The procedure for assessing RBC morphology includes examination of the smear in the feathered (thinner) edge where the erythrocytes are randomly distributed and, for the most part, lie singly, with only occasional overlapping. Image A is representative of an acceptable area for evaluation of RBC morphology. Notice that the majority of the cells can be clearly differentiated with only occasional overlap. If the area is too thin, the RBCs will appear flat and somewhat square (cobblestone effect) with no central pallor, as shown in Image B. If the area examined is too thick, the cells will be too close together to evaluate the morphology of individual cells, as shown in Image C.
Image A. An example of an acceptable area of evaluation with minimal overlapping.Image B. An example of a thin area, not acceptable for evaluation.Image C. An example of a thick area, not acceptable for evaluation.