Experience with portable ultrasound equipment and measurement of urine volumes: inter-user reliability and factors of patient position.

A portable ultrasound unit has been developed that provides a noninvasive technique to measure urine volume. We assessed the effect of patient position on the accuracy of measurements as well as inter-user reliability and user training. There were 63 ultrasound measurements of urine volume made by a trained and an inexperienced examiner, and the values were compared to true volumes obtained by catheterization in 16 adults with a neurogenic bladder. Subjects were tested in the seated and supine positions. Correlation for ultrasound volumes between the trained and inexperienced examiners was highly significant. Accuracy and precision of the ultrasound measurements were not affected by patient position. Thus, little training is necessary to use this instrument, inter-user reliability is good, and accuracy and precision are clinically acceptable whether patients are in the seated or supine positions.