Blood groups - What blood is used for

Donated blood is often used to replace blood lost during surgery or an accident.

In the UK, blood is not used whole but separated into red cells, platelets and plasma so it can be used in various treatments.

However, in cases where a severe amount of blood has been lost, all three blood components can be given in a blood transfusion.

Blood transfusions

A blood transfusion is where blood is taken from one person (a donor) and transferred into another person.

The blood is transferred directly through the blood vessels (intravenously). Some blood groups cannot be mixed with each other, so the blood group you receive must be compatible with your own.

For example, if you are blood group A, you cannot take red cells from a person with blood group B because the anti-B antibodies in your blood will fight the B antigens in the donor's blood. This causes the donated red cells to be destroyed, which can be fatal.

Blood group O- red cells have no ABO or RhD antigens and can be given to almost anyone. Someone with blood group AB+ can usually receive red cells from any group, but AB+ red cells can only be given to a person with blood group AB+.

Your blood group will be identified using a blood group test before a blood transfusion takes place.

How blood is used

Blood is separated into its various parts and each part is used to treat different conditions. There are many conditions treated by donated blood.

Red blood cells

Red blood cells are used to treat all types of anaemia, such as in cancer, for example, or bone marrow disease and sickle cell disease. They can also be used to replace red blood cells lost in accidents, surgery and childbirth.

Platelets

Platelets can be used in conditions that cause the platelet count to be very low, including bone marrow disease and leukaemia (cancer of the white blood cells). They can also be used with chemotherapy and in people who have had a blood stem cell transplant.

Plasma

Plasma can either be frozen or processed for use in a wide variety of treatments.

Frozen plasma is used to replace blood clotting factors when there is massive blood loss; for example, following a severe injury.

It may also be needed for conditions that decrease the production of clotting factors, such as liver disease. A protein called albumin found in plasma can also be used to treat burns.

Processed plasma is important for treating all types of haemophilia (a genetic condition that affects the blood's ability to clot).

It can also be used to treat pregnant women with RhD negative blood who are carrying a baby with RhD positive blood inherited from the father.

Processed plasma can also be used when producing antibodies that are used to treat conditions such as: