Last Review Date: July 1, 2018
Blood banking, the process of collecting, testing, processing, and storing blood for later use, is a cornerstone of emergency and surgical medicine and is dependent on the clinical laboratory for ensuring the safe use of blood and its components.
This article provides a glimpse into five key aspects of blood banking:
- donating blood
- protecting the blood supply
- ensuring its proper use
- risks involved for donors as well as recipients
The Australian Red Cross Blood Service is a branch of the Australian Red Cross and the national organisation responsible for the provision of quality blood products, tissues and related services to the Australian community.
- 27,000 donations are needed every week of the year to ensure that the Australian community has the blood and blood products it needs
- Over half a million Australians donate blood, on average, around twice each year
- 34% of donated blood helps patients with cancer and blood diseases, 19% other causes of anaemia, 18% surgical patients including open heart surgery and burns, 13% other medical problems including heart, stomach and kidney disease, 10% orthopaedic patients including fractures and joint replacements, 4% obstetrics including pregnant women, new mothers and young children and 2% to trauma including road accidents.
All of Australia's blood donors are voluntary and unpaid. Australia is also one of a handful of countries which is self-sufficient in the supply of fresh blood and most blood components. Another factor that contributes to Australia having one of the safest blood supply systems in the world are the regulations by which eligibility to give blood is determined.
There are a range of reasons why anyone could be 'temporarily deferred' or 'permanently deferred' from giving blood, including age, recent short-term illness, medical history, pregnancy status and lifestyle issues.
Every time you give blood, the Blood Service is required to verify your identity and ensure you complete a detailed and confidential questionnaire, to make sure that the blood you are kindly and generously giving fulfils the eligibility criteria. This ensures it is as safe as possible for you, the donor, as well as for the recipients.
Donors must be:
- 18 - 70 years of age (in Queensland and WA, state legislation requires donors who are 16 or 17 to have parental consent)
- are fit and healthy at the time of donation and in the previous seven days
- weigh at least 45 kg
- have a Hb level of between 120 and 165 g/L for females and between 130 and 185 g/L for males, and
- pass a physical and health history examination prior to donation
The physical checks include measurement of weight, blood pressure, pulse, and temperature as well as a test for anaemia, which requires just a few drops of blood from your finger.
To protect the health of both the donor and the recipient, the health history questionnaire asks about potential exposure to transfusion-transmissible diseases, such as viruses like HIV, hepatitis B and C, as well as parasites that cause diseases such as malaria.
Certain people are not permitted to donate blood to protect the health of the donor or recipient. Some of these include:
- Anyone who has ever injected or been injected illegal or body building drugs
- Men who have had sexual contact with other men
- Anyone with a positive test for HIV, or anyone who thinks they might be HIV positive
- Men and women who have engaged in sex for money or drugs
- Anyone who has had hepatitis B, or C virus
- Anyone who has had a blood transfusion in the past 12 months
- Anyone who has had acupuncture, body piercing or a tattoo in the last 6 months
- Anyone who has been pregnant in the past 9 months
There also may be some restrictions if you are taking certain medications at the time of donation. You may be ineligible to donate or deferred for a period of time. There are also varying deferral periods if you have been vaccinated recently. For more details visit the Australian Red Cross Blood Service website.
Donors have a personal responsibility to help ensure the safety of the blood supply. You should express any concerns or questions you may have about past illnesses you had or may have been exposed to before donating. Who knows? Maybe someone close to you will be the recipient of your blood donation.
Where can blood be donated?
Blood can be donated at blood collection centres, or mobile sites temporarily set up in public areas such as colleges, workplaces, and churches. For more information on donating or receiving blood, visit the Blood Service website or phone 13 14 95.
What is donated and how often?
Usually one unit of 470 ml of blood is collected into a blood bag from a vein in the inner part of the elbow joint using a new, sterile needle and blood collection set. This donation is less than 10% of your total blood volume. Your body replenishes the fluid lost during donation in 24 hours, but it may take up to 2 months to replace the lost red blood cells. Therefore blood can usually be donated only once every 3 months.
What are the components of blood?
Blood is made up of several components which can be separated. These individual components mean multiple patients, each with different clinical needs, can benefit from a single blood donation of whole blood. The different components include:
Red blood cells
Red blood cells are the carriers of haemoglobin, which is a protein needed to transport oxygen around the body. You may be given red blood cells if your haemoglobin level or red blood cell count are low, or if you have lost a lot of blood from an injury or during surgery.
Platelets are pieces of cells that help to stop bleeding by sticking together to form a plug. Some people have low numbers of platelets. This may be caused by disease, certain medications (such as chemotherapy) or treatments (such as radiation therapy). Platelets are given to prevent or control bleeding in these people.
Fresh frozen plasma and cryoprecipitate
Fresh frozen plasma and cryoprecipitate, which are produced from fresh frozen plasma, contain clotting factors which work with platelets to seal wounds. If any of the clotting factors are not present in the blood, bleeding can occur very easily and is difficult to control. You may be given plasma products if your blood is not clotting properly.
