Bladder Physiology in Newborns

Physiological Parameters

• Water contributes nearly 75% of body weight in term infants, compared to 90% in premature infants and 50% in adults 1, 2
• Renal glomerular surface area available for filtration is small in term neonates compared to older infants and adults 1
• Maximum urinary concentrations reach up to 700 mosm/l in term infants, compared to 1200 mosm/l in adults 1

Clinical Considerations

• When performing clean intermittent catheterization in newborns, volumes less than 30 ml per catheterization for the majority of catheterizations for 3 consecutive days may indicate adequate bladder emptying 3, 4
• High water turnover in neonates (compared to adults) affects fluid balance and urine production, which impacts bladder filling rates 1, 2