1/12. Red blood cell (RBC) antibody tweetorial. There are over 700 known RBC antigens. Every time someone is exposed to a red cell antigen that they don’t express, usually through transfusion, they may produce a corresponding antibody.

2/12. This can cause haemolytic transfusion reactions immediately, or with future blood transfusions. Therefore every time you send a ‘group and save’ the transfusion lab will 'group' the patient red cells (usually for ABO, Rh and Kell antigens) and check an antibody screen.

3/12. The clinical significance of any antibody detected will depend on the antibody type, concentration and known clinical behaviour of that antibody.

4/12. The exceptions in terms of antibodies are Anti-A and Anti-B which we all have if we do not have the corresponding antigen. For example I am A+, and although I have never been transfused I will have anti-B (thought to be from protein exposure as neonate).

5/12. Antibodies are a particular issue in pts. who are chronically transfused e.g. pts with haemoglobinopathies (esp. sickle cell anaemia) and haem cancers, because the more blood is transfused, the more antibodies may develop, and more difficult it is to find appropriate blood

6/12. To minimise the chance of this, patients who are expected to have many transfusions will have ‘extended phenotyping’ performed. This identifies more of the clinically significant antigens (than standard ABO/Rh/K) to allow better matched transfusions.

7/12. It also allows better identification of antibodies in the future, as if the patient is known to be FyA positive for example, we know that they cannot generate an anti-FyA antibody and this makes it easier to 'find' significant alloantibodies when testing in the lab.

8/12. Extended phenotyping cannot be used if a pt. has had transfusion in the last 3 months (life of an RBC), as it may identify donor RBC groups instead/as well as recipient. In that case, genotyping can be performed (for most of the same antigens).This is more expensive however

9/12. If a patient does have a red cell antibody and is planned for surgery – plan in advance. Let the transfusion lab know and provide a fresh G&S a few days in advance so they can stock the blood.

10/12. Think about blood saving strategies e.g. minimally invasive surgery, tranexamic acid, cell salvage. Remember – no patient with an antibody should ever die due to blood being withheld – in an emergency the lab will provide the best matched blood possible.

11/12. It is better to deal with a haemolytic transfusion reaction than a patient to suffer morbidity or die from delayed transfusion. The SHOT annual transfusion report consistently reports cases of patients who have died waiting for the ‘right’ blood.

12/12. If in doubt, ask the transfusion lab biomedical scientists about the blood available- they have a wealth of knowledge about it. Haematology on-call can also always offer advice. #blooducation