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Urethral support in female urinary continence part 1: dynamic measurements of urethral shape and motion

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Abstract

Introduction and hypothesis

Urethral closure mechanism dysfunction in female stress urinary incontinence (SUI) is poorly understood. We aimed to quantify these mechanisms through changes in urethral shape and position during squeeze (voluntary closure) and Valsalva (passive closure) via endovaginal ultrasound in women with varying SUI severity.

Methods

In this prospective cohort study, 76 women who presented to our tertiary center for urodynamic testing as preoperative assessment were recruited. Urodynamics were performed according to International Continence Society criteria. Urethral pressures were obtained during serial Valsalva maneuvers. Urethral lengths, thicknesses, and angles were measured in the midsagittal plane via dynamic anterior compartment ultrasound. Statistical shape modeling was carried out by a principal component analysis on aligned urethra shapes.

Results

Age, parity, and BMI did not vary by SUI group. Ultrasound detected a larger retropubic angle, urethral knee-pubic bone angle (a novel measure developed for this study), and infrapubic urethral length measurements at Valsalva in women with severe SUI (p = 0.016, 0.015, and 0.010). Shape analysis defined increased “c” shape concavity and distal wall pinching during squeeze and increased “s” shape concavity and distal wall thickening during Valsalva (p < 0.001). It also described significant urethral shape differences across SUI severity groups (p < 0.001).

Conclusions

Dynamic endovaginal ultrasound can visualize and allow for quantification of voluntary and passive urethral closure and variations with SUI severity. In women with severe SUI, excessive bladder neck and distal urethra swinging during Valsalva longitudinally compressed the urethra, resulting in a proportionally thicker wall at the mid-urethra and urethral knee.

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Abbreviations

PCA:

principal component analysis

ROC:

receiver-operating characteristic

SUI:

stress urinary incontinence

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Funding

This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant no. 1747452. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Author information

Authors and Affiliations

  1. Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA

    Megan R. Routzong & Steven D. Abramowitch

  2. Statistician, NorthShore University HealthSystem Research Institute, Evanston, IL, USA

    Cecilia Chang

  3. Female Pelvic Medicine and Reconstructive Surgery (FPMRS), Division of Urogynecology, University of Chicago Pritzker School of Medicine, NorthShore University HealthSystem, 9650 Gross Point Road, Suite 3900, Skokie, IL, 60076, USA

    Roger P. Goldberg & Ghazaleh Rostaminia

Authors
  1. Megan R. Routzong
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  2. Cecilia Chang
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  5. Ghazaleh Rostaminia
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Contributions

Routzong: data analysis, manuscript writing

Chang: data analysis, manuscript editing

Goldberg: project development, manuscript editing

Abramowitch: project development, data analysis, manuscript editing

Rostaminia: protocol/project development, data collection, data analysis, manuscript writing

Corresponding author

Correspondence to Ghazaleh Rostaminia.

Ethics declarations

Financial disclaimers/conflict of interest

Routzong was funded by NSF GRFP Grant #1747452.

Chang has nothing to disclose.

Goldberg has nothing to disclose.

Abramowitch receives investigator-initiated research funding from Renovia Inc. for work unrelated to this study.

Rostaminia has nothing to disclose.

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Supplementary Information

Supplementary Table 1

Patient demographics, symptoms, and POP-Q measures across SUI groups (DOCX 18 kb)

Supplementary Table 2

Urodynamics (DOCX 19 kb)

Supplementary Table 3

Multinomial logistic regression for predictors of the presence of SUI symptoms (with categorical variables) with no SUI as the reference (DOCX 15 kb)

Supplementary Table 4

Univariate ANOVA (evaluating the significance of maneuver and SUI severity) and post-hoc comparisons (evaluating the differences between no, mild, and severe SUI) of the PC scores of significant modes of variation from the statistical shape model. To be considered significant, p-values had to be greater than corresponding Benjamini-Hochberg critical values (DOCX 17 kb)

Supplementary Figure 1

The receiver operating characteristic (ROC) curves for the three variables that had dynamic ultrasound measures that differed across SUI severity groups when looking at the change from rest to Valsalva. The area under the curve (AUC) and the sensitivity (Se) and specificity (Sp) of the optimal threshold are given in the table below the ROC curves (PNG 189 kb)

High-resolution image (TIF 892 kb)

Supplementary Figure 2

An illustration of modes 1 and 2 with normal curves depicting the distribution of all rest, squeeze, and Valsalva PC scores (color-coded as indicated in the right middle legend). Individual PC scores are depicted by points with outliers as open circles. The color map on the shapes (white showing the greatest displacement from the mean shape, located at 0 for each mode) reveal the aspects of urethral shape being described by each mode. The normal curves demonstrate a shift towards the left from rest to squeeze and a shift towards the right from rest to Valsalva. Relevant anatomy and the urethra’s general orientation are shown in the top right legend (PNG 121 kb)

High-resolution image (TIF 511 kb)

Supplementary Figure 3

An illustration of modes 5, 7, and 1 with normal curves depicting the distribution of all no, mild, and severe SUI PC scores (color-coded as indicated in the right middle legend). Individual PC scores are depicted by points with outliers as open circles. The color map on the shapes (white showing the greatest displacement from the mean shape, located at 0 for each mode) reveal the aspects of urethral shape being described by each mode. Mode 5 demonstrates a shift between no and severe SUI shapes while the mild straddle both distributions. Mode 7 demonstrates a shift between no and both SUI groups—mild and severe SUI distributions are almost identical. Finally, mode 11, like mode 5, only demonstrates a difference between no and severe SUI shape distributions. Relevant anatomy and the urethra’s general orientation are shown in the top right legend (PNG 259 kb)

High-resolution image (TIF 1130 kb)

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Routzong, M.R., Chang, C., Goldberg, R.P. et al. Urethral support in female urinary continence part 1: dynamic measurements of urethral shape and motion. Int Urogynecol J 33, 541–550 (2022). https://doi.org/10.1007/s00192-021-04765-3

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  • DOI: https://doi.org/10.1007/s00192-021-04765-3

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