Editor: Frederick L. Kiechle, MD, PhD
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Q. I have been tasked with doing a quality assurance review comparing automated differential results to the manual differential done on the same patient. Do you have recommendations regarding acceptable analytical criteria?
A. August 2024—A comparison study between a manual differential and a differential performed by a hematology analyzer is essential for verifying the performance of the automated differential. The comparison should be conducted using the laboratory’s data. Laboratory standardization guidelines, such as from the Clinical and Laboratory Standards Institute and International Council for Standardization in Haematology, and the hematology analyzer vendor can provide more comprehensive information on how to conduct the comparison study. The medical director should participate in conducting the study.
Most of these studies are performed during the laboratory’s validation/verification study of the hematology analyzer. However, if the comparison study was not previously done or was performed too long ago, a new comparison study may be warranted to include the variations within the laboratory’s manual differential and equipment.
A complete blood count with automated differential is reflexed to a manual differential due to numeric or morphology flags generated by a hematology analyzer deeming the automated differential inaccurate. In such cases, results from a 100- to 200-cell manual white blood cell differential are reported and override the automated results. Hence, correlation between an automated and manual WBC count is not needed in clinical practice.
The purpose of the quality assurance review cited in the question is unclear. The automated differential and manual differential comparison from a single patient potentially could be compared to more in-depth data generated from a full method comparison. Alternatively, the question might be whether the differential results from the two methods were discrepant. The discrepancy would prompt an intervention or cross a clinical threshold within a reference range or outside a reference range.
Briggs C, Culp N, Davis B, d’Onofrio G, Zini G, Machin SJ; International Council for Standardization of Haematology. ICSH guidelines for the evaluation of blood cell analysers including those used for differential leucocyte and reticulocyte counting. Int J Lab Hematol. 2014;36(6):613–627.
Clinical and Laboratory Standards Institute. H20-A2: Reference Leukocyte (WBC) Differential Count (Proportional) and Evaluation of Instrumental Methods; Approved Standard, 2nd ed.; 2007.
MacQueen BC, Christensen RD, Yoder BA, et al. Comparing automated vs manual leukocyte differential counts for quantifying the ‘left shift’ in the blood of neonates. J Perinatol. 2016;36(10):843–848.
Danielle L. V. Maracaja, MD, MHS
Clinical Associate Professor of Pathology and Laboratory Medicine
University of North Carolina at Chapel Hill
Chapel Hill, NC
Member, CAP Hematology/Clinical Microscopy Committee
Q. Can activated clotting time results handwritten by a perfusionist be sent to the laboratory to be entered into the laboratory information system?
A. Laboratory personnel who perform data entry may enter handwritten test results into the laboratory information system for testing performed and verified by qualified testing personnel. The laboratory must have a system that maintains the identity of the individual who performed the test and a process to detect and correct clerical errors in a timely manner. In addition, the laboratory must comply with applicable state laws and regulations pertaining to record retention, personnel qualifications, and type of supervision needed.
Standard: Test records. 42 CFR §493.1283(a)–(b) (2003).
Standard: Test report. 42 CFR §493.1291(a)(3) (2003).
Shelley Martire, MLS(ASCP)CM
Senior Technical Specialist
CAP Laboratory Accreditation Program
College of American Pathologists
Northfield, Ill.