Separation of these components is performed by the Blood Service in blood processing centres. A whole blood donation is centrifuged which causes the various components to form layers with the red blood cells at the bottom, white blood cells and platelets (also known as 'buffy coat') in the middle and finally plasma at the top.
The plasma is then removed into another sterile blood bag and further processed to separate cryoprecipitate containing fibrinogen and other clotting factors. Plasma from several donors may also be pooled and processed further (fractionated) to provide purified plasma proteins, such as albumin, immunoglobulins and clotting factor concentrates.
The 'buffy coat' layer with platelets and white cells is also transferred into a new bag for additional processing. The 'buffy coats' from four donors are pooled together and treated to remove the white blood cells. The remaining platelets are re-suspended in a special nutrient solution for subsequent transfusion.
What is autologous blood donation?
Another type of blood donation is autologous donation. This refers to transfusions where the blood donor is the recipient of their own donated blood and normally a patient wanting their own blood for use in a planned surgical procedure. There are many reasons why someone may want to receive a transfusion of their own blood but autologous blood donation is not normally recommended. Although it may reduce the likelihood of needing another donor’s (or allogeneic) blood it increases the overall risk of needing a blood transfusion. Autologous blood donation is therefore only recommended for exceptional circumstances such as a patient with a rare blood group or multiple red cell antibodies where it can be difficult to find compatible donors.
A person can donate their blood up until 72 hours prior to their surgery, which allows time for the body to replenish its blood supply. Iron supplements or erythropoietin also may be prescribed to help increase the person's red blood cell count. Any blood that remains unused during the surgery is discarded.The decision should be made together by the patient and his or her doctor. Other options may be preferred, such as intra-operative blood salvage, in which any blood lost during the surgery can be collected and returned to the patient's body.
Testing donated blood
Blood donations are tested in order to:
- Allow appropriate selection of blood for transfusion. For example, to ensure ABO compatibility between donor and recipient
- Minimise or prevent (where possible) adverse consequences of transfusion. For example, to minimise the risk of transmission of infections which can cause disease in transfusion recipients
- Identify donors whose donations are not suitable for transfusion- for example, donors found to carry transfusion-transmissible infections must be notified and counselled.
In Australia, all donations are tested for:
Testing and checking of results occurs before blood components are released for clinical use or further manufacture. If any of the mandatory infectious disease screening tests is confirmed reactive, the donation is destroyed. Only donations that have satisfactory results for the above tests and meet other defined specifications are released for transfusion.
All tests are performed in licensed facilities, according to the principles of good laboratory and manufacturing practice (GLP/GMP), the manufacturer's instructions and strict Blood Service guidelines and standard operating procedures.
Storing Blood safely
Proper storage of whole blood and blood components is essential.
- Red blood cells must be stored under refrigeration (between 2°C and 6°C) and can be kept for a maximum of 42 days. In special circumstances e.g. rare blood types, or for special patients red blood cells may be stored frozen for up to 10 years
- Platelets are stored at room temperature (between 20°C and 24°C) for a maximum of 5 days
- Fresh frozen plasma is stored frozen (at -30°C or below) for a maximum of 1 year
- Cryoprecipitate, made from fresh frozen plasma, is stored frozen (at -30°C or below) for a maximum of 1 year
Blood typing involves testing a person’s blood for the presence or absence of certain chemical structures called antigens that are present on the surface of red blood cells. Two of these antigens, are the A and B markers used in ABO typing.
People whose red blood cells have A antigens are considered to be blood type A; those with B antigens are type B; those with both A and B antigens are type AB; and those who do not have either of these markers are considered to have blood type O, which is the most common in the Australian population.
Our bodies produce antibodies against those ABO antigens we do not have on our red blood cells, which is why we can only receive blood from donors with 'compatible' blood types.
Another important surface antigen is called RhD or the 'D' antigen. If it is present on your red blood cells, your blood type is Rh-positive; if it is absent, your blood type is Rh-negative.
ABO and RhD blood typing are performed on all donor units collected by the Blood Service and also in the transfusion laboratory for hospital patients. There are two steps to ABO typing: known as 'forward' and 'reverse' typing.
First, forward typing is performed by mixing a sample of blood with a commercial anti-A reagent (that contains antibodies against type A blood) and with anti-B reagent (that contains antibodies against type B blood). Whether the blood cells stick together (agglutinate) in the presence of either of these reagents determines the blood type.
Second, in reverse typing, the patient’s plasma is mixed with blood cells of known A or B types to look for agglutination. A person’s blood type is confirmed by the agreement of these two tests.
Similarly, with RhD typing a sample of a person’s red blood cells is mixed with a commercially-prepared reagent containing D antibodies. If agglutination occurs, then the blood is Rh-positive; if no reaction is observed, then the blood is Rh-negative.
RhD testing is especially important during pregnancy because a mother and her fetus could be incompatible. If the mother is Rh-negative but the father is Rh-positive, the fetus may be positive for the D antigen. As a result, the mother’s body could develop anti-D antibodies which can destroy the baby’s red blood cells.
To prevent development of anti-D antibodies, an Rh-negative mother is treated with an injection of RhD immunoglobulin during the pregnancy and again after delivery if the baby is Rh-positive.
