There are four main blood groups - O, A, B and AB. Group A is the most common group but Group O is most in demand.

To learn more about blood groups

Technological and medical advances enable the Blood Service to optimise the use of each donation which is usually divided into three components;

1. Red Cells

Red cells carry oxygen and are used to treat blood loss resulting from trauma and surgical operations.
Some cardiac operations can use up to 20 donations. Liver transplants would normally use 10 - 15 donations and a hip replacement 2-6 donations.

2. Platelets

These play an important part in the clotting process.
Platelets are widely used in the treatment of cancers like Leukaemia. One patient can require the platelets from 10 or more individual donations every day for a number of weeks.

3. Plasma

Plasma is a yellowish fluid in which the blood cells described above are suspended. It contains clotting factors such as factor VIII which is used in the treatment of haemophilia, albumin used for the treatment of surgical shock or severe burns, and immunoglobulins which protect the body against infectious diseases and are used in the treatment of immunodeficency.

- so each donation can help treat several patients!

In addition to the above, there are many other blood products that are made from whole blood to treat a wide variety of illnesses.