Radionuclide voiding patterns in children with vesicoureteral reflux

The purpose of this study was to evaluate bladder function in children with vesicoureteral reflux (VUR) by means of indirect radionuclide cystography (IRNC), and to investigate whether IRNC can identify those children with voiding dysfunction. The study enrolled 74 neurologically intact children, 14 boys and 60 girls aged 2-14 years, with VUR documented using contrast micturating cystourethrography as the initial method. In all patients, IRNC was performed using technetium-99m diethylene triamine penta-acetate (DTPA). Based on the urodynamic findings, three groups were distinguished: a group with VUR and normal urodynamic findings (n=27), a group with VUR and detrusor hyper-reflexia (n=43) and a group with VUR and detrusor-sphincter dyssynergia (n=4). A control group comprised 64 healthy children, aged 2-13 years, without any symptoms of lower urinary tract dysfunction. The dynamics of bladder emptying were studied in the posterior view after intravenous injection of 37 MBq/10 kg b.w. DTPA, with acquisition of 90 2-s frames during voiding. The parameters evaluated were: voided urine volume (W), bladder capacity, functional bladder capacity (FBC), residual urine, voiding time, average flow rate, peak flow rate (PFR) and ejection fraction (EF). With regard to the final urodynamic diagnosis, FBC, PFR and EF were found to be significant IRNC predictor variables using the logistic regression method. If abnormality on at least two of the three significant predictor variables was taken as the criterion of voiding dysfunction, the overall sensitivity, specificity and accuracy of IRNC in the detection of voiding dysfunction were 81%, 78% and 80%, respectively. Three radionuclide voiding patterns were detected in children with VUR: (1) a normal voiding pattern characterised by normal FBC with near-normal PFR and EF values, (2) a markedly reduced FBC with significantly reduced VV, PFR and EF values (in children with bladder instability), and (3) a higher bladder volume with a near-normal value for PFR and a slightly reduced or near-normal EF (in children with detrusor-sphincter dyssynergia). This study confirmed the association between lower urinary tract dysfunction and congenital VUR. IRNC was found to be a simple, non-invasive method which allows reliable differentiation of voiding patterns in patients with VUR. IRNC can be used as a first-line method for screening in children with VUR to identify those with abnormal voiding patterns.