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.

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.