To compare the accuracy using the Bladder Scanner portable ultrasonographic device to measure bladder volume with measurement by intermittent catheterization (IC) in patients with neurogenic bladder.

Prior to implementation of the study, nurses were trained in the use of the AvantSonic Bladder Scanner Z5 portable ultrasonographic device. Bladder volume in patients was assessed by a nurse with the scanner 3 times consecutively, and the median value was reported. A second nurse, blinded to the scanner result, then catheterized the patient's bladder. A third nurse, similarly blinded to the scanner result, measured the urine volume in a 500 mL or 1000 mL graduated cylinder and reported the value. A prospective comparison of the urine volumes assessed by ultrasound and measured by IC. Each patient served as her/his own control.

In total of 46 patients with neurogenic bladder were repetitively assessed with the Bladder Scanner prior to IC between November 2017 and March 2018, and 521 pairs of data were obtained. The mean age of patients was 35.4 years (range 9 to 75).The median bladder volume measured using bladder scanner and IC was (330.5±6.8) mL and (336.8±6.9) mL, respectively. The mean difference was 30.7 mL. The correlation coefficient for volumes measured by scanning and catheterization was 0.927 (p < 0.0001, 95% confidence interval: 26.2-35.2). The median bladder volume of 60 pairs of data from 16 patients with abnormal bladder shape after augmentation cystoplasty (AC) measured using bladder scanner and IC was (249.1±17.2) mL and (357.8±21.1) mL, respectively. The mean difference was 118.2 mL. The correlation coefficient for volumes measured by scanning and catheterization was 0.683 (p < 0.0001, 95% confidence interval：89.2-147.1).The median bladder volume of 461 pairs of data from 30 patients with normal bladder shape measured using bladder scanner and IC was (340.3±7.3) mL and (333.9±7.4) mL, respectively. The mean difference was 19.9 mL. The correlation coefficient for volumes measured by scanning and catheterization was 0.982 (p < 0.0001, 95% confidence interval:17.8-22.0).Therefore, using the bladder scanner resulted in underestimation or overestimation for patients with abnormal bladder shape after AC.

This study showed that the AvantSonic Bladder Scanner Z5 offered an accurate and reliable alternative to catheterization for estimating bladder volume.

The accuracy is sufficient for most clinical purposes.  The results also demonstrated bladder shape played a critical effect on the accuracy of measurement using the bladder scanner.