Objective: To evaluate bladder function in infants and children with no apparent voiding symptoms.
Subjects and methods: The study included 83 infants and children (51 boys and 32 girls, aged 3 days to 12 years) with no neurological and lower urinary tract pathology but who had undergone or were about to undergo surgery for upper urinary tract or other pathology. They were evaluated using slow-filling cystometry, with simultaneous electromyography recorded using surface electrodes on the perineum. The voiding variables were compared among groups categorized by age, sex and body weight.
Results: In boys and girls, respectively, the mean (SD) post-void residual urine volume (PVR) was 6.3 (3.9) and 5.4 (4.8) mL, the maximum detrusor pressure during voiding was 66.1 (13.1) and 56.6 (14.7) cmH2O and the maximum voiding pressure was 73.9 (16.6) and 62.7 (16.2) cmH2O. There was no significant difference in these variables between the sexes or between infants and children (P > 0.05). Detrusor instability (DI) was apparent in nine of 83 (10.8%) infants and children and occurred in the late filling phase. Bladder capacity increased with age and body weight (from 30 mL in neonates to 350 mL in 12-year-old children), and mean (SD) bladder compliance increased with age, from 3.6 (0.5) mL/cmH2O in infants to 13.3 (3.0) mL/cmH2O in older children, at a filling rate of 5-7 mL/min.
Conclusions: In these infants and children with no apparent voiding symptoms, most bladders were stable, DI could occur in the late filling phase of cystometry, voiding was nearly complete, the PVR being usually < 10 mL, and bladder capacity increased with age and body weight.