Bladder function in infants. A urodynamic and radiologic study

Abstract: Objective: The aims of the present study were to establish a reference for urodynamics in infancy, to study the urodynamic pattern of infants with urinary tract infection (UTI) and of infants with dilating vesicoureteral reflux (reflux), and to evaluate if bladder dysfunction was occurring in these conditions. In addition, the possibilities to identify bladder instability in infants at voiding cystourethrography (VCU) were evaluated.Subjects and methods: With videocystometry, a method combining morphological (VCU) and functional (cystometry) investigation, we studied prospectively 37 asymptomatic infants with a hereditary risk of reflux, 16 infants with dilating reflux, and 158 infants with first time UTI. Morphology of the bladder and urethra and occurrence of reflux were related to urodynamics. Electromyography (EMG) of the pelvic floor was recorded and compared to simultaneous detrusor contraction during voiding. Results: 31/37 asymptomatic infants had no reflux and could be considered as healthy. Early premature voiding was found in 3 of the 31. Bladder instability was not common (13%) in healthy subjects but frequent in infants with dilating reflux (81%) and in infants with UTI (66%). Bladder instability could be identified by radiological signs at VCU. The peak voiding detrusor pressure was significantly higher in male than female infants in each study. Male infants had higher peak voiding pressure than reported in older children. The high peak voiding pressure in male infants was associated with low bladder capacity. In males with small bladder capacity (less than 40 ml), peak voiding pressure was even higher in males with dilating reflux. An increased EMG activity of the pelvic floor was frequently noted during voiding both in healthy and in symptomatic infants. Conclusions: The urodynamic pattern in healthy non refluxing subjects with hereditary risk of reflux is characterised by small bladder capacity, high voiding pressure especially in males, and dyscoordination during voiding as indicated by increase in EMG activity, whereas bladder instability is uncommon. The high frequency of instability seen in infants with dilating reflux and in infants investigated after first time UTI can therefore be considered as a sign of bladder dysfunction. The high voiding pressures at small capacity seen in infants with dilating reflux also indicate bladder dysfunction. Bladder instability in infants can be identified at VCU.