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September 6, 1976

Quality Control in Haematology

Author Affiliations

Cook County Hospital Chicago

JAMA. 1976;236(10):1173. doi:10.1001/jama.1976.03270110069041

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Although "quality control" is a familiar concept in manufacturing, it is not a uniform practice in all medical laboratories. Many physicians do not realize that a test can be precise (repetitively getting the same number) without being accurate (correct in relation to an accepted standard). The sensitivity and range of given tests may also be tremendously influenced by the presence of other drugs or pharmacologically active metabolites.

Intralaboratory control (internal) can check on the reproducibility but not guarantee accuracy. External quality control allows a laboratory to compare its precision and accuracy against other laboratories. This task is difficult enough when all agree on how to do the test and what reagents should be used. Then, too, more problems obviously exist in differential counting of white blood cells than in determination of the hemoglobin values, hematocrit values, and the red blood cell count. The introduction of mechanized equipment has improved the