Accuracy of Bladder Scanner for the Assessment of Postvoid Residual Volumes in Women With Pelvic Organ Prolapse.

Objectives: The aim of the study was to evaluate the accuracy of the bladder scanner in assessing postvoid residual (PVR) volumes in patients with pelvic organ prolapse (POP).
Methods: We performed a prospective parallel cohort study evaluating the accuracy of the BVI 3000 bladder scanner in patients with POP. Patients with POP to the hymen were offered inclusion. Primary outcome was the absolute difference between bladder scanner and catheterization PVR. We also investigated the effect of prolapse stage on bladder scanner accuracy. A prevoid bladder volume was obtained by bladder scan. Subjects voided volume was then collected. A PVR was obtained by bladder scan, followed by a PVR by catheterization. Descriptive statistics, Wilcoxon signed-rank test, linear regression analysis, and sensitivity/specificity analysis were performed.
Results: We enrolled 87 subjects. There was a statistically significant difference between catheter and bladder scan PVR, with an absolute median difference of 20 mL (SD = 37.7), P < 0.001. Linear regression analysis showed a difference between mild and advanced prolapse groups. The regression coefficients of the mild prolapse group and advanced prolapse were 0.91 (confidence interval = 0.75-1.06) and 0.66 (confidence interval = 0.54-0. 78), P = 0.015, respectively, indicating a deterioration of accuracy of the bladder scanner for advanced prolapse. The sensitivity of the bladder scanner identifying catheterized PVR volumes less than 100 mL was 93.7%. For catheter PVRs greater than 100 mL, the specificity of the bladder scanner was 72.7%.
Conclusions: Bladder scanner PVRs are less accurate in advanced prolapse, and PVRs of greater than 100 mL should be confirmed by catheterization.