The study of the formed elements of blood and the blood forming tissues. Quantitative information is derived by counting the numbers of red blood cells, white blood cells and platelets present in a sample of whole blood.
Qualitative information is obtained by microscopic examination of a stained blood film. The numbers and appearance of the red blood cells allow the medical scientist to identify various types of anaemia. Examination of the white blood cells enables, among other things, the differentiation of infection and leukaemia.
Platelets are small cellular fragments vital to the process of blood clot formation and a change in their numbers can indicate a bleeding disorder. Levels of various proteins that interact to clot blood can be determined. Such tests aid in the diagnosis and management of patients who have defects in their blood clotting system and are also valuable in the monitoring of patients receiving anticoagulant therapy.