The role of blood film examination in diagnostic heamatology has continued to be very relevant in the practice despite the advancement in equipment such as haematological analyzers with capacity to do differential count and Flow Cytometry in cell, cell recoginition, classification and identification. The blood film is still very useful in the evaluation of the anaemias and performance of differential leucocyte count. It is equally useful in the evaluation of platelet disorder in terms of size, shape and number in thrombocytosis and thrombocytopenia. It is also very useful in the recognition of the developing stages of the white and red cell which contributes to the diagnosis of leukaemias, leukaemoid reactions and erythrocytosis. The blood film may be stained with cytochemical stains, supravital stain for further contribution to the diagnosis of leukaemia, anaemias and other proliferative disorders. The blood film may be used as a diagnostic feature in the infections of the blood system.
The draw backs in the blood film as a diagnostic tool include the fact that:
It is labour- intensive and technical skill demanding the making, staining and examination of the blood film. Inability to spread the blood cell uniformly and the ability for cell to selectively locate themselves in certain location of the slide; such formation of smear cells in certain disease conditions, the larger cell settling at the edges of the slide, stack of red cells at the thicker portion of the slide and red cell without central pallor at the tail end of the slide. The need for elaborate training of the personnel examining the blood film even when the film is machine made is an important factor in the accurate performance of the exercise. However, the blood film examination can provide useful diagnostic information in short period of time at relatively low cost.