The Comparison between Various Formulae for Calculating the Residual Volume by Ultrasonography during Volume Change, and the Influence of Gender and Age

Kim, Ji Yong; Park, Jun Tag; Kim, Soon Chan

Abstract

PURPOSE: There have been few reports concerning the accurate formula for calculating the residual urine by ultrasonography. The aim of this study was to find the most applicable formula for measuring the quantity of the residual urine by ultrasonography in terms of capacity, age and gender.
MATERIALS AND METHODS
This study was carried out on 176 of 254 patients with voiding dysfunction. The mean age of the patients was 64.3+/-17.7 yrs, ranging from 4 to 88 yrs, with a M:F ration of 1.67:1. The ultrasonographic diagnostic equipment used was the HDI35000(ATL Co Ltd, United States). 13 formulae currently used in the calculation of residual urine by ultrasonography were used, and the results compared with the actual residual urine from urethral catheterization. The accuracy, percentage volume error and statistical significance of the formulae were compared in terms of the residual urines above and below 150ml from urethral catheterization, above and below the age of 50 and gender.
RESULTS
The Hakenberg formula gave the best accuracy(0.95+/-0.25), whereas the McLean formula gave the best percentage error with respect to volume(17.4+/-20.9). With the formulas of Griffiths and Hakenberg, the results had statistical significance. However, none of the formulae showed statistical significance with regard to the residual urine either above or below 150ml. Therefore, a formula constant of -4.5 was added to the Griffiths formula, as this had statistical meaning in both group. There were no differences in relation to age or gender with any of the formulae.
CONCLUSIONS
The Griffiths formula was relatively accurate in the volume change among the 13 formulae used. The addition of -4.5 as a constant to the formula gave statistical meaning to the residual urine, both above and below 150ml. Age and gender did not affect the correctness of the measurement.