Lower urinary tract function in childhood; normal development and common functional disturbances.

This review aims to provide researchers and clinicians involved with the adult lower urinary tract with background knowledge regarding the early development of bladder function and its most common disturbances in childhood. Bladder development begins in weeks 4-6 and the detrusor muscle is formed during weeks 9-12 of gestation. Higher CNS centres are involved in micturition at birth, and the infant usually wakes up, at least briefly, to void. Voiding during the first years of life is often incomplete, owing to detrusor-sphincter dyscoordination, but this disappears when bladder control is attained. Approximately 5-10% of 7-year-old children suffer from daytime incontinence and/or nocturnal enuresis, and a few per cent of them will not outgrow it. Daytime incontinence in childhood is usually attributable to detrusor overactivity, although it is unclear to what extent it is the detrusor or the micturition reflex per se that is overactive. Enuresis - nocturnal incontinence - is caused by either nocturnal polyuria and/or nocturnal detrusor overactivity, in both cases combined with high arousal thresholds. Bladder problems in childhood constitute a risk factor for the development or persistence of bladder problems in adulthood.