Blood smear

Blood smear, sometimes called peripheral blood smear (probably to distinguish it from a bone marrow aspirate?) is a Giemsa stained thin film of blood on a glass microscopic slide. It allows morphological examination of blood cells and platelets. It's used in the evaluation of anaemia and leukaemia.

In many types of anaemia there is abnormal morphology of the red blood cells, like in sickle cell anaemia, hereditary spherocytosis, etc. One can also see pathological features like punctate basophilia (seen in some forms of heavy metal poisoning and some hereditary anaemias), and Howell-Jolly bodies (seen in hypoasplenism).

In leukaemia the leukocytes are monoclonal and therefore have a very similar morphology, while in case of infections the leukocytes are polyclonal and therefore have a more varying morphology.