What volume can a child normally store in the bladder at a safe pressure?

Area of Science:

• Pediatric Urology
• Urodynamics
• Pediatric Nephrology

Background:

• Assessing normal bladder volume storage at safe pressures is vital for pediatric urological health.
• Previous studies lacked comprehensive data on bladder storage capacity relative to pressure in children.

Purpose of the Study:

• To establish normal bladder storage volumes at safe detrusor pressures in children.
• To propose criteria for evaluating bladder storage characteristics in pediatric patients.

Main Methods:

• Reviewed 923 pediatric urodynamic studies, focusing on 69 normal examinations in children (17 boys, 52 girls).
• Performed continuous intermediate flow water cystometrograms to measure total bladder capacity, resting pressures, and volume stored at specific detrusor pressures.
• Calculated patient ages and body surface areas to analyze storage capacity independently of these factors.

Main Results:

• Over 95% of children could store 98.1% of their total bladder capacity at detrusor pressures < 20 cm. water.
• 99.9% of total bladder capacity was storable at detrusor pressures < 30 cm. water, irrespective of age or body surface area.
• A formula for minimal acceptable total bladder capacity was derived: 16(age) + 70 ml.

Conclusions:

• Children can safely store a significant majority of their bladder volume at low detrusor pressures.
• The findings provide objective criteria for assessing normal bladder storage function in pediatric urodynamics.
• Established parameters can aid in diagnosing and managing conditions affecting bladder storage in children.