Bladder wall elasticity in neurogenic bladder: Insights from shear wave ultrasound elastography and its correlation with functional and structural parameters of upper and lower urinary tract.

Abstract

Introduction: Children with neurogenic bladder (NB) exhibit increased bladder-wall stiffness, yet non-invasive tools to quantify this remain limited. In this study, we assessed whether shear-wave elastography (SWE) distinguishes NB from healthy bladder and explored its relationship with routine upper- and lower-tract investigations.

Methods: In this prospective single-centre study, children with NB and age-matched controls underwent bladder SWE. Young's modulus of elasticity (YME, kPa) was measured in the anterior bladder wall at two filling states: full bladder (100 % estimated capacity) and post-void. Median YME measurements were compared between patients and controls. Inter- and intra-group within-child change, i.e., ΔYME = (full - post-void), was calculated. Also, the YME values (at both states) were compared between binary patient sub-groups divided based on parameters of routine upper and lower urinary tract investigations including ultrasound, scintigraphy studies, micturating cystourethrogram and urodynamic study. Mixed-effects models with a random intercept for patient ID verified all comparisons while accounting for paired measurements.

Results: A total of 44 patients and 42 healthy controls were enrolled in the study. Median YME was higher in NB than controls at both bladder states: full bladder: 9.95 kPa vs 7.50 kPa (p = 0.0006); and, post-void: 9.30 kPa vs 6.80 kPa (p = 0.023). The within-child change, ΔYME, was small and highly variable (median + 0.68 kPa in NB vs + 0.15 kPa in controls; p = 0.27), indicating no systematic stiffening or relaxation after voiding. Both classical statistics and mixed effects modelling showed no significant differences in YME (full-bladder or post-void state) values across NB patient sub-groups stratified by variables including hydroureteronephrosis, vesicoureteral reflux, renal scarring, reduced GFR, bladder capacity, pressure, compliance, hostility, or detrusor overactivity.

Conclusion: Median YME values are higher in NB than in controls at both bladder states, yet the paired change (ΔYME) showed no meaningful inter-group or intra-group variation. Both classical statistics and mixed-effects models likewise detected no association between YME and the various clinical sub-groups. Therefore, until multicentric data confirm diagnostic thresholds, longitudinal reproducibility, and predictive value for upper-tract risk, SWE should be viewed only as a complementary research tool rather than a substitute for current gold standard investigations.