Valerie Neff Newitt
February 2025—In the 2024 accreditation program checklist edition, released Dec. 26, are new and revised requirements for chemistry, diagnostic immunology, and flow cytometry laboratories. Two of the flow cytometry requirements are now also in the anatomic pathology checklist.
CHM.31150 Prenatal Screen Risk Calculation requires the laboratory to determine which information and adjustments to include in the prenatal screening risk calculation and to document the rationale for excluding any of the expected elements. They include gestational age, in vitro fertilization method if applicable, initial or repeat testing, maternal age and weight, maternal race or subpopulation as defined by the lab, medications to control diabetes, multiple gestation if applicable, and smoking status.
If additional elements are included in the risk categorization calculation, the rationale for doing so must also be documented.
Multiple checklist requirements have been rolled into this one new requirement for greater simplicity, says Ann Moyer, MD, PhD, consultant at Mayo Clinic, Rochester, in the Department of Laboratory Medicine and Pathology and former chair of and advisor to the CAP/ACMG Biochemical and Molecular Genetics Committee. “Laboratories can think about each one of those elements and decide if they need to include it in their adjustments or not.”
Before the multiple requirements were combined into one, each of the elements was its own requirement, which had a detailed note, and that level of detail is no longer provided. “Laboratories are better served to look for more recent literature while they’re thinking through what they are including,” Dr. Moyer says. At this point, she adds, there are few large studies and professional society guidelines and recommendations. “But if labs are looking at their own data, they may be able to determine which of these elements is important or not in their patient population.”
For nuchal translucency screening, CHM.31950 Nuchal Translucency Measurement Quality says if screening panels are offered using nuchal translucency values, the laboratory must have a process to ensure the quality of those measurements. “The change in this requirement is that laboratories will need to identify a way to ensure that the sonographers provide accurate results,” because the program that used to exist for that purpose—Nuchal Translucency Quality Review—has been discontinued, Dr. Moyer says.
Microbiology and transfusion medicine
checklist requirements
Continuing to ensure performance is as expected is important, in the CAP’s view, “but the checklist leaves it to laboratories to develop a process they are comfortable with to ensure the quality of the measurement,” she says.
Other requirements in the chemistry checklist are new or have been revised.
A new requirement in the chemistry checklist is CHM.15225 eGFR and LDL Cholesterol Calculated Test Results. It requires that clinicians have access to information about the equation used to calculate results for estimated glomerular filtration rates and LDL cholesterol. The information can be made available in various ways, among them the patient report or test reference guide, for example, or by including the equation name in the name of the test. This requirement is identical to those in other checklists: LSV.41325 and POC.04425.
Also in the chemistry checklist, CHM.33900 Collateral Circulation has been revised. For radial artery sampling, CHM.33900 requires that a test for collateral circulation be performed before arterial puncture if clinically indicated and for results to be recorded.
Stephen Sarewitz, MD, advisor to and immediate past chair of the CAP Checklists Committee, says the requirement was revised to clarify that the laboratory and its client clinicians can determine whether to perform a test for collateral circulation prior to radial artery puncture and then to document the circumstances, if any, when such a test is needed.
The reason for the clarification, he explains, is that the Checklists Committee heard from some pathologists, anesthesiologists, and pulmonary physicians that such tests are unnecessary prior to radial artery puncture. “However, other pathologists and anesthesiologists were uncomfortable with removal of the requirement. It was therefore reworded in a way that clarifies it is up to each laboratory and its clinicians to determine when and if the test is necessary.” LSV.41370 and POC.08760 are the same requirements.
In diagnostic immunology, IMM.41420 Syphilis Antibody Screening says if the laboratory offers syphilis screening, a complete screening algorithm is followed, including appropriate confirmatory/secondary tests. Screening can be performed by initial testing with a nontreponemal antibody test (traditional syphilis screening) or a treponemal antibody test (reverse sequence syphilis screening). The reverse screening algorithm (with antitreponemal antibody testing performed initially) may be preferred in cases of recent infection or in cases of late latent or tertiary syphilis when nontreponemal antibodies may not be detectable.
“Previously, the checklist requirement didn’t address the traditional screening method, which is to screen with a nontreponemal antibody test first and, if positive, follow up with a treponemal antibody test,” says William J. Karlon, MD, PhD, vice chair of the CAP Diagnostic Immunology and Flow Cytometry Committee and director of the UCSF Clinical Laboratories at China Basin. “So we’ve updated this requirement to include both screening methods, following CDC recommendations for testing.”
In the flow cytometry checklist, too, are new and revised requirements.
FLO.23325 New Reagent Lot/Shipment Confirmation of Acceptability requires labs to evaluate the performance of new lots/shipments of antibodies and reagents before or concurrently with their being placed into service.
“We revised the language to make it very clear that labs should parallel test or have some other acceptability criteria for every new lot or shipment of the majority of reagents used in the laboratory,” Dr. Karlon says. FLO.23325 in the past two years has been one of the requirements cited most often as a deficiency.
Many different flow reagents cover many different areas, he notes. “So there’s a lot of variety, and sometimes it can be a bit confusing as to which things labs do need to parallel test.”
