Which method is the most reliable in determination of bladder capacity in children with idiopathic overactive bladder? A comparison of maximum voided volume, uroflowmetry and maximum cystometric capacity.
OBJECTIVE
To compare uroflowmetry, maximum cystometric capacity and maximum voided volume in terms of bladder capacity (BC) estimation in children with idiopathic overactive bladder.


MATERIALS AND METHODS
A total of 84 children with idiopathic overactive bladder were enrolled. Bladder diaries were kept by parents to measure maximum voided volume. The sum of voided volume and post-void residual urine represented uroflowmetric BC. Maximum cystometric capacity was recorded for each patient. Patients with and without urge incontinence and both sexes were compared, and correlations were tested between estimated capacities, patient age and continence status.


RESULTS
Mean age was 10.88 (range 6-16) years. There were 52 females and 32 males. A total of 48 patients had urge incontinence (group 1), and the remaining 36 (group 2) did not. Mean bladder capacities were 165.44ml for uroflowmetry, 204.37ml for cystometry and 260.07ml for bladder diary. Maximum cystometric capacity and capacity in terms of maximum voided volume by diary were significantly higher in patients without urge incontinence. There were significant correlations between age and all other variables, and between the presence of urge incontinence and all variables except maximum cystometric capacity. There were significant differences between bladder capacities estimated by the three methods; however, on age-adjusted re-analysis this significance was lost.


CONCLUSION
There is no significant difference between BCs estimated by uroflowmetry, maximum cystometric capacity and maximum voided volume in children with idiopathic overactive bladder. Bladder diary is a reliable and non-invasive way of estimating BC in this patient population.