Ultrasonic estimation of bladder weight as a measure of bladder hypertrophy in men with infravesical obstruction: a preliminary report.

The aim of the present study was to evaluate the usefulness of ultrasonic estimation of bladder weight as a measure of bladder hypertrophy using transabdominal ultrasonography in men with infravesical obstruction. Ultrasonically estimated bladder weight (UEBW) was calculated from the thickness of the bladder wall measured ultrasonically and the intravesical volume at the ultrasonic measurement, assuming a spheric bladder. There was a statistically significant correlation (r = 0.970, P <0.001) between the actual bladder weight of cadaver bladders and the UEBW. The UEBW did not change with bladder filling. The UEBW in the obstructed group (group O, 49.7 +/- 19.5 g, mean +/- SD) was significantly greater than that in the normal control group (group NC, 25.6 +/- 5.7 g; P <0.001) or the nonobstructed group (group NO, 28.4 +/- 4.2 g; P <0.001). The greatest UEBW was 34.8 g in group NC and 35.2 g in group NO, whereas 94% (45 of 48) of group O had a UEBW greater than 35.0 g. In all 5 patients with benign prostatic hyperplasia (BPH), the increased UEBW decreased to a normal control level at 3 months after treatment of BPH. This new noninvasive method may be useful in investigation of bladder hypertrophy.