladder management at home. CONCLUSION: After SCL, most patients retained the ability to be aware of the lower urinary tract, and were assessable and gradable during urodynamic testing. The filling sensations were not different from those described in healthy individuals, but the number and sequence of the sensations were altered in a minority of patients. Pain and a sensation of unstable contractions gave additional important information. As different sensations relate to different spinal afferent pathways, the sensory evaluation during cystometry provided additional important information on the spinal cord's condition.

Head-to-head comparison of pressures during full cystometry, with clinical as well as in-depth signal-analysis, of air-filled catheters versus the ICS-standard water-filled catheters.

AIMS: To compare in vivo differences of two catheter systems for urodynamics to further discover their measurement properties. METHODS: Side-by-side catheterization with two catheters for intravesical and abdominal pressure during full cystometry in 36 prospectively recruited patients with analysis of mean and absolute differences at urodynamic events and post hoc in-depth signal analysis comparing the full pressure traces of both systems. RESULTS: The mean pressure differences at urodynamic events between air-filled and water-filled systems are small, however, with a large variation, without a systematic difference. The majority of the intersystem differences are significantly larger than 5 cmH2 O. Further analysis showed that urodynamic event pressure differences of both systems at the start of the test were carried forward throughout the remainder of the test without subsequent or additional tendency to differ. Post hoc whole test signal analysis with pressures equalized from the first sample shows high cross-correlation (>0.981) between the pressure signals per location (rectum and bladder) per test and almost zero-time shift (<0.05 s) of all cystometry pressure samples. CONCLUSIONS: We confirm earlier studies that showed random differences at events between air-filled and water-filled pressures during clinical urodynamic testing and confirm that these are intrinsic but not systematic-and still incompletely explained-offset-baseline differences. We determined on closer full measurement analysis after equalizing, that both systems are similar in displaying urodynamic pressure variations and amplitudes. We also confirm that both systems require awareness of intrinsic measurement properties during urodynamic testing and especially may necessitate adjustment of pressure offsets into a quantitative diagnosis of a urodynamic test.

International Urogynecology Consultation Chapter 1 Committee 5: relationship of pelvic organ prolapse to associated pelvic floor dysfunction symptoms: lower urinary tract, bowel, sexual dysfunction and abdominopelvic pain.

INTRODUCTION AND HYPOTHESIS: This article from Chapter 1 of the International Urogynecology Consultation (IUC) on Pelvic Organ Prolapse (POP) establishes the prevalence of lower urinary tract disorders, bowel symptoms, vulvo-vaginal/lower abdominal/back pain and sexual dysfunction in women with POP. METHODS: An international group of nine urogynecologists/urologists and one medical student performed a search of the literature using pre-specified search terms in Ovid, MEDLINE, Embase and CINAHL from January 2000 to March 2019. Publications were eliminated if not relevant or they did not include clear definitions of POP or the symptoms associated with POP. Definitions of POP needed to include both a physical examination finding using a validated examination technique and the complaint of a bothersome vaginal bulge. Symptoms were categorized into symptom groups for ease of evaluation. The Specialist Unit for Review Evidence (SURE) was used to evaluate for quality of the included articles. The resulting list of articles was used to determine the prevalence of various symptoms in women with POP. Cohort studies were used to evaluate for possible causation of POP as either causing or worsening the symptom category. RESULTS: The original search yielded over 12,000 references, of which 50 were used. More than 50% of women with POP report lower urinary tract symptoms. Cohort studies suggest that women with POP have more obstructive lower urinary tract symptoms than women without POP. Pain described in various ways is frequently reported in women with POP, with low back pain being the most common pain symptom reported in 45% of women with POP. In cohort studies those with POP had more pain complaints than those without POP. Sexual dysfunction is reported by over half of women with POP and obstructed intercourse in 37-100% of women with POP. Approximately 40% of women have complaints of bowel symptoms. There was no difference in the median prevalence of bowel symptoms in those with and without POP in cohort studies. CONCLUSIONS: The prevalence of lower urinary tract disorders, bowel symptoms, vulvo-vaginal/lower abdominal/back pain and sexual dysfunction in women with POP are common but inconsistently reported. There are few data on incidence of associated symptoms with POP, and cohort studies evaluating causality are rare or inconsistent. Obstructive voiding, lower abdominal and pelvic pain, and sexual dysfunction are most frequently associated with POP.

