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Some new insights into bladder function in infancy
C K Yeung1, M L Godley, C K Ho
1Department of Surgery, Chinese University of Hong Kong, Prince of Wales Hospital.
Insights
Normal infant bladder function is stable, emptying nearly completely. Micturition occurs during wakefulness or arousal, not quiet sleep, challenging the uninhibited bladder concept.
Area of Science:
- Pediatric Urology
- Neuroscience
- Physiology
Background:
- The traditional view posits a completely uninhibited infant bladder.
- Understanding normal bladder function and micturition patterns in infants is crucial for pediatric urology.
- Infant voiding mechanisms require further elucidation.
Purpose of the Study:
- To evaluate normal bladder function and micturition patterns in infants.
- To investigate the relationship between bladder filling, detrusor pressure, and voiding efficiency.
- To determine the sleep state associated with micturition in neonates and infants.
Main Methods:
- Natural filling cystometry was performed on 21 infants (mean age 5.9 months) without lower urinary tract pathology.
- Micturition patterns were simultaneously observed with polysomnography in 26 healthy neonates (mean age 7.4 days).
- Key parameters measured included bladder capacity, detrusor pressure, voiding efficiency, and associated sleep states.
Main Results:
- Infant bladder capacity averaged 42-53 mL, with a voiding efficiency of 0.86-0.91.
- Detrusor pressure during voiding ranged from 95-120 cmH2O; discoordinated urinary flow was noted in 10 infants.
- Micturition exclusively occurred during wakefulness or arousal from sleep, never during quiet sleep.
Conclusions:
- The infant bladder demonstrates stability and near-complete emptying, contradicting the 'uninhibited bladder' theory.
- Incomplete coordination during voiding may be a normal finding in infants.
- Cortical arousal in response to bladder fullness, even in neonates, suggests a more complex control mechanism than previously thought, with implications for enuresis management.
Objectives:
To evaluate normal bladder function and micturition patterns in infants.
Patients, Subjects And Methods:
Twenty-one infants (16 boys, five girls; mean age 5.9 months) with no lower urinary tract pathology underwent natural filling cystometry. Micturition patterns were also observed simultaneously with polysomnography in 26 healthy neonates (16 boys, 10 girls; mean age 7.4 days).
Results:
In infants, cystometry showed (95% CI) a capacity of 42-53 mL, a maximum rise in detrusor pressure during voiding of 95-120 cmH2O and a voiding efficiency (voided volume/capacity) of 0.86-0.91. On micturition, urinary flow was discoordinated from peak detrusor pressures in 10 infants. Detrusor instability occurred in one of 21 infants. Micturition was observed only during wakefulness or on arousal from sleep. In neonates, 17 of 61 recorded voids (28%) were during full wakefulness and 44 (72%) during arousal from sleep. Notably, none of the recorded voids occurred during quiet sleep.
Conclusions:
The normal infant's bladder was stable and emptied almost completely. Voiding with incomplete co-ordination between detrusor contraction and urinary sphincter relaxation could be normal. Micturition never occurred during quiet sleep. There was cortical arousal in response to a full bladder even in new-born infants. This contradicts the traditional concept of a totally uninhibited bladder in infancy. There are potential implications for the management of children with nocturnal enuresis.