Assessing Bladder Volumes in Young Children Prior to Instrumentation: Accuracy of an Automated Ultrasound Device Compared to Real-time Ultrasound

Objectives: Automated bladder ultrasound (ABUS) devices are portable and designed to provide automated measurement of bladder volume. They are simple and require minimal training compared to conventional real-time ultrasound (RTUS). Their most common application in the acute pediatric setting is to assess bladder volumes prior to performing invasive urine collection such as suprapubic aspiration (SPA) in children younger than 2 years of age. However, data on ABUS in young children are limited. The aim of this study was to assess the repeatability and accuracy of one type of ABUS, the BladderScan, in measuring of bladder volume in children aged 0 to 24 months when compared with RTUS. Methods: Healthy children aged 24 months and younger were scanned twice, 1 hour apart, using ABUS and RTUS. ABUS readings were performed by two senior pediatric emergency physicians who both completed three readings for each child. The measurements were repeated using a second ABUS machine in case of machine variability. RTUS measurements were performed by a pediatric sonographer who was blinded to the ABUS results. ABUS and RTUS measurements were compared by Bland-Altman analysis to determine the repeatability coefficient (repeatability) and the limits of clinical agreement (accuracy). Results: Bladder volume measurements were performed on 61 children aged 0 to 24 months (31 males; mean +/- SD = age 11 +/- 6.2 months; range = 0 to 24 months) using both the ABUS and the RTUS. There was wide variation between ABUS and RTUS measurements. The repeatability coefficient within ABUS readings was 20 mL. By Bland-Altman analysis, the 95% limits of agreement between ABUS and RTUS were -31 to +19 mL. ABUS also detected no values between 0 and 10 mL. Conclusions: This study showed poor repeatability and accuracy in bladder volume measurements using BladderScan ABUS when compared to RTUS. The ABUS method does not appear to be a reliable method for assessing bladder volumes in children aged 0 to 24 months prior to bladder instrumentation. ACADEMIC EMERGENCY MEDICINE 2011; 18:816-821 (C) 2011 by the Society for Academic Emergency Medicine