CLSI H20
Reference Leukocyte (WBC) Differential Count (Proportional) and Evaluation of Instrumental Methods
This standard provides comprehensive guidelines for evaluating the performance of automated and semiautomated hematology instruments in accurately performing leukocyte (WBC) differential counts. It establishes the reference manual-visual WBC differential, defines acceptable abnormalities, and ensures reliable and consistent blood film analysis.
This reaffirmed document has been reviewed and confirmed as suitable to remain published without revision to content, as of September 2016.
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{{FormatPrice(nonMemberPrice)}} List PriceClinical and Laboratory Standards Institute document H20-A2—Reference Leukocyte (WBC) Differential Count (Proportional) and Evaluation of Instrumental Methods; Approved Standard—Second Edition evaluates automated and semiautomated hematology instruments for their capability to perform an acceptable leukocyte (WBC) differential count. The standard focuses on WBC found in blood films. The standard presents a detailed description of an acceptable manual-visual WBC differential count, which serves as the reference for the instrumental differential counter. The types of abnormalities for inclusion are outlined. A statistical method is also outlined, allowing for the determination of the performance of the test method in qualitative, as well as quantitative abnormalities.
This document replaces the approved standard, H20-A, which was published in 1992. Several changes have been made in this edition; chief among them is the introduction of a new orthogonal regression method for comparing duplicate data, in Section 12. The document has also been updated to include the following: a new examiner qualification process in Section 6.6.5, revision of Section 9.2, Data Acquisition to clarify the instructions for randomization of the morphology examination slides, Table 4 has been updated with the new NHANES data, and the method of arbitration for resolving discrepant findings of the morphologists has been updated.
These recommendations cover performance testing of leukocyte (WBC) differential counting. Only those WBC found in normal (nondiseased) individuals will be addressed. These cell types are: neutrophils (segmented), neutrophils (band forms), lymphocytes (normal), lymphocytes (variant forms), monocytes, eosinophils, and basophils. If not identified, the system should appropriately flag other cells as abnormal, suspect or unclassified, or as nucleated red blood cells (NRBC).
Some devices may group several cell types into a single category. For example, segmented and band neutrophils, eosinophils, and basophils may be combined as granulocytes.
This document is available in electronic format only.
The U.S. Food and Drug Administration (FDA) has evaluated and recognized this approved-level consensus standard for use in satisfying a regulatory requirement.
Clinical and Laboratory Standards Institute document H20-A2—Reference Leukocyte (WBC) Differential Count (Proportional) and Evaluation of Instrumental Methods; Approved Standard—Second Edition evaluates automated and semiautomated hematology instruments for their capability to perform an acceptable leukocyte (WBC) differential count. The standard focuses on WBC found in blood films. The standard presents a detailed description of an acceptable manual-visual WBC differential count, which serves as the reference for the instrumental differential counter. The types of abnormalities for inclusion are outlined. A statistical method is also outlined, allowing for the determination of the performance of the test method in qualitative, as well as quantitative abnormalities.
This document replaces the approved standard, H20-A, which was published in 1992. Several changes have been made in this edition; chief among them is the introduction of a new orthogonal regression method for comparing duplicate data, in Section 12. The document has also been updated to include the following: a new examiner qualification process in Section 6.6.5, revision of Section 9.2, Data Acquisition to clarify the instructions for randomization of the morphology examination slides, Table 4 has been updated with the new NHANES data, and the method of arbitration for resolving discrepant findings of the morphologists has been updated.
These recommendations cover performance testing of leukocyte (WBC) differential counting. Only those WBC found in normal (nondiseased) individuals will be addressed. These cell types are: neutrophils (segmented), neutrophils (band forms), lymphocytes (normal), lymphocytes (variant forms), monocytes, eosinophils, and basophils. If not identified, the system should appropriately flag other cells as abnormal, suspect or unclassified, or as nucleated red blood cells (NRBC).
Some devices may group several cell types into a single category. For example, segmented and band neutrophils, eosinophils, and basophils may be combined as granulocytes.
This document is available in electronic format only.
The U.S. Food and Drug Administration (FDA) has evaluated and recognized this approved-level consensus standard for use in satisfying a regulatory requirement.