INTRAOBSERVER AND INTEROBSERVER VARIANCE IN THE MEASUREMENT OF ULTRASOUND-ESTIMATED BLADDER WEIGHT

Recently, we reported that ultrasound-estimated bladder weight (UEBW) could be used as a noninvasive tool in evaluating the degree of bladde r hypertrophy, This study was designed to test the reproducibility of its measurement. The overall mean UEBW of the initial measurement and that of the second one by one observer in 36 cases was 42.8 +/- 22.6 g and 42.9 +/- 22.6 g, respectively. The paired differences between two measurements ranged from -3.4 to 2.7 g, with a mean difference of onl y -0.1 g, The interobserver variance was also slight. The paired diffe rences between UEBW measurements derived from the two observers in 32 cases ranged from -6.0 to 7.9 g, with a mean difference of only 0.1 g, The Cochran's test statistic of the measurements of UEBW was 0.142 fo r one observer and 0.130 for two, which were less than its 5% critical value. Due to these favorable characteristics, UEBW could be reliable tool for the investigation of bladder hypertrophy with a sufficient r eproducibility. (C) 1998 World Federation for Ultrasound in Medicine & Biology.