Branches
Blood is studied by several specialties that overlap in the clinic. They differ in which component they watch and what goes wrong with it.
| Branch | What it studies | Typical question |
|---|---|---|
| Haematology | Blood, bone marrow and their diseases | Why is this patient anaemic? |
| Transfusion medicine | Collecting, testing, storing and giving blood components | Which unit is safe for this patient? |
| Immunohaematology | Blood group antigens and the antibodies against them | What is causing this transfusion reaction? |
| Haemostasis and thrombosis | Clotting and its disorders | Why does this family bleed — or clot — too easily? |
| Haemato-oncology | Leukaemia, lymphoma, myeloma | Which mutation is driving this leukaemia? |
| Stem cell and marrow transplantation | Replacing the blood-forming system | How good a match is this donor? |
| Haemoglobin disorders | Sickle cell disease, thalassaemias | Can the fetal form of haemoglobin be switched back on? |
| Laboratory haematology | Counting and examining blood cells | What does this blood count mean? |
Why matching matters
Give group A blood to a group B patient and antibodies already in the patient’s plasma attack the transfused cells within minutes. Group O red cells carry neither A nor B and can usually be given to anyone, which is why O negative is kept for emergencies; group AB plasma, for the mirror-image reason, suits any recipient. Beyond ABO and Rh, patients who are transfused often are matched for further groups.