Clinical Validation of a Blood Loss Monitoring System

This observational study aims to evaluate the practicality of a novel multifunctional intraoperative blood loss monitoring system in real-world surgical settings. The primary questions it seeks to address are: Using the direct measurement method as the reference standard, what is the magnitude of measurement error of the monitoring system, and does it tend to overestimate or underestimate blood loss? Does the monitoring system demonstrate superior accuracy compared with visual estimation, the gravimetric method, and the hemoglobin concentration-based method? During surgery, intraoperative blood loss will be measured simultaneously using five approaches: the novel multifunctional monitoring system, the direct measurement method, visual estimation, the gravimetric method, and the hemoglobin concentration method. These measurements will be conducted without interfering with the surgical procedure.

Inclusion Criteria: * Patients undergoing elective urological or general surgical procedures * Age 18 years or older * Preoperative hemoglobin concentration available * Intraoperative blood loss assessment required during surgery Exclusion Criteria: * Patients with incomplete intraoperative blood loss measurement data, * Severe hemolysis or other conditions that may affect hemoglobin measurement * Emergency surgery * Intraoperative blood loss assessment required during surgery 24 hours after surgery * Refusal to participate, when applicable