- Key People:
- Charles Richard Drew
- Karl Ferdinand von GrƤfe
- On the Web:
- Johns Hopkins Medicine - Blood Transfusions in Adults (Nov. 04, 2026)
blood transfusion
What is the purpose of blood transfusions?
How is blood collected and prepared for transfusion?
When was the first blood transfusion performed?
What are blood substitutes?
blood transfusion, the transfer of blood into the vein of a human or animal recipient. The blood either is taken directly from a donor or is obtained from a blood bank. Blood transfusions are a therapeutic measure used to restore blood or plasma volume after extensive hemorrhage, burns, or trauma; to increase the number and concentration of red blood cells in persons with anemia in order to improve the oxygen-carrying capacity of their blood; and to treat shock. Transfusions are a crucial adjunct in some types of surgery in which patients lose large amounts of whole blood that must be replaced.
Transfusion procedures and blood storage
The procedure for transfusing blood is relatively straightforward. Blood is collected from a donor by means of a sterile needle and is passed into a specialized plastic collection bag containing anticoagulants such as sodium citrate to prevent clotting. The blood is then tested for infectious agents and often is separated into components such as red blood cells, plasma, and platelets. During transfusion, compatible blood products are delivered through sterile tubing into a vein in the recipientās arm, either by gravity or with infusion devices that regulate flow. The procedure is accomplished slowly, often taking anywhere from one to four hours to complete. The use of sterile containers, tubing, and needles helps ensure that transfused or stored blood is not exposed to disease-causing microorganisms. Blood can be kept in a state satisfactory for use in transfusion by the addition of special preservatives and refrigeration.
Methods of fractionating the blood have allowed its use in specialized forms:
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- Whole blood, used in some cases of severe acute blood loss or trauma.
- Packed red blood cells (erythrocytes), used to treat anemia and to restore oxygen-carrying capacity.
- Washed red cells, used for patients with severe allergic transfusion reactions.
- Plasma and fresh-frozen plasma, used to replace clotting factors in patients with bleeding disorders, liver disease, or massive transfusion.
- Recombinant clotting factor concentrates (genetically engineered replacements) used to treat hemophilia and other coagulation disorders.
- Albumin, derived from plasma, used in selected cases involving shock, burns, or severe fluid imbalance.
- Immune globulin, concentrated antibodies used to provide protection against certain infections or immune-related conditions.
- Fibrinogen concentrates, used to treat bleeding caused by fibrinogen deficiency.
Exchange transfusion is a procedure in which much or all of a patientās blood is gradually removed and replaced with donor blood. It is used for specialized clinical situations, particularly severe cases of hemolytic disease of the newborn (erythroblastosis fetalis), and certain poisonings or disorders involving dysfunctional blood components..
Developments in transfusion therapy
Blood typing
The first documented records of intravenous blood transfusions date from Europe about the mid-17th century, but many patients died because physicians did not yet understand blood incompatibility. As a result, the practice was widely restricted in countries such as France, England, and Italy. Blood transfusion did not become a reliable and lifesaving medical procedure until the discovery of blood group antigens and antibodies. The first system to be identified was the ABO blood group system in 1901. In 1940 a second major system, called the Rh (Rhesus) blood group system, was identified. These discoveries made it possible to match donor and recipient blood types more safely, greatly reducing dangerous transfusion reactions and laying the foundation for modern transfusion medicine.
Screening for pathogens
In the 1970s it was discovered that blood transfusions presented a significant risk for the transmission of life-threatening viruses. During the 1970s and early 1980s, testing of donors for infectious markers of hepatitis B virus (HBV), such as hepatitis B surface antigen (HBsAg) and an antibody to the so-called core antigen (anti-HBc), greatly reduced the risk of HBV transmission. Shortly thereafter another transfusion-transmitted virus, hepatitis C virus (HCV), was identified as the principal agent of what was then known as non-A, non-B hepatitis. People infected with HCV produce an antibody known as anti-HCV, which can be detected in screening tests. Since 1998 it has been possible to screen for the presence of HCV nucleic acids using polymerase chain reaction (PCR) technology. PCR is a molecular technique that amplifies specific DNA or RNA sequences, allowing for the detection of viral genetic material even at very low concentrations. This molecular detection system can identify HCV in donors before they have produced antibodies, and its use in effective screening programs has greatly reduced the risk of transfusion-transmitted HCV.
Similar progress was made in testing donors for evidence of human immunodeficiency virus (HIV). In the early 1980s, when it was realized that HIV, which gives rise to acquired immunodeficiency syndrome (AIDS), could be transmitted via blood transfusion, concern about the safety of transfusion increased significantly. Today, blood donors are routinely screened for HIV using tests that detect antibodies, viral antigens such as p24, and viral nucleic acids. Combined with donor health questionnaires and additional screening procedures, these measures have made the risk of HIV transmission through blood transfusion extremely low.
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In the 1980s other viruses were also discovered in blood used for transfusions. For example, cytomegalovirus (CMV), a large deoxyribonucleic acid (DNA) virus, is harbored within white blood cells (leukocytes) in about 50 to 60 percent of healthy blood donors. In general, CMV is not a threat to transfusion recipients unless their immune systems are suppressed. The risk of CMV transmission has been dramatically reduced by screening donors for the antibody to CMV, as well as by leukoreduction using special filters to remove leukocytes from blood components. Two other virusesāhuman T-cell lymphotropic viruses I and II (HTLV-I and HTLV-II), which are in the same family of retroviruses as HIVāare similar to CMV in that they appear to be strictly white-cell-associated. Tests developed in the late 1980s enabled screening for serum antibodies to HTLV-I/II and, along with leukoreduction, have greatly reduced the risk of HTLV-I/II transmission.
In addition to the risk of viral transmission, other infectious agents may be transfusion-transmitted. For example, there is some risk of bacterial contamination in blood components. This is especially true of platelet components, which are stored at room temperature. Bacterial contamination, although extremely rare, can cause fever, shock, and death if not recognized and treated early. The use of solvents and detergents to treat plasma has virtually eliminated the risk of HBV, HCV, HIV, and HTLV-I/II transmission via transfusion. This solvent detergent treatment process, which is approved and licensed by the U.S. Food and Drug Administration (FDA), has been made readily available to blood centers. However, solvent detergent treatment does not work for all blood components, including whole blood, red blood cells, and platelet concentrates, since this treatment can destroy vital cellular constituents. Scientists are working to develop safe additives capable of neutralizing or killing viruses and bacteria.