Abstract: Objective To evaluate the red blood cell stability and microbiological safety of umbilical cord blood (UCB) stored in citrate phosphate dextrose adenine-1 (CPDA-1) anticoagulant preservative solution at 2~6 ℃ for up to 35 days, providing experimental evidence for its use in predeposit autologous transfusion during neonatal cardiac surgery and other clinical scenarios. Methods Within an integrated prenatal-postnatal diagnosis and treatment model for congenital heart disease, UCB samples were collected from 60 neonates prenatally diagnosed with CHD. The samples were randomly divided into five groups. After storage for 7, 14, 21, 28, and 35 days, routine blood counts, electrolytes, free hemoglobin, hemolysis rate, and microbial contamination were measured. Results There were no significant baseline differences among groups before storage. During storage, red blood cell count, hemoglobin, hematocrit, platelet count, and sodium and calcium ion concentrations showed no significant changes. Potassium, free hemoglobin, and hemolysis rate all increased significantly with prolonged storage time (P<0.05). Post-hoc analysis revealed that potassium level rose steadily from day 7 onwards, while free hemoglobin and hemolysis rate increased significantly after 21 days of storage. Bacterial contamination with Escherichia coli occurred in 1 case (1.7%) among all samples. Conclusion Under standardized collection and storage protocols, UCB stored in CPDA-1 anticoagulant preservative solution for up to 35 days showed progressive potassium accumulation and hemolysis, yet key quality indicators remained within acceptable ranges and microbiological safety was controllable. This study supports that UCB represents a safe and feasible autologous blood source for neonates, particularly those with congenital heart disease requiring time-limited surgery.

Key words: Umbilical cord blood, CPDA-1 anticoagulant preservative solution, Predeposit autologous transfusion, Hemolysis rate