Intra-observer repeatability when assessing the foetal urinary bladder volume by the Virtual Organ Computer-aided AnaLysis and SUM-OF-CYLINDERS methods: A pilot study

Abstract

Introduction The aim of this study was to compare the intra-observer repeatability when using two different methods for estimating the volume of foetal urinary bladders. Method The urinary bladders of 20 foetuses were documented by three-dimensional ultrasound. Standard deviation was compared when the volumes of identical bladder images were repeatedly estimated using the Virtual Organ Computer-aided AnaLysis and the experimental SUM-OF-CYLINDERS methods. Results No systematic deviation was found between the estimated volumes when using these two methods. Standard deviation was smaller for the SUM-OF-CYLINDERS compared to the Virtual Organ Computer-aided AnaLysis method (p < 0.0001). In relation to bladder volumes of 5–25 ml, standard deviation was 11–14% for the Virtual Organ Computer-aided AnaLysis and 4–5% for the SUM-OF-CYLINDERS method. Conclusions Using three-dimensional ultrasound images adapted for the Virtual Organ Computer-aided AnaLysis method, foetal urinary bladder volumes can also be estimated using the SUM-OF-CYLINDERS method. The SUM-OF-CYLINDERS method employs technical advances which may result in a lower standard deviation and therefore higher intra-observer repeatability.