Blood brings oxygen and nutrients to all the parts of the body so they can keep working. Blood carries carbon dioxide and other waste materials to the lungs, kidneys, and digestive system to be removed from the body. Blood also fights infections and carries hormones around the body.

In many situations, blood transfusion has been important. blood is usually transfused to replace red blood cells that carry oxygen in various situation necessitate transfusion blood loss due to bleeding, surgery or a medical procedure medical conditions that prevent the body from producing new blood cells medical conditions such as anaemia, kidney disease, cancer, leukaemia, chemotherapy, chronic disease may prevent the production of new blood cells. Transfusion may be necessary until the body is able to produce its own blood cells.