Tests On Your Blood
Donating blood is simple
Component
donation
Donor
Award Scheme
FAQs
More information
Tests
On Your Blood
You may have
noticed that each time you give blood we take blood samples as well as
the donation. These samples are used to complete our safety tests back
in the laboratory. These safety tests are mandatory, in other words we
carry them out on every single blood donation we receive, whether this
is your first donation or just one of the many you have given over the
years. These tests are also done if you give blood samples for supplementary
testing (e.g. for T-cruzi - see below).
These tests play a very important role in ensuring we provide a safe blood
supply to patients, as they test for your blood group, and for infections
that can be passed from donor to patient via a blood transfusion. The
tests are carried out, mainly by computer controlled, automated machines,
which can test many samples at once, both quickly and easily, so helping
us to get donations to the hospitals as fast as we can. Any donation that
has not passed these safety tests cannot be used.
If we get a positive test result we will inform you and offer you appropriate advice. If the result is significant to your health you will be asked to discuss the results with one of our doctors and, with yourpermission, we will arrange a referral to your own doctor or a specialist.
Very occasionally these tests are not done. For instance if you give an
incomplete blood donation and no blood samples are obtained, or if you
are anaemic and we take a sample only to check your 'iron level'.
As well as checking your blood group, we test for the following:
Syphilis: Syphilis is caused by an organism called Treponema pallidum. This organism belongs to a family of infectious agents which cause yaws and pinta as well as syphilis. Syphilis is usually a sexually transmitted infection which, if untreated, can cause serious disease. Yaws and pinta are tropical diseases which cause skin and joint problems. All three diseases are fully treatable with penicillin and most people who have had these diseases have been treated.
The tests we use look for antibodies, which can often be found in a person’s blood long after the infection has gone. A positive test for syphilis usually relates to an infection in the past, but if the test is positive we are not able to use your blood.
Hepatitis
B virus (HBV):
This is a virus which infects the liver. It can cause inflammation of
the liver (hepatitis) and liver damage. Hepatitis B is very common in
some parts of the world where it is often transmitted from mother to child
at birth or in infancy. Most donors we identify have an association with
those places and appear to have been infected since childhood or early
life.
Our test looks for a substance called hepatitis B surface antigen, which is part of the ‘coat’ of the virus. If we find this substance in a donor’s blood then further tests are performed to confirm the result. Most of the donors we identify are long - term carriers of the virus who feel completely well. Acute hepatitis B infection is uncommon in blood donors. Occasionally we get a positive result because the donor has recently had an immunisation against hepatitis B and not because infection is present.
Human
immunodeficiency virus (HIV):
This virus causes Acquired Immune Deficiency Syndrome (AIDS). Once an
individual becomes infected with HIV then the virus remains in the body
and eventually causes destruction of the immune system. It is mainly transmitted
sexually, or from mother to baby, or by intravenous drug use. A person
who has HIV does not necessarily have AIDS.
Our test looks for antibodies to the virus, but unlike many other infections the presence of the
antibody shows that the virus is present, and not that the infection is in the past.
Hepatitis
C virus (HCV):
This virus infects the liver and can cause inflammation and liver damage.
It is commonly transmitted by intravenous drug use. We have two kinds
of test; a test for antibodies and a test for the virus. The test for
virus is an extra safety test and can tell us whether a donor with antibodies
is infected or not. Most of the donors we identify are long-term carriers
of the virus who feel completely well.
Human
T-lymphotropic virus (HTLV):
This virus infects white cells called T-lymphocytes, and can cause a neurological
disorder called Tropical Spastic Paraparesis (or HTLV Associated Myelopathy)
and Adult T cell Leukaemia. It is relatively common in some populations
and is thought to be transmitted mainly from mother to child at birth
and by breast feeding.
The test is for antibodies and a positive test means the individual is infected with the virus. Comparatively few infected individuals become illand most carriers feel completely well.
SUPPLEMENTARY TESTS
These tests are not performed on every donation. Whether or not we test
depends on the donor's individual circumstances, in particular with reference
to travel. Supplementary tests are also done to provide specifically tested
blood for particular types of patient.
Malaria: Malaria is caused by a parasitic infection transmitted by the bites of Anopheles mosquitoes. The infection causes fever and is a major cause of death in some parts of the world. The test is for antibodies to the malaria parasite. A positive result does not necessarily mean that the individual has active malaria, merely that they have had malaria at some time in the past. The antibodies can disappear over time, so donors with a positive malaria antibody test are not necessarily unable to give blood in the future.
T-cruzi: This is a parasite called Trypanosoma cruzi. The parasite is found in certain parts of Central and South America and is transmitted to humans by biting insects or from mother to baby at the time of birth. Long-term carriers of the parasite are at risk of illness (also called Chagas Disease), due to destruction of the muscles in the heart and intestines. Not all carriers become ill.
Our tests look for
antibodies, to the infection. A donor's place of birth and travel history
determines whether the test is required.
Cytomegalovirus (CMV): This is a very common virus which causes a mild ‘flu-like’ illness. Individuals in good health make a full recovery and are usually unaware of having been ill. We test for antibodies and a positive test indicates that the individual has had CMV infection and may still be carrying the virus. Having antibodies to CMV is of no significance to the health of the donor.
For those patients with a poor immune system, (bone marrow recipients or small babies) the presence of CMV in the blood given to them can cause a life-threatening illness. However, CMV positive blood is safe to give to other patients not at risk, so donors are not informed of a positive result.
West Nile Virus (WNV): Despite its name, this virus only affects you giving blood if you travel to Canada or the USA and only in the summer. The virus is transmitted to humans by mosquito bites. It causes an acute infection that can occasionally affect the brain (encephalitis or inflammation of the brain). However, sometimes it is not noticeable at all. Only a small number people who catch WNV become ill and no cases have been found yet in the UK.
Our test looks for the infection. We expect very few donors will be found to have the virus. Anyone who has had WNV can continue to give blood once they have recovered.
Skin-piercing: Until recently if you had had skinpiercing of any kind, you had to wait 12 months before giving blood. We have now introduced an extra supplementary test that means that we can now take donations 6 months after skin-piercing.
The test looks for evidence of past hepatitis B infection. Donors with positive test results will probably have to stop donating. If you fall into this group we will give you more detailed specific advice depending on your individual results.
False Reactions: All laboratory tests can produce ‘false alarms’, the technical term for this is a ‘false reaction’. This is a positive result (usually a weak reaction) in the screening test, which, on confirmatory testing is shown to be negative. False reactions are a recognised complication of all biological tests and are perfectly normal. They are of no significance for the health of the donor.
If you have given blood and you become unwell (except for a cold) in the
2 weeks following your donation, ring our donor helpline on 0845
7 711 711 as soon as possible.
Tests On Your Blood PDF
Tests On Your Blood (Welsh) PDF
To download
Adobe Acrobat Reader please click here.
View Current Blood Stocks
Privacy & Legals notice
RETURN
TO TOP OF PAGE
|