2.2. Methods and data collection
STERILE, GROUP B
In group A, the neonate was successfully delivered. Before the newborn infant uttered the first cry, the umbilical cord was clamped using the first hemostatic clamp and cut off. The umbilical cord was clamped 3 to 4 cm away from the first hemostatic clamp using another hemostatic clamp, and sufficient umbilical blood was reserved for blood gas analysis. The UCB for separating hematopoietic stem cells was first collected. The cord blood collection procedure was as follows: the UCB collection site was 15 cm from the placenta on the umbilical cord, and the umbilical cord collection site was disinfected with 75% alcohol and then fixed with sterile gauze to prevent slipping. When performing umbilical vein puncture, the tip of the blood collection needle was inclined downward or laterally. The needle moved along the vascular wall 1 to 2 cm after the blood was observed. When the UCB flowed into the blood bag, the bag was gently shaken to allow the anticoagulant to fully mix. The UCB was collected until the cord turned gray and UCB collection was completed. Another needle was used to collect the UCB for blood gas analysis. The procedure was as follows: 12,500 units of heparin was dissolved in 0.9 % saline 100m, and after draining 1 ml of the wetting injector with a 2 ml syringe, the liquid with heparin was pushed out. Approximately 2–4 mL of umbilical cord vein blood was collected from the umbilical cord between the first and second forceps. After collection, the samples were immediately sealed and sent for blood gas analyses. The UCB collection method is shown in Figure UCB double collection method. (A) Clamping the umbilical cord with the first hemostatic clamp and cutting off. (B) Clamping 3–4 cm away from the first hemostatic clamp by another hemostatic clamp. (C) Collecting UCB for separating hematopoietic stem cells. (D) Collecting UCB for blood gas analysis. UCB = umbilical cord blood.Group B: Collection of UCB for separating hematopoietic stem cells. The procedure was the same as that in group A.Group C: Collection of UCB only for detecting blood gas. The procedure was the same as that used for group A.After collecting the UCB for separating hematopoietic stem cells, it was immediately stored in a refrigerator at 0 to 4°C and transported to the GDCBB within 24 hours.