Comparison of ultrasonographic and radiographic measurements of bladder dimensions and volume determinations

The purpose of this study was to compare the linear dimensions of the bladd er measured by ultrasonographic and radiographic methods and the accuracy o f these methods for evaluation of bladder volume. Forty dogs were included in this study. Each dog was placed in right lateral recumbency and a plain lateral caudal abdominal radiograph was made. The bladder length and depth were measured in centimetres from the radiograph, taking into account magni fication errors. Immediately after radiography was completed, ultrasonograp hic measurements of bladder length and depth on longitudinal section were m easured in centimetres. The bladder was then emptied by catheterisation and the actual urine volume measured. 'Best subsets' analysis indicated that r adiographic and ultrasonographic bladder lengths were the best predictors o f actual bladder volume. Formulae were derived from radiographic and ultras onographic bladder dimensions for estimating bladder volume. The formula us ing radiographic measurements was found to be a better predictor of actual bladder volume than the formula derived from ultrasonographic measurements, since it had higher F and lower error mean square values.