The voiding pattern in healthy pre- and term infants and toddlers: a literature review

Toilet training in Western culture starts between 18 and 24 months. At this age, a child is assumed to have procured the competences needed for bladder control. Since the knowledge of reference values of a normal micturition serves as a guide to diagnose urologic pathology, the aim of this systematic review is to obtain a more comprehensive picture of normal voiding pattern in healthy infants, who have not yet reached bladder control. The systematic literature search was performed in two databases. This systematic review was conducted by the preferred reporting items for systematic reviews and meta-analyses (PRISMA statement). Twenty-one studies were selected that demonstrate factors associated with voiding pattern. Diuresis, interrupted voiding, post-void residual urine and voiding frequency are parameters decreasing with age. Bladder capacity, the lowest volume triggering micturition, flow rate, voiding volume and the level of awake voiding expand with age.

When evaluating the voiding pattern in infants, the normal evaluation of micturition parameters in healthy normal developing infants must be taken into consideration.

• Different voiding parameters in healthy infants who are not yet toilet trained are reported. • Voiding was believed to be induced by a constant bladder volume, while nowadays, it is detected that infants possess a functional spino-pontospinal voiding pathway.

• Arousal was detected in less than 60 % of all preterm micturitions, while it was present in more than 90 % of the micturitions of healthy "term" infants. • Voided volume, bladder capacity, and flow rate tend to increase with age. In contrast, voiding frequency, post-void residual urine, and interrupted voiding diminishes with an increasing age.