The aim of the study is to compare the lateral decubitus and upright sitting positions in determining the intervertebral space measured by ultrasound in participants whose body mass index was greater than 30 and older than eighteen years old. Additionally, comparison of the sagittal and long-axis paramedian oblique planes in determining the intervertebral space measured by ultrasound in this group of volunteers. Furthermore, assesment of the reliability of measurements performed by practitioners with varying levels of ultrasound experience.