Blood film

Blood film - A test that involves smearing a drop of blood on to a glass slide for examination under a microscope. The blood film is stained with dyes to make the blood cells show up clearly.

The test allows the shape and appearance of blood cells to be checked for any abnormality, such as the sickleshaped red blood cells characteristic of sickle cell anaemia. The relative proportions of the different types of white blood cells can also be counted.

This examination, called a differential white cell count, may be helpful in diagnosing infection or leukaemia. Blood films are also used in diagnosing infections, such as malaria, in which the parasites can be seen inside the red blood cells. Blood films are usually carried out together with a full blood count.