Good urodynamic practice: Pressure signal quality immediately after catheter insertion for cystometry with a water-filled pressure transducer system and its relevance for the ICS zero procedure.

AIM: This study aims to evaluate the intracorporeal pressures immediately after the insertion of the catheters for urodynamic testing with a water-filled urodynamic pressure transducer system to determine the relevance of the International Continence Society (ICS) zeroing principles. METHODS: Here, a retrospective analysis of a random series of urodynamic recordings is performed. The initial pressures, immediately after the insertion of the catheters, have been compared with the pressures after some milliliters of filling and flushing away of the gel, used with insertion, and/or the mucus and debris from the inserted catheters. Differences of initially recorded intravesical and intrarectal pressures from those after flushing and filling are analyzed and associated with the ICS standard practice of zeroing. RESULTS: Statistically and clinically significant differences between the initial pressures and the pressures after filling and flushing are observed, with nonphysiological initial pressures in 62% of the studies. Some filling (20 ml or more in the bladder) and flushing of the pressure channels resulted in the registration of physiological pressures and synchronous response from both lines on abdominal pressure increases. CONCLUSIONS: The pressure signal quality of a water-filled urodynamic system immediately after catheter insertion is low with inaccurately displayed pressure values, but it changes to normal after flushing the pressure channels and some filling. Rezeroing of the intracorporeal pressures immediately after catheter insertion for cystometry is the inappropriate correction procedure that misleadingly modifies the false initial pressures, resulting in ongoing unrealistic urodynamic study pressures.

What developments are needed to achieve less-invasive urodynamics? ICI-RS 2019.

AIMS: To assess the state of technologies for urodynamics that are less invasive than standard cystometry and pressure-flow studies and to suggest areas needing research to improve this. METHODS: A summary of a Think Tank debate held at the 2019 meeting of the International Consultation on Incontinence Research Society is provided, with subsequent analysis by the authors. Less-invasive techniques were summarized, classified by method, and possible developments considered. Discussions and recommendations were summarized by the co-chairs and edited into the form of this paper by all authors. RESULTS: There is a full spectrum of technologies available for less-invasive assessment, ranging from simple uroflowmetry through imaging techniques to emerging complex technologies. Less-invasive diagnostics will not necessarily need to replace diagnosis by, or even provide the same level of diagnostic accuracy as, invasive urodynamics. Rather than aiming for a technique that is merely less invasive, the priority is to develop methods that are either as accurate as current invasive methods, or spare patients from the necessity of invasive methods by improving early triaging. CONCLUSIONS: Technologies offering less-invasive urodynamic measurement of specific elements of function can be potentially beneficial. Less-invasive techniques may sometimes be useful as an adjunct to invasive urodynamics. The potential for current less-invasive tests to completely replace invasive urodynamic testing is considered, however, to be low. Less-invasive techniques must, therefore, be tested as screening/triaging tools, with the aim to spare some patients from invasive urodynamics early in the treatment pathway.

International Consultation on Incontinence 2016; Executive summary: Urodynamic testing.

AIMS: The International Consultation on Incontinence has published an update of the recommendations for the diagnosis and management of urine incontinence (ICI2016). This manuscript summarizes the consultations committee-recommendations with regard to urodynamic assessment. METHODS: Expert consensus on the basis of structured evidence assessment has been the basis of the consultations publication and has been summarized by the committee for this manuscript. RESULTS: Patients that are not satisfied with their initial management on the basis of their reported signs and symptoms of urinary incontinence, as well as all patients with neurological abnormalities that are potentially relevant for the function of the lower urinary tract, may very likely profit from objective diagnosis and staging and grading of their dysfunction, with urodynamic testing, regardless their age, vulnerability and/or comorbidities. The principles and technical innovations as well as the principal recommendations for the utilization of (invasive) urodynamic assessment for women, men, children, and vulnerable elderly, with or without neurogenic lower urinary tract dysfunction with urinary incontinence are provided in this abbreviated ICI recommendations-document. CONCLUSIONS: The ICI2016 committee on urodynamics presents an executive summary of the most important reasons and recommendations for the use of urodynamic investigations for patients with urinary incontinence.