The requirement says inert reagents are exempt from the requirement. This was added, Dr. Karlon says, “because when it wasn’t in the requirement, it was unclear to labs whether they had to parallel test things like sheath fluids, cleaning fluids, or saline, and now we’ve said specifically that labs do not have to parallel test those with the old lot.”
FLO.23335 New Antibody Cocktail Confirmation of Acceptability is a new, related requirement, which says the lab must evaluate the performance of newly prepared antibody cocktails before or concurrently with their being placed into service and assign an expiration date for the cocktail. “FLO.23325 focuses on the original reagents, and FLO.23335 focuses on the cocktail,” Dr. Karlon says.
In the prior edition of the checklist, FLO.23325 said laboratories had to parallel test the old and new cocktail together. FLO.23335 was added, Dr. Karlon explains, to say, “Since you parallel tested the individual components, now you have different ways of confirming the acceptability of the cocktail as a whole.” Previously, the lab had to parallel test it directly, “but now we’re saying you can put it into use and then have criteria for acceptability once you see the results.” In recognition of periodic supply chain problems, both requirements note alternatives to parallel testing to define acceptability.
FLO.23737 QC—Flow Cytometry Reagents/Stains—Qualitative Assays says the lab must evaluate negative and positive staining patterns of residual normal cell population for qualitative assays (leukemia/lymphoma analysis, for example) each day of patient testing. This requirement, too, is an oft-cited deficiency and one that tends to generate many questions, Dr. Karlon says, and thus it has been revised to simplify it.
As the requirement existed previously, laboratories had to do a daily and a monthly QC. “The idea was to do a relatively brief check daily, but on a monthly basis laboratories needed to focus in and make sure every individual thing was performing properly. It was confusing to have different processes performed daily versus monthly.”
Now, laboratories will have to ensure their daily procedure confirms that each antibody or stain used performs acceptably. “That will be the biggest impact to laboratories,” Dr. Karlon says.
The evaluation can be run concurrently with active patient samples as long as the evaluation takes place before patient results are released. “We added that language to the requirement,” he says, “to give labs a bit more flexibility in how they implement this.”
If a component/tube of an assay or panel is not run on a particular day, the evaluation does not need to be performed on that component. “Flow cytometry is a little unusual in that typically standard panels are run depending on the clinical history or sample type, but there may be days when parts of the assay are not run,” Dr. Karlon says, adding that labs would often ask if they had to do QC daily on that component. “Now the requirement says if you’re not running it that day, no, you don’t need to perform the QC for it.”
Ideally, laboratories will have a positive and negative control for each antibody/stain included in the assay. Most labs will use residual normal cells present in patient samples as a control, he notes, but commercial materials such as cell lines can be used also. The requirement provides examples of acceptability criteria: CD2: normal T cells positive, normal B cells negative; CD19: normal T cells negative, normal B cells positive; and CD45 tube 1: positive in mature lymphocytes, negative in erythroid precursors. Some antigens are encountered only rarely, such as CD30, and an exception is provided to test these less frequently.
FLO.30275 Carryover Mitigation says the laboratory must have a process to evaluate and mitigate against carryover when applicable, including rare event assays (MRD, PNH) and paucicellular specimens such as CSF. Previously, this requirement was in the section on rare event flow cytometric assays and was applicable only to measurable residual disease testing and paroxysmal nocturnal hemoglobinuria testing. “The committee thought those two aren’t the only situations where carryover might have an impact on your assays,” Dr. Karlon explains, and thus the requirement is now in a more general section of the checklist and more broadly applicable, with paucicellular specimens provided as an example.
FLO.30595 Diluted Samples is a new requirement that says samples with high cellular concentrations must be diluted to yield a result within the analytical measurement range of the assay. This is typically used for stem cell collection for transplantation, Dr. Karlon notes. “There’s a real need for accuracy in this kind of assay because it has a direct impact on the timing of the collection of the stem cells and the transplantation. It’s critical that labs get this right.” In flow cytometry, there are few assays that require dilution, “so this requirement has been added to bring flow cytometry in line with all the other dilution processes” in the laboratory.
“The lab needs to confirm that its dilution process works appropriately so they’re getting the correct numbers,” he says, adding, “We think labs were in compliance with this, but now we wanted to have it documented.”
FLO.30610 Cellular Viability requires labs to define when the percentage of viable cells in each test specimen is measured, and FLO.30820 Rare Event Flow Cytometric Assays requires the lower limit of enumeration to be included in the diagnostic report. “These are existing requirements in the flow cytometry checklist,” where they will remain, “and we’re adding both of them to the anatomic pathology checklist to provide additional guidance to anatomic pathology labs that perform interpretation of flow cytometry data with an outside lab performing the technical component,” Dr. Karlon says.
One is ANP.29680 Cellular Viability and says the lab must ensure that the percentage of viable cells in each test specimen is provided by the lab that performs the flow technical component, when applicable. The other, ANP.29720 Rare Event Flow Cytometric Assays, is identical to FLO.30820.
“We believe labs doing this work are compliant already, though they may have to get additional information from the lab performing the technical component, but that should be the only impact,” Dr. Karlon says. “It’s simply a matter of ensuring all the appropriate requirements are in the right checklists. This is another step in the right direction.”
Valerie Neff Newitt is a writer in Audubon, Pa.