Give Blood England and Wales

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 many 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.

We use two tests for HBV infection. One 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 have long - term infection and are often called "carriers" of the virus. It is usual to feel completely well, even when the HBV infection has been present for many years. Acute hepatitis B infection is uncommon in blood donors. Occasionally we get a positive result in this test because the donor has recently had an immunisation against hepatitis B and not because infection is present.

The second test is an HBV virus (NAT) test, which also detects virus material directly. It will pick up an acute infection a few days earlier than the antigen test, and may also be positive when there are very low levels of HBV infection present, and the antigen test is showing negative.

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.

We use two different tests for HIV infection.

One test is a combined antibody and antigen test ("combo test"). This will detect antibodies to HIV, which represent persistent infection with the virus, and also detect the HIV antigen, which is present on the HIV virus. Unlike for many other infections, the presence of antibodies to HIV shows that the virus is present, and not that the infection is in the past. HIV antigens are usually detectable very early in HIV infection, and late on when the person is becoming ill. The HIV antigen test is added to the antibody test to increase the chances of picking up a very recent HIV infection.

The second test we use is an HIV virus (NAT) test. This test detects the virus material directly and will pick up infection a few days earlier than the "combo test". It is used to detect very recent infection. It may give a negative result later on, so cannot be used instead of the HIV antibody test.

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 (HCV NAT test). The test for virus is an extra safety test and can tell us whether a donor with antibodies has current infection, or has recovered from the infection. 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.

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 0300 123 23 23 as soon as possible.

Tests On Your Blood (PDF, 197K)

Tests On Your Blood Welsh (PDF, 327K)