Blood transfusions, routine, fairly safe and sometimes taken-for-granted lifesaving procedures, were not medical options until the early 20th century when the major blood groups were discovered and carefully studied.
Blood from transfusions is used to stabilise a condition or to save the lives of people who have been in accidents or need surgery for other reasons. It is also used for people with cancer, haemophilia, leukaemia or other bleeding disorders. The Australian Red Cross Blood Service estimates that more than one million donations of blood are needed every year to maintain the blood supply.
Nowadays, whole blood is rarely used except in cases of sudden and severe blood loss. Instead, it is nearly always separated into its individual components and used for different purposes. Red blood cells are used for treating types of anaemia that can’t be helped by other medical treatments and for giving ‘top-ups’ to people after surgery or childbirth. Platelets, the component of blood that helps control bleeding, are given to people with cancer or leukaemia after they have had chemotherapy or a bone marrow transplant. Plasma, the clear fluid in blood, is often used to help people whose blood does not clot properly, such as can occur if someone has had anticoagulant treatment or suffers from liver disease or haemophilia.
There are many safeguards in place to ensure safe blood for people who need it. Firstly, blood is donated by volunteer donors who must attend a personal interview every time they donate, and answer detailed questions about their health and previous and current medical conditions. Only people who meet the Red Cross Blood Service’s guidelines can give blood. Then, every sample of blood given by donors is tested for HIV, hepatitis, syphilis and other serious communicable diseases.
Blood is classified into groups or types depending on the chemicals (called antigens) found on the surface of the red blood cells. There are two types of antigens, known as A and B. Depending on whether a person’s blood contains one or the other antigen, both, or neither, it is classified as A, B, AB or O respectively. These fall into what is known as the ABO system.
Blood is further categorised by the rhesus (Rh) system in which a person’s blood is classified according to whether or not their blood contains the Rh antigen. Using these 2 systems together a person’s blood will be one of 8 possible types (O+, O-, A+, A-, B+, B-, AB+, AB-).
Before a transfusion is performed, blood is ‘cross-matched’ to ensure the donor's blood is compatible with the recipient's blood. A person cannot safely be transfused with blood of a group containing antigens to which he or she has antibodies. For example, if a patient with type A blood (whose plasma contains anti-B antibodies) is transfused with blood from a type B donor (whose red blood cells have antigen B), a transfusion reaction will occur, which is triggered by the body’s response to a foreign substance.
This reaction can produce fever, chills, itching, or aches and pains. In more serious cases it causes haemolysis (blood cell destruction) that results in shortness of breath, severe headache, chest or back pains and blood in the urine.
Generally, people who need blood transfusions receive blood of the same type, but some blood groups are compatible with others. For example, in an emergency anyone can receive type O negative blood, and people with type AB positive blood can receive blood of any ABO type. Therefore, people with type O negative blood are known as ‘universal donors’ while those with type AB positive blood are known as ‘universal recipients’.
If a blood transfusion is indicated during medical treatment, the risk of not receiving it far outweighs the small risk from the transfusion, which mainly relates to the remote possibility of receiving blood of an incompatible type. The risk of receiving a communicable disease from blood is considered negligible, particularly with rigorous screening of donors and the introduction of a new, and more accurate, testing method for HIV and hepatitis C in July 2000.
People who are expecting surgery and who do not wish to receive donated blood can make arrangements to be their own blood donor. In this procedure, your own blood is collected and stored ready for use during the surgery. In some cases people can also arrange for a friend or relative to donate blood for them. You should discuss this with your doctor if you would like more information.
People aged between 16 and 70 years who are in good health and meet the Red Cross Blood Service’s guidelines can become a blood donor. If you are aged 16 or 17 and live in Victoria, Queensland or Western Australia, you will need parental consent to give blood. If you are interested, you should call the Red Cross Blood Service on 13 14 95 for further information and the location of your nearest donation centre.
Last Reviewed: 02 May 2009