About a Cord Blood Bank Umbilical cord blood is human blood from the placenta and umbilical cord that is rich in hematopoietic stem cells. Cord blood is collected after the umbilical cord has been detached from the newborn, and utilized as a source of stem cells for transplantation. A Cord blood bank is a cache or bank of Cord blood or Cord blood components, gathered as a result of Cord blood donation, stored and preserved for later use in blood transfusions.