Agreement and Reliability of Patient-measured Postvoid Residual Bladder Volumes

OBJECTIVE To assess the reliability, agreement with provider measurement, and patient preferences regarding patient self-measurement of postvoid residual bladder volume (PVR). PVR measurement in the nonhealthcare setting is a valuable opportunity for remote monitoring of voiding dysfunction patients. We hypothesized that patient self-measurement of PVR 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. METHODS Patients 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 (Butterfly US image mode), and the portable ultrasound probe using abstract images (Butterfly abstract mode). Subjects self-measured PVRs in triplicate using both imaging modes and reported their experiences via questionnaire. Reliability was assessed via intraclass correlation. Agreement between methods was assessed via BlandAltman analyses using a clinically acceptable difference threshold of 50 mL. RESULTS Fifty patients were enrolled. Intraclass correlations ranged from 0.95 to 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 Butterfly US image mode and - 93.84 mL and 112.52 mL using Butterfly abstract mode, respectively. Most patients preferred self-measurement over provider measurement (74% vs 26%, respectively). CONCLUSION Patient 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 nonhealthcare settings may facilitate remote monitoring of voiding dysfunction patients. UROLOGY 184: 62-68, 2024. Published by Elsevier Inc.