Evaluation of Bladder Dysfunction Outcomes Among Standardized Bladder Shapes in Children With Spina Bifida

To (1) propose standardized terminology for bladder shapes on fluoroscopic images in a pediatric spina bifida population and (2) determine if bladder shape is associated with filling pressures and other measures of bladder dysfunction. We hypothesized that oblong, trabeculated, and "Christmas tree" bladders would have higher filling pressures and worse bladder function (higher filling pressures; higher presence of vesicoureteral reflux, leakage, detrusor-external sphincter dyssynergia, and hydronephrosis) than smooth and round-shaped bladders.

We conducted a cross-sectional study of pediatric and adolescent patients with spina bifida who underwent video urodynamics (VUDS) at a tertiary center from July 2016 to June 2022. Representative fluoroscopic bladder images from the earliest available VUDS were categorized by unsupervised cluster analysis. Five urologists also determined standardized classifications for bladder shape (round, oblong, and "Christmas tree") and contour (smooth or trabeculated/diverticulated), which were applied to the bladder images. Bladder filling pressures and clinical measures of bladder function were compared among bladder shapes.

Four hundred seventeen patients with a median age of 2.6 years (IQR 0.4-8.0 years) were included. For the machine learning cluster analysis of bladder shape, clusters with more trabeculated-appearing bladders had higher filling pressures. For expert clinician classification, round trabeculated, oblong trabeculated, and "Christmas tree" bladders had higher filling pressures than round smooth and oblong smooth bladders, a difference that was statistically significant. Statistically significant differences were noted among bladder shapes for the presence of vesicoureteral reflux, leakage, detrusor-external sphincter dyssynergia, and hydronephrosis. Moderate and severe bladder dysfunction were present across all bladder shape clusters.

We established a standardized bladder shape nomenclature in children and adolescents with spina bifida. Higher bladder filling pressures are associated with trabeculations and "Christmas tree" appearance versus smooth contour, but not oblong versus round shape. Bladder shape alone does not appear to consistently differentiate the presence of hydronephrosis, vesicoureteral reflux, leakage, detrusor-external sphincter dyssynergia, or bladder dysfunction severity.