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How much blood and stem cells does a typical umbilical cord hold?
The median size of cord blood collections in family banks is 60mL or 2 ounces. That small volume of blood corresponds to 470 million Total Nucleated Cells (TNC) or 1.8 million cells that test positive for the stem cell marker CD34. Thus, most healthy full-term babies have over a million blood-forming stem cells in their umbilical cord blood. By comparison, most public cord blood banks will only keep collections that are much bigger than average, and throw out the donations that are below a threshold of a billion TNC, corresponding to a blood volume of about 100 mL or 3 ounces.
Sun, JJ et al., Transfusion Sept. 2010; 50(9):1980-1987 doi:10.1111/j.1537-2995.2010.02720.x