Clinical Epidemiology: Detrusor Voiding Contraction Maximum Power, Related to Ageing.

OBJECTIVE: To report clinical epidemiology of detrusor (bladder) muscle contraction maximum related to ageing in patients referred with signs and symptoms of lower urinary tract dysfunction. STUDY DESIGN AND SETTING: One thousand three hundred and eight urodynamic pressure-flow measurements were analyzed in retrospective. Standard measures of detrusor muscle voiding contraction strength were compared for gender and ranked by age (range 20-90 years). RESULTS: A decline in maximum detrusor contraction strength was observed when the results were ranked according to age. Detrusor muscle maximum voiding contraction was on average 30% less powerful in older women and 12% less powerful in the aged men, when compared to the younger. This is transversal data-interpreted in a longitudinal manner-and from persons referred to specialist care with (the full spectrum of) signs and symptoms of lower urinary tract dysfunction. Therefore these results are relevant for clinical epidemiology but not definitely generalizable to (symptom-free) population level. CONCLUSIONS: Clinical epidemiologic evaluation of patients referred with lower urinary tract symptoms, found lower detrusor maximum contraction strength in higher-age cohorts, both for women as for men. The maximum detrusor strength difference in association with age was larger in women than in men.

ICS educational module: Cystometry in children.

AIMS: To introduce the standard procedure of cystometry and interpretation of the results in children. METHODS: The literature on cystometry in children in PubMed for the last 20 years was reviewed. The updated knowledge regarding indication, preparation, technique, and interpretation of cystometry in children were summarized. RESULTS: Filling cystometry is the core content of a paediatric urodynamic study. In this section, the technique for performing cystometry is introduced in details. Emphasis is placed on correctly setting up the equipment according to ICS and ICCS guidelines, using appropriate terminology, providing indications for its performance with specific considerations for children, and proper interpretation of results. CONCLUSIONS: Cystometry can be used in children including newborn to evaluate lower urinary tract dysfunction.

What research is needed to validate new urodynamic methods? ICI-RS2017.

AIMS: In recent years urodynamic innovations, although well researched, have failed to follow a standardized development pathway specifically in terms of clinical trials undertaken to demonstrate efficacy. This was discussed at the International Consultation on Incontinence Research Society (ICI-RS) in Bristol, United Kingdom, 2017 with the aim of defining minimum standards for future urodynamic research. METHODS: The recent recommendations from the IDEAL (innovation, development, exploration, assessment, and long-term study) collaboration regarding surgical research were reviewed. Two examples of recent novel urodynamic technologies, the penile cuff test and air charged urodynamic catheters were used as case studies and the research programmes behind their development were critiqued. RESULTS: The rigorous and standardized model of surgical research proposed by the IDEAL collaboration was endorsed as an appropriate model for future urodynamic research. A methodical approach to research can fulfil a host of objectives including illustration of the clinical need, help with design and refinement of technique and proving efficacy for any new test or device. The penile cuff test is a novel urodynamic measurement technique that has been well researched and is now used in clinical practice. Further research is needed before air charged catheters can be recommended for widespread clinical use and the IDEAL framework provides a template for ongoing development. CONCLUSIONS: In the future, these recommendations should lead to a more standardized and uniform programme of urodynamic research and enable a thorough evaluation of new technologies prior to wider clinical uptake.

ICS educational module: Pressure flow study in children.

AIMS: To introduce the standard procedure and results interpretation of pressure/flow study (PFS) in children. METHODS: The literature on PFS in children in PubMed for the last 20 years was reviewed. The updated knowledge on PFS in children in children regarding indication, preparation, technique, and interpretation were summarized. RESULTS: This educational module explains when and how to do a PFS and how to analyze the results. All requirements and instructions for the PFS in children described in this document follow ICS reports on Good Urodynamic Practice and urodynamic equipment performance as well as guidelines from the ICCS. PFS can be obtained subsequent to filling cystometry with no specific additional equipment (apart from a flowmeter) or patient preparation needed. It requires both vesical and intra-abdominal pressures being recorded. Information from clinical history, physical examination, voiding diaries, and free uroflowmetry with or without perineal patch EMG and pertinent imaging results should be available before undertaking urodynamic testing. CONCLUSIONS: Following ICS and ICCS guidelines, PFS is an easy procedure and a useful tool to provide information on voiding function in children.