Spinal anesthesia-induced hypotension is a common and clinically significant complication in geriatric patients. Accurate preoperative assessment of intravascular volume status may help identify patients at risk. Internal jugular vein (IJV) ultrasonography is a noninvasive and easily applicable bedside method that reflects venous volume status. This prospective observational study aims to evaluate the role of preoperative IJV ultrasonographic measurements in predicting hypotension following spinal anesthesia in geriatric patients. Patients aged 65 years and older undergoing elective surgery under spinal anesthesia will be included. Preoperative IJV diameter, cross-sectional area, and collapsibility index will be measured using ultrasonography. Hemodynamic parameters will be monitored intraoperatively, and the occurrence of hypotension after spinal anesthesia will be recorded. The predictive value of IJV ultrasonographic parameters for post-spinal hypotension will be analyzed