Reliability of bladder volume measurement with BladderScan® in paediatric patients

Abstract

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. 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. 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. 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.