The inferior vena cava ultrasound (IVC) is a non-invasive method used to estimate the patient’s volemic status and support in fluid therapy. A frequently adopted technique to assess fluid responsiveness is the passive leg raise (PLR) maneuver, which improves venous return through lower limbs. However, the reliability of ultrasound measurements depends on the operator’s experience, acquisition conditions, vein motion and non-uniform pulsatility. In this context, the aim of this study was to evaluate the reliability and repeatability of IVC ultrasound measurements performed using VIPER real-time segmentation software, which provides the diameter, caval index (CI), cardiac caval index (CCI) and respiratory caval index (RCI).