The criteria for a satisfactory blood smear include:

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When a satisfactory blood smear is observed macroscopically,the body of the film should be smooth and not interrupted by ridges,waves,or holes.It should be thickest at the origin and gradually thin out,rather than having alternating thick and thin areas.A good blood film should cover half to three-fourths of the length of the slide.All of the initial drop of blood should be incorporated into the film,not just part of it.The thin end of the smear should have a good feather edge; that is,the film should fade away without a defined border on the end.In some institutions a fairly straight feather edge is sought,while others prefer a more tongue-like edge.A defined border at the end of a blood film indicates that most of the WBCs have piled up at the end.When this occurs,the heavier neutrophils accumulate at the end to a greater extent than the other types of WBCs,giving an incorrect distribution of the types of WBCs in the body of the smear.Platelets also tend to accumulate at the end of a smear,decreasing the number in the body of the smear.This will also result in inaccurate percentages for the cell types within the body of the film,as the relatively stickier neutrophils and platelets tend to concentrate in such tails.

The Criteria for a Satisfactory Blood Smear Include