Agreement and Reliability of Patient-measured Postvoid Residual Bladder Volumes

Abstract

BackgroundPost-void residual bladder volume (PVR) measurement in the non-healthcare setting is a valuable opportunity for remote monitoring of voiding dysfunction patients. We hypothesized that PVR self-measurement using a smart-device portable ultrasound system with artificial intelligence would demonstrate high reliability, strong agreement with provider measurement, and be preferred over provider measurements. MethodsPatients were enrolled during outpatient Urology visits. PVRs were measured in triplicate by providers using each of the following: an FDA-cleared (standard) bladder scanner, the portable ultrasound probe using ultrasound images (ButterflyTM US image mode), and the portable ultrasound probe using abstract images (ButterflyTM abstract mode). Subjects self-measured PVRs in triplicate using both imaging modes and reported their experiences via questionnaire. Reliability was assessed via intraclass correlation (ICC). Agreement between methods was assessed via Bland-Altman analyses using a clinically acceptable difference threshold of 50 mL. Results50 patients were enrolled. ICCs ranged from 0.95-0.98 for each method. 95% limits of agreement between standard bladder scanner and patient self-measurement were -71.73 mL and 86.73 mL using ButterflyTM US image mode and -93.84 mL and 112.52 mL using ButterflyTM abstract mode, respectively. Most patients preferred self-measurement over provider measurement (74% vs 26%, respectively). ConclusionsPatient self-measurement of PVR using smart-device integrated portable ultrasound probes is feasible, reliable, and preferred by patients. Limits of agreement between patient self-measurement and standard bladder scanner measurements exceeded our clinically acceptable difference threshold, though the inherent error of ultrasound-based bladder volume measurements should be considered. Longitudinal PVR assessments in non-healthcare settings may facilitate remote monitoring of voiding dysfunction patients.