This study aimed to explore the predictive value of multimodal ultrasound (MMU) for upper urinary tract damage (UUTD) in children with neurogenic bladder (NB), and to screen out the independent risk factors of UUTD in NB children, construct an early warning model, and further compare the predictive efficacy of the MMU-based model and urodynamic study (UDS) for UUTD.

A prospective clinical study was conducted on 87 NB children admitted to the First Affiliated Hospital of Zhengzhou University from January 2022 to December 2023. All children underwent comprehensive MMU examinations, with relevant indicators measured in both bladder filling and emptying states: in the filling state, vesical volume (VV), bladder wall thickness (BWT), anterior wall shear wave velocity (SWV), resistance index (RI), and vascularization index (VI) were detected; in the emptying state, VV and anterior wall SWV were measured, and ultrasound bladder compliance (△C) was calculated. Bilateral renal pelvis anteroposterior diameter (APD) and ureteral diameter (UD) were also measured for all subjects. According to the clinical classification criteria, the subjects were divided into the UUTD group and the non-upper urinary tract damage (NUUTD) group. Statistical analysis was used to compare the differences in clinical data, MMU parameters and UDS indicators between the two groups, screen independent risk factors for UUTD by regression analysis, construct an early warning model, and evaluate the predictive efficacy of each indicator and the model.

A total of 47 cases were in the UUTD group and 40 cases in the NUUTD group, with no significant differences in gender, age and body mass index between the two groups (all P>0.05). The total glomerular filtration rate (tGFR) of the UUTD group was (70.45±16.17) mL/min, with 38.30% hydronephrosis and 23.40% bilateral ureteral dilatation; the NUUTD group had no urinary system morphological changes, and the tGFR was (100.55±16.27) mL/min, with a significant difference in tGFR between the two groups (P<0.05). Compared with the NUUTD group, the UUTD group had significantly decreased filling VV, △C, VI, maximum bladder capacity (MCC) and bladder compliance (BC), and significantly increased emptying VV, mean BWT, filling SWV, emptying SWV, mean RI, maximum detrusor pressure during filling (Pdet.max) and detrusor leak point pressure (DLPP) (all P<0.05). Regression analysis showed that decreased BC, △C, VI, and increased DLPP, filling SWV, mean BWT were independent risk factors for UUTD in NB children (all P<0.05). Among all MMU parameters, filling SWV had the highest predictive efficacy for UUTD, with a critical value of 3.33 m/s, sensitivity of 72.34% and specificity of 92.50%.

The significant difference in tGFR between the two groups indicated that UUTD caused obvious renal function damage in NB children, and the abnormal changes of MMU parameters in the UUTD group reflected the structural and functional abnormalities of the bladder in NB children with UUTD, such as increased bladder wall thickness, decreased compliance, and abnormal vascular perfusion. The six independent risk factors screened out were closely related to the pathological changes of NB complicated with UUTD, and the high sensitivity and specificity of filling SWV suggested that it could reflect the degree of bladder wall fibrosis and stiffness in NB children, and thus effectively predict the occurrence of UUTD. MMU can comprehensively evaluate the bladder's morphological and functional status through multiple parameters, and its non-invasive characteristics make it more suitable for repeated examinations in children.

MMU can well predict the occurrence of UUTD in children with NB, and filling SWV has the highest prediction efficiency.