Editors: Olga Pozdnyakova, MD, PhD, Geoffrey Wool, MD, PhD, David Bernard, MD, PhD & Raul S. Gonzalez, MD
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Q. Our institution performs rapid onsite evaluation (ROSE). In cases in which multiple passes are done, we frequently encounter unsatisfactory specimens (debris, neutrophils, bronchial cells, etc.). These cases are rescreened by a cytotechnologist and pathologist. If the case goes to a different pathologist, those unsatisfactory slides are unnecessarily screened three times. They’re also included in the daily slide workload of the cytotechnologist. Can the onsite pathologist dispose of unsatisfactory Diff-Quik slides and keep just the counter formalin-fixed slides? Since ROSE is provided for that episode, can you comment on billing?
A. June 2025—All cytology slides must be retained for five years per 42 CFR §493.1105 of the Clinical Laboratory Improvement Amendments of 1988 and CAP checklist requirement CYP.06900 Slide Retention—Cytopathology. This includes any slides made during a ROSE procedure. While these slides initially may appear to be unsatisfactory or nondiagnostic, there may be times when it is necessary to rescreen them. Slides made from the same material—i.e. “counter slides”—may at times contain diagnostic material not present on the paired slide.
As to the billing aspect of ROSE, even if slide material is nondiagnostic, the pathologist has provided an interpretation, and the case can be billed accordingly based on the number of episodes.
College of American Pathologists. CYP.06900 Slide retention—cytopathology. In: Cytopathology checklist. Dec. 26, 2024.
Standard: Retention Requirements. 42 CFR §493.1105.
Michael R. Henry, MD
Director of Cytopathology
Department of Laboratory Medicine and Pathology
Mayo Clinic, Rochester, Minn.
Former Vice Chair, CAP Cytopathology Committee
The following question and answer was first published in April 2021. Periodically we republish answers to questions that remain important and current. At the time of initial publication, Dr. Pozdnyakova was a member of the CAP Hematology/Clinical Microscopy Committee and was with Harvard Medical School and Brigham and Women’s Hospital.
Q. Many times a platelet count on an automated hematology system indicates some degree of thrombocytopenia or the analyzer reports a high mean platelet volume or platelet large cell ratio, while a blood smear shows large platelets and/or giant platelets. Is it OK to include a comment in the report that the platelets are adequate or that the count could be due to large platelets, especially with values that indicate marked thrombocytopenia?
A. Modern automated hematology analyzers usually provide accurate platelet counts, especially hematology analyzers that, in addition to using electrical impedance, use alternative methods for counting platelets, such as optical technology (light scatter or fluorescent flow cytometry) or immunologic methods. Furthermore, computer algorithms for modern hematology analyzers recognize interference or an abnormal platelet distribution.
Automated hematology analyzers will flag an automated platelet count for quantitative changes, such as when the platelet count is below or above a laboratory-defined cutoff on a new patient or delta checks show significant variation in platelet count. They will also flag an automated platelet count for qualitative changes, such as platelet clumps, abnormal platelet distribution, giant or large platelets, red blood cell fragments, or an abnormal platelet scattergram.
When a platelet count is flagged, it is important to verify the count by estimating platelets from a well-prepared peripheral blood smear. This is necessary since inaccuracy can be due to platelet characteristics that overlap those of other cellular material, such as schistocytes and leukocyte cytoplasmic fragments, the presence of cryoglobulins, and the inherent ability of platelets to activate and clump. In addition, giant platelets may not be counted by automated analyzers because their size exceeds the normal threshold value. A platelet estimate from a blood smear is an acceptable method for counting platelets. Each laboratory should develop an adequate system for correlating automated platelet counts with manual microscopic counts to prevent reporting spurious thrombocytopenia (due to platelet clumps, giant platelets, or platelet satellitism) or thrombocytosis (due to microcytic red blood cells, cytoplasmic fragments, fungal or bacterial organisms, debris, or electronic noise).
To verify the platelet count, the entire blood smear, including the feather edge, lateral edges, readable area, and thick area, should be examined under low magnification for the presence of clumps of platelets. The blood smear should then be examined under higher magnification for the presence of red cell fragments, bacterial or fungal organisms, debris, and giant platelets. If any of these interferences are present, the automated platelet count is unreliable, and a platelet scan comment should be reported in qualitative terms as normal, increased, or decreased. The comment should also mention the type of interference—for example, “normal platelet count with giant platelets present” or “normal platelet count with red cell fragments present.”
If platelets are clumped after collection in an EDTA-anticoagulated tube that was well mixed at the time of collection, this may represent in vitro EDTA-induced changes. Platelets must be quantified from blood collected directly into a counting diluent using the anticoagulant recommended by the manufacturer of the counting diluent or by estimating the count from a non-anticoagulated blood film.
D’Souza C, Briggs C, Machin SJ. Platelets: the few, the young, and the active. Clin Lab Med. 2015;35(1):123–131.
Gulati G, Song J, Florea AD, Gong J. Purpose and criteria for blood smear scan, blood smear examination, and blood smear review. Ann Lab Med. 2013;33(1):1–7.
Segal HC, Briggs C, Kunka S, et al. Accuracy of platelet counting haematology analysers in severe thrombocytopenia and potential impact on platelet transfusion. Br J Haematol. 2005;128(4):520–525.
Tantanate C, Khowawisetsut L, Pattanapanyasat K. Performance evaluation of automated impedance and optical fluorescence platelet counts compared with international reference method in patients with thalassemia. Arch Pathol Lab Med. 2017;141(6):830–836.
Olga Pozdnyakova, MD, PhD
Director, Division of Hematopathology
Professor, Pathology and Laboratory Medicine
Hospital of the University of Pennsylvania
Philadelphia, Pa.
Chair, CAP Hematology/Clinical Microscopy Committee