Normal Post-Void Residual Volume in Children
Normal post-void residual (PVR) volume in children is typically ≤20 mL, with most healthy children having a median PVR of 0-5.5 mL depending on age. 1, 2, 3
Age-Specific Normal Values
Infants and Toddlers (0-3 years)
- At 6 months to 1 year: Median PVR is 5.5-6 mL 2, 3
- At 2 years: Median PVR is 4 mL 3
- At 3 years: Median PVR is 0 mL 2, 3
- Mean PVR across this age range remains low at 3-4 mL per 4-hour observation period 3
Preschool Children (4-6 years)
- Mean PVR: 12.2 ± 20.3 mL (median 5.5 mL) in healthy kindergarteners 1
- At 6 years: Median PVR is 2 mL 2
- PVR decreases as children age, particularly after bladder control is established 1, 2
Adolescents (12-18 years)
- Males aged 12-14 years: 90th percentile is 20 mL (7% of bladder volume); 95th percentile is 30 mL (8% of bladder volume) 4
- Males aged 15-18 years: 90th percentile is 20 mL (7% of bladder volume); 95th percentile is 30 mL (11% of bladder volume) 4
- Females aged 12-14 years: 90th percentile is 25 mL (9% of bladder volume); 95th percentile is 35 mL (11% of bladder volume) 4
- Females aged 15-18 years: 90th percentile is 35 mL (10% of bladder volume); 95th percentile is 45 mL (13% of bladder volume) 4
- PVR increases with age and is higher in females than males during adolescence 4
Clinical Thresholds for Abnormal PVR
Abnormal PVR is defined as >20 mL on repeat measurements without bladder overdistention in preschool and school-age children. 1
- For adolescents: Values above the 90th percentile warrant repeat measurement and monitoring; values above the 95th percentile may require further investigation 4
- PVR >100 mL suggests incomplete bladder emptying requiring intervention across all pediatric age groups 5
- Defining abnormality as >10% of bladder capacity is less reliable than using absolute volume thresholds 1
Critical Measurement Considerations
Measurement Reliability
- Single PVR measurements are unreliable due to significant intra-individual variability 1, 6
- Repeat PVR measurement 2-3 times in the same setting while the child is well-hydrated is essential for accuracy 6, 5, 1
- Measure within 5 minutes after voiding when voided volume exceeds 50 mL 1
- The correlation between consecutive PVR measurements is low (r = 0.13-0.34), making single measurements inadequate for clinical decisions 1
Factors Affecting PVR Values
- Bladder overdistention (defined as bladder capacity ≥115% of expected) significantly increases PVR and produces nonbell-shaped uroflowmetry curves 7
- Age: PVR decreases as children mature and acquire bladder control 1, 2
- Excessive fluid intake before assessment increases bladder overdistention rates (13.8% vs 4.9% with regular hydration) 1
- Gender in adolescents: Females have higher PVR than males, requiring gender-specific reference values 4
Common Pitfalls to Avoid
- Never base clinical decisions on a single PVR measurement without confirmation, as variability renders isolated values unreliable 6, 1
- Avoid measuring PVR when bladder is overdistended (>115% expected capacity), as this artificially elevates values and distorts voiding function assessment 7
- Do not use percentage of bladder capacity alone to define abnormal PVR; absolute volume thresholds (>20 mL) are more clinically useful 1
- Ensure adequate but not excessive hydration before measurement, as both extremes compromise accuracy 1