Compatibility testing is performed to determine if a particular unit of blood can be transfused safely into the intended patient. This includes ABO- and RhD blood typing (see above), antibody screening (for unexpected red blood cell antibodies that could cause problems in the recipient), and cross-matching.
There are many antigens besides A, B, and D. However, neither the donor nor the recipient is tested routinely for these other antigens. But, if a patient has had a previous transfusion or been through a pregnancy, they may have developed antibodies to one of these other antigens. Therefore, it will be important in all future transfusions that the donor’s red blood cells do not have that particular antigen; otherwise, the recipient may have a transfusion reaction.
The presence of such an antibody is determined by doing an antibody screening test by mixing the patient’s plasma with red cells having a known antigenic makeup.
Antibody screening is performed to determine if the patient has antibodies that might react with the donor’s cells. If an antibody is found, the laboratory staff will investigate further to identify the specificity of the antibody and locate donor units that lack the antigen that matches the patient’s antibody. This unit will then be tested to confirm that this is a safe match.
It is ideal to receive a blood transfusion with blood that matches your blood type exactly. However, anyone can receive type O red blood cells in an emergency. Therefore, people with type O blood (particularly O Rh-negative) are called “universal donors.”
People with type AB Rh-positive blood can be transfused with red blood cells from individuals of any ABO type and are commonly referred to as “universal recipients.”
Positive patient identification - confirming your identity before a blood test - helps to keep you safe.
For all blood tests it is very important that your identity is confirmed before someone takes the blood sample. Directly after the blood test is taken, the blood sample should be labelled, by the collector, with your correct details (including your full name and date of birth) and this must be done before the sample collector leaves you.
Inadvertently mixing up your blood sample with another person’s, or incorrectly labelling a pre-transfusion blood sample, can lead to the wrong blood product being given to you, which can have fatal consequences.
Before the blood sample for testing is taken it is very important that the person collecting the sample asks you to state and/or spell your full names and date of birth. This is to confirm that you are the right person to take the blood sample from and is the first step to ensuring your safety. If you are accompanying someone who is unable to confirm their identity, such as a child or someone who is incapacitated, then you should be asked to confirm their identity and be asked to provide their correct details. In a hospital setting your identity band will also be checked to ensure they have selected the right person.
Once your blood sample has been obtained the collector may repeat your details back to you as they write on the blood sample label and/or, hand you the labelled blood sample tube for you to check that your date of birth is correct and your names are spelt correctly. This is another way of checking the blood sample tube is labelled correctly and to ensure your safety.
If your blood sample has been labelled incorrectly another blood test will have to be taken. Most laboratories will not accept incorrectly labelled blood samples or samples where the labelling has been altered in any way for transfusion tests. This is to ensure your safety.
Have you been asked for your full name and date of birth?
Remember this is to keep you safe before every blood test.
Are there risks associated with donating or receiving blood? The blood banking community can assure the Australian public that it is safe to donate blood. A new, sterile needle and blood collection set is used for each donation procedure. Therefore, you cannot get infected with viruses, such as HIV or hepatitis, by donating blood.
In addition, donors are screened before giving blood to ensure that they are in good health and have no complications that could cause them harm by donating. Mild side-effects from the procedure that a donor might experience include stinging during insertion of the needle, upset stomach, dizziness, and possibly a small amount of bruising appearing later around where the blood was taken. In very rare cases, a donor may faint, have muscle spasms, or suffer nerve damage.
There are some risks with receiving blood transfusions. Some people fear that they may contract an infectious disease. However, donated blood is carefully screened for transmittable diseases, as noted earlier in this article. The Blood Service publishes figures for the risk of infection from transfusion which are updated each year. The risk is now extremely low (about 1 in 2 million units transfused for hepatitis C, HTLV, HIV and slightly greater at 1 in 300,000 for hepatitis B [2014 figures]). Of greater concern is ABO incompatibility and transfusion reactions.
ABO incompatibility occurs when a patient receives donor blood with a different and incompatible blood group to their own; for example a group O patient receiving group A, or group B blood. The recipient of the blood transfusion could have an immune reaction against the foreign blood cells that can be very dangerous, even life-threatening.
Besides ABO incompatibility, there are other incompatibilities that can cause transfusion reactions. Antigens occur on other blood components, including white blood cells, platelets, and plasma proteins. The immune system will attack and destroy the donated blood cells, with serious side-effects for the patient.
There are several types of transfusion reactions, such as allergic and febrile (characterized by fever). Treatment will depend on the type of reaction and the patient’s symptoms (for example, antihistamines may be used to reduce rash and itching from allergic reactions while paracetamol may be prescribed to reduce fever).
Many transfusion reactions go undetected and, therefore, unreported. However, the reported rate of transfusion reactions is on the order of 1 per 1,000 components or 1 in 400 people. Nearly all of these are non-infectious complications and include volume overload, and febrile or allergic reactions.
Australian Red Cross Blood Service
Blood Service: Blood products and transfusion practice for health professionals
Bloodsafe eLearning Australia