Early scientists were amazed when they looked at blood under the microscope and found that it contained cells as well as fluid. There are red cells for carrying oxygen, several types of white cells for fighting infection, and platelets for helping blood to clot. Haematologists are experts in blood cells, including those already in the blood and those being made in the cell factories of the bone marrow. Many diseases involve blood cells. They include anaemias (where there are not enough red cells), leukaemias (where there are too many white cells), haemophilia (where the blood does not clot properly) and bone marrow diseases (where the cell factories go wrong).
Haematologists also supervise blood transfusion, which provides replacement blood for patients who have lost or cannot make their own. Haematologists have both clinical and laboratory responsibilities, so in this specialty the doctor who looks after you in the clinic or on the ward will be the same person who has examined your blood or bone marrow under the microscope.
Haematologists investigate, diagnose and treat diseases such as anaemia, leukaemia and lymphoma.
Transfusion medicine is the therapeutic application of transfusion science and the appropriate use of transfusion therapy to treat patients with a variety of conditions including cancer and leukaemia.