The accuracy of three-dimensional bladder ultrasonography in determining the residual urinary volume compared with conventional catheterisation

Abstract

ObjectiveTo determine the accuracy of three-dimensional bladder ultrasonography (US, using the BVI 3000, Verathon, WA, USA) for determining the residual urinary volume, compared with the conventional catheterisation method.Patients and methodsWe conducted a cross-sectional study at day-care unit of a University hospital after obtaining approval from the Ethics Review Committee of the hospital. Thirty-four patients with lower urinary tract symptoms requiring cystometrography were included. The postvoid volume was measured by bladder US, with three readings taken, and then patient was catheterised using a 12-F Nelaton catheter to measure the urinary volume. The mean of the three readings was compared with the catheterisation volume.ResultsThe mean (SD) urinary volumes by US and catheterisation were 261 (186) and 260 (175) mL, respectively, and the correlation (r2) was 0.97. There was no effect of age, gender or body mass index on the accuracy of bladder US, which was accurate even when the urinary volume was ⩽100 mL.ConclusionThe bladder US estimate is as accurate as catheterisation for determining the postvoid residual urinary volume. Its accuracy was also comparable when the urinary volume is <100 mL, and there was no significant effect of age, gender and body mass index. This system could replace the more invasive catheterisation, and with excellent accuracy.

Can we replace the catheter when evaluating urinary residuals?

“…A study found 3D showed excellent correlation with catheterised volumes, especially for volumes <200 mL. There was more of a difference with higher volumes but these were not statistically significant …”

“…They are more user‐friendly than conventional two‐dimensional (2D) ultrasound and only require basic training. They are usually small and portable allowing for use on the ward at the bedside . The disadvantage of these scanners is that they do not always enable direct bladder imaging and therefore may lead to diagnostic errors.…”

“…9 Ultrasound is more expensive and requires an ultrasound machine and a trained professional. 10 The view of the bladder may be impaired by acoustic shadowing from the calcified interpubic disc. This is more likely in older women.…”

Assessment of Urinary Incontinence (UI) in Adult Patients

“…Jalbani and Ather [33] noted that the bladder scan estimate is as accurate as catheterization for determining the PVR urinary volume. Its accuracy was also comparable when the urinary volume is <100 mL, and there was no signiicant efect of age, gender and body mass index.…”

“…However, it is not considered useful in the evaluation of UI [33]. Ultrasound imaging can reliably be used to measure bladder neck and urethral mobility in cases of SUI but it is not routinely performed in the initial assessment of UI.…”