It is time to abandon "expected bladder capacity." Systematic review and new models for children's normal maximum...

Area of Science:

• Pediatric Urology
• Bladder Physiology
• Clinical Research Methodology

Background:

• Current benchmarks for child bladder capacity rely on simplified, age-based linear formulas.
• The actual normal bladder capacity and maximum voided volumes (MVVs) in children remain largely uncharacterized.
• Existing benchmarks may not accurately reflect physiological variations in children's bladder function.

Purpose of the Study:

• To systematically review and synthesize existing data on normal bladder capacity in children.
• To establish reliable models for children's normal maximum voided volumes (MVVs) based on empirical data.
• To compare these newly developed MVV models against commonly used age-based formulae.

Main Methods:

• A systematic review of computerized, manual, and grey literature was conducted up to February 2013.
• A multicenter, observational study included healthy children aged 5-14 years who completed a 3-day frequency-volume chart.
• Multivariate regression analysis was employed, considering maximum voided volumes (MVVs), diuresis, body measurements, and gender as variables.

Main Results:

• Twelve studies met the systematic review criteria, analyzing data from 514 children.
• Three distinct models for maximum voided volumes (MVVs) were constructed, demonstrating exponential relationships.
• Diuresis emerged as the most significant predictor of bladder capacity, surpassing age; agreement with existing formulae was poor.

Conclusions:

• Nocturnal and daytime maximum voided volumes (MVVs) have distinct clinical implications and should be interpreted separately.
• Diuresis is identified as the primary determinant of bladder capacity in children.
• The developed models provide a new benchmark for normal MVVs, highlighting the inadequacy of current clinical formulae.