MODEL RELEASED. Issuing blood units. Laboratory technician using a barcode scanner to register the issuing of donor blood. The blood will have been through a process of separation and mixing of its component parts to optimize its use. It will have been dated and labelled with its blood group and other properties. Barcodes track the blood through the whole process and careful records are kept in case of infection or other complications. Blood is used to treat various blood disorders and to treat blood loss during surgery or after an accident.