Blood transfusions may be required for various medical conditions and are given when your body requires more blood cells.
A blood transfusion contains mostly red blood cells and a liquid called plasma. The effects of a blood transfusion are only temporary as red blood cells survive for an average of 120 days, and need to be replaced.
Red blood cells
Red blood cells carry oxygen to the organs of the body by binding it to an iron containing protein called haemoglobin (Hb). In adults, normal Hb levels are 130-180g/L for males, and 120-160g/L for females. Red blood cells give blood its red colour and your skin its pink colour.
The percentage of red blood cells in your blood is called the haematocrit (Hct).
Anaemia is a low red cell count or haemoglobin (Hb) and is common in many of the blood cancers or as a result of treatment. Signs of anaemia include fatigue, shortness of breath and pale skin.
Why people may need a blood transfusion
A blood transfusion may be given to correct the effects of anaemia symptoms and to improve healing and a person’s sense of wellbeing.
Where blood transfusions come from
People usually receive blood from anonymous blood donors. One blood donation generally gives three blood products – red blood cells, plasma and platelets. In Australia, every blood donation is tested for a variety of bacteria and viruses including human immunodeficiency virus (HIV), hepatitis and human T-lymphotropic virus type I (HTLV-1).
Receiving a blood product transfusion
Before accepting a blood product transfusion, it is important your doctor explains both the benefits and the risks to you. You may be required to sign a consent form.
Your doctor prescribes the appropriate blood product for you on your medication chart, and states the time it will take to be administered by nursing staff. Your blood is then cross-matched in a laboratory (see next section) and the blood product is issued from the hospital, day centre pathology or blood bank.
Two nurses will check the blood in your presence, to ensure you are the correct person to receive the product being checked, and that all details are accurate, including your blood type. A blood transfusion usually takes 1-4 hours to infuse.
Cross-matching is a process where a small sample of blood is taken from an intended blood product recipient (usually from a vein in their arm) then sent to a laboratory to determine compatibility with available donor blood (i.e., the blood that is in the blood bank).
The red cell blood group (known as ABO and RH types) and other antigens (cell markers) on the recipient’s red cells need to be determined and the recipient’s antibodies to the donor’s red cells are checked. This is known as a ‘group and screen’ or a ‘group and hold’.
The cross-match process is important, as a mismatch of blood can be life threatening. When a match is found between the recipient and donor blood types, the donated blood is labelled with the details of the recipient and is ready to be transfused to the patient. Usually, a cross-match is only accurate for 72 hours, then the process needs to be carried out again if blood is still required.