Especially in recent years, the use of point-of-care ultrasound by non-radiologist clinicians has become widespread. Point-of-care ultrasound provides rapid responses to the problems of critically ill patients at the bedside. This technique has many important advantages, including being non-invasive, cheap, repeatable, painless, and radiation-free. Numerous studies have revealed the most important clinical benefits of point-of-care ultrasound use by pediatric intensive care providers. The inferior vena cava is a vessel that is highly sensitive to fluid changes. The inferior vena cava diameter can be measured by a point-of-care ultrasound, and represents a critical parameter in assessing the patient’s fluid status. The inferior vena cava collapsibility index (in spontaneously breathing patients) and the inferior vena cava distensibility index (in mechanically ventilated patients) are calculated by determined formulas by using maximum and minimum diameters of the inferior vena cava. The indices are important guides for pediatric intensive care providers for managing their patients’ fluid treatment. Although some authors claim it is not a reliable method, the technique is coming to fore in intensive care units day by day, and has an increasing trend among pediatric intensive care specialists. Here, we aim to give detailed information on the ultrasonographic inferior vena cava diameter measurement methods, and calculations of the inferior vena cava collapsibility index and inferior vena cava distensibility index, and emphasize the importance of a noninvasive, bedside, and objective method of detecting the volume status of critically ill patients for pediatric intensive care specialists according to the published literature.