Reliability of bladder volume measurement with BladderScan in paediatric patients.

OBJECTIVE: To evaluate the reliability of estimates of bladder volume (BV) in children made with the BladderScan BVI 2500 (BS) and their agreement with standard ultrasound (US) measurements. MATERIAL AND METHODS: BV was measured using both US and BS in 92 children (41 females, 51 males; age range 3 months to 16 years) who underwent standard US measurements for various reasons. Patients were stratified into three groups according to age (3-35, 36-83 and > 83 months) and BV (< 20%, 20-50% and > 50% of expected bladder capacity for age). US and BS measurements were compared by means of the percentage difference and Pearson's correlation coefficient (r); limits of clinical agreement were evaluated by means of Bland-Altman analysis. RESULTS: Overall, a difference of -12.9% and a correlation coefficient of r = 0.98 were found between US and BS. The percentage difference was higher in younger patients (-27.8%) and for low volumes (-24.8%). Correlation analysis confirmed this trend in different age (3-35 months, r = 0.74; 36-83 months, r = 0.93; > 83 months, r = 0.97) and BV (< 20%, r = 0.70; 20-50%, r = 0.94; >50%, r = 0.97) groups. Bland-Altman analysis showed large limits of clinical agreement between the two methods in terms of overall measurements (-45 to 29.3 ml) and in both age (-25.3 to 56.9 ml) and BV (-27.5 to 52.5 ml) groups. CONCLUSIONS: A good correlation between US and BS measurements of BV was found in children aged > 7 years and in those with a BV > 20% of expected bladder capacity. Thus, BS avoids the need for standard US equipment to assess BV for schoolchildren with voiding dysfunction. Nevertheless, a dedicated BS instrument should be used in younger children.