Ultrasonographic evaluation of bladder volume in children

Although ultrasound has been recently used to estimate bladder volume, several different formulae are used. We analysed the accuracy of ultrasound evaluation of bladder volume with an ultrasound scanner equipped with a videocassette recorder. We determined three dimensions of the bladder, i.e. depth (D), height (H) and width (W) by reviewing videotapes in 53 children. D×H×W (DHW) showed a good linear relationship with actual bladder volume (r=0.96). Estimation of bladder volume by the regression equation gave errors of 12.5±8.6% (mean±SD) with errors above 25% in only 6% of children. Estimation of the volume by simply multiplying DHW by a correction factor of 0.80 gave a greater error of 18.9±14.0% (P<0.001) with errors above 25% in 24% of children. Thus, the use of the formula volume (ml)=DHW (cm³)×0.68+4 was sufficiently accurate in the ultrasound estimation of bladder volume in children.