Comparison of fresh and overnight blood sample

 
old versus fresh blood

Smears made from the same blood sample immediately after collection (upper panel) and after overnight storage at refrigerated temperature (lower panel). Target cells and neutrophils with condensed chromatin are seen in the freshly made smear. In contrast, numerous echinocytes (burr or crenated cells) are seen in the smear from stored blood. The neutrophil nuclei have also swollen, with lighter (less condensed chromatin) than normal and there is polarization of neutrophil granules to one side of the cell. Such swelling of neutrophil nuclei can result in the formation of “false” bands, preventing an accurate differential leukocyte count (may be mis-interpreted as a true left shift or inflammatory leukogram).

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