Diagnostic Tests for Female Bladder Outlet Obstruction: A Systematic Review from the European Association of Urology Non-neurogenic Female LUTS Guidelines Panel

A novel predictive model for noninvasively diagnosing bladder outlet obstruction in female patients based on clinical features and uroflowmetry parameters

OBJECTIVE

To develop and validate a simple prediction model to diagnose female bladder outlet obstruction (fBOO) because of the invasive nature of standard urodynamic studies (UDS) for diagnosing fBOO.

METHODS

We retrospectively analyzed the data of 728 women who underwent UDS at Tongji Hospital between 2011 and 2021. The definition of fBOO was Pdet.Qmax  - 2.2 × Qmax  > 5 (BOOIf > 5). Independent predictive factors of fBOO were determined by multivariable logistic regression analysis. These predictive factors were incorporated into a predictive model to assess the risk of fBOO.

RESULTS

Of the 728 patients, 249 (34.2%) were identified as having fBOO and these women were randomly assigned to two groups, a model development group and a model validation group. Multivariate logistic regression demonstrated that age, Qmax , flow time, and voiding efficiency were independent risk factors for fBOO. The predictive model of fBOO showed a satisfactory performance, with area under the curve being 0.811 (95% confidence interval [CI] 0.771-0.850, P < 0.001), which was confirmed to be 0.820 (95% CI 0.759-0.882, P < 0.001) with external validation. The calibration curve indicated that the predicted probability had an excellent correspondence to observed frequency. Decision curve analysis demonstrated a greater clinical net benefit compared with the strategies of treat all or treat none when the predicted risk was in a range of 3% and 75%.

CONCLUSION

A novel predictive model of fBOO was developed and validated based on clinical features and noninvasive test parameters in female patients with lower urinary tract symptoms. The model is a quick and easy-to-use tool to assess the risk of fBOO for urologists in their routine practice without an invasive UDS.

Bladder outlet obstruction in women: Advanced evaluation

INTRODUCTION

Herein, we provide a review of the indications, practical considerations, and interpretation of urodynamics (UDS) with or without fluoroscopy, as well as cystourethroscopy, for women with suspected bladder outlet obstruction (BOO).

METHODS AND RESULTS

A narrative review was performed focusing on the current primary literature and society guidelines around advanced diagnostic modalities for female BOO patients. UDS studies help diagnose BOO by identifying high-pressure low-flow voiding patterns and/or the characteristic radiographic appearance of the bladder neck and urethra during micturition. Cystourethroscopy aids in evaluating structural aberrations of the bladder outlet, and in surgical planning.

CONCLUSIONS

UDS studies and cystourethroscopy are useful adjuncts in carefully-selected female patients with suspected BOO.

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.

[Interobserver agreement in the diagnosis of bladder outlet obstruction in women]

Background

The diagnosis of bladder outlet obstruction (BOO) in women is a challenge for functional urology. In Mexico there are few data that report the prevalence of OTSV in women, being up to 24% in a group of patients.

Objective

The aim of this study is to compare six different definitions of bladder outlet obstruction and evaluate the interobserver agreement in an educational setting.

Material and Methods

Urodynamic studies (UDS) of women with and without diagnosis of BOO were retrospectively assesed. Farrar, Chassagne, Lemack, Defreitas, Blavais and Groutz, Solomon-Greenwell definitions were evaluated. All UDS were independently reviewed by 5 observers. The easiest, the hardest and the fastest were chosen. Interobserver agreement to classify the patients as obstructed was assessed by kappa reliability statistical analysis. We classified the type of mistakes the participants made; error of interpretation and miscalculation.

Results

A total of 28 urodynamic studies were reviewed. All observers had a substantial agreement (0.64-0.78) to classify BOO using all but Lemack and Solomon-Greenwell definitions. A total 120 errors from 840 responses were found; 45.8% errors of interpretation of UDS and 54.1% miscalculation of the equation. Finally, all the participants chose the Solomon-Greenwell was the most difficult definition.

Conclusion

Chassagne, Defreitas and Farrar definitions proved substantial interobserver agreement. Solomon-Greenwell and Lemack´s definitions had the highest number of pitfalls and the lowest level of agreement.

Systematic review of urinary biomarkers of female bladder outlet obstruction (fBOO)

Objective: Diagnosis of bladder outlet obstruction (BOO) in females is often challenging, not only because of the overlap in storage and voiding symptoms in women with various etiologies of lower urinary tract (LUT) dysfunction but also due to the lack of standardized urodynamic criteria to define the condition. There is an unmet need of biologic markers to evaluate BOO in females as an adjunct to other clinical criteria. We sought to elucidate the role of urinary biomarkers in female BOO. Material and methods: We performed a systematic review of studies involving urinary biomarkers in female BOO. The search was performed in PubMed. A total of 58 papers were retrieved and 2 were included for final analysis.Results: Currently, there are no validated biologic markers for female BOO available. Having a biomarker that can be obtained through a urine sample will be an invaluable tool to evaluate and counsel patients with LUT symptoms and possible BOO. The use of NGF as an indicator of BOO in female patients seems to be promising: NGF levels are elevated in women with BOO when compared with normal controls. Conclusions: We found that NGF levels may be applied as a useful biomarker in the diagnosis and evaluation of female patients with BOO symptoms. It will not completely replace other clinical diagnostic tools such as formal urodynamic testing but play a role as a supplement to it. Nevertheless, further studies should be conducted to establish NGF levels as a female BOO biomarker and a routine testing modality.