Blood transfusion is the process of transferring blood or any of its products into a person’s circulation via intravenous route. In modern medicine, only components of the blood are usually transfused. Such components include white blood cells, red blood cells, plasma, platelets, and clotting factors.


  • Red blood cells contain hemoglobin and are part of the immune system. They are known as oxygen-carriers.
  • White blood cells are known as the body’s soldiers but are not commonly used during transfusion.
  • Plasma acts as a buffer, and contains proteins and other important substances needed for the body’s overall health.
  • Platelets are involved in blood clotting, by helping the body to arrest bleeding.


Prior to blood transfusion, there are steps that need to be taken to ensure that the quality, safety and compatibility of the blood product are sustained. Most countries have specific and individual legislation that guides the safety and quality of blood transfusion. These procedures are to be followed keenly in order to enable investigation and management of any transfusion reaction or suspected transfusion-related disease transmission.

  • Blood donation

Blood transfusions use two sources. It can either be autologous or homologous. i.e. either one’s own blood or another person’s blood. Homologous transfusion is much more common and it starts with donation of blood. The blood is collected as whole blood via intravenous route and mixed with an anticoagulant.


After donation, the donated blood is then subjected to various tests in order to make sure that it is suitable for use in specific patient populations. If the collected blood passes all tests, it is then separated into different blood components (red blood cells, plasma, platelets, albumin protein, clotting factor concentrates, cryoprecipitate, fibrinogen concentrate, and immunoglobulin) by the method of centrifugation.

  • Compatibility testing

This step is also known as typing and cross-matching of donor and recipient blood. This has to be done before a recipient receives a transfusion.

In emergency situations where crossmatching may not be feasible, and the risk of decreasing hemoglobin outweighs the risk of transfusing uncrossmatched blood, O-negative blood is usually transfused. This is followed by a crossmatch immediately or as soon as possible. O-negative is also used for children and women of childbearing age. It is preferable for the laboratory to obtain a pre-transfusion sample in these cases so a type and screen can be performed to determine the actual blood group of the patient and to check for alloantibodies.


Blood transfusion reactions can range from mild to severe. Always report even mild side effects to the doctor or nurse immediately you notice it. Certain medications can be administered prior to blood transfusion to reduce side effects.

Examples of mild blood transfusion reaction include:

  1. Chills
  2. Wheezing
  3. Fever
  4. Chest or muscle pain
  5. Headache
  6. Swelling

Examples of serious adverse transfusion reaction include:

  1. Iron overload
  2. Immunologic reactions such as increased heart rate, shortness of breath, and rapid drop in blood pressure
  3. Febrile nonhemolytic reactions
  4. Allergic transfusion reactions such as itching
  5. Anaphylactic reactions such as wheezing, shortness of breath, and circulatory shock
  6. Transfusion-related acute lung injury
  7. Transfusion-associated circulatory overload
  8. Infections

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