Good laboratory stewardship: Transitioning from clinician-ordered peripheral smear reviews to laboratory-derived smear reviews (via a complete blood count with differential)

In conjunction with good laboratory stewardship, best practices and clinical evidence, Labcorp has discontinued the clinician-ordered Hematopathology Consultation, Peripheral Smear (test number 005300) in favor of a Complete Blood Count (CBC) with Differential (test number 005009).

Labcorp’s complete blood count with differential uses a sophisticated laboratory-derived smear review (LDSR) methodology with a complex set of rules and flags to determine if a smear review is required; if abnormalities are detected, a smear review will be performed.

Rooted in good laboratory stewardship and the incredible industry advancements in hematology analyzers, this change comes with an eye toward holistic patient care, potentially improved turnaround times and comprehensive reporting of severe abnormalities. We recently sat with our co-discipline directors in hematology to discuss the reason for this change and how Labcorp is supporting providers in patient care. 
 

Hear from our experts

Q: What insights do peripheral smear reviews provide clinicians?

A peripheral blood smear is a test that examines red and white blood cell morphology through microscopic examination. This test is performed by qualified laboratory personnel who look for changes in cell and platelet size and shape, as potential signs of a blood disorder or blood cancer. Clinicians often order a peripheral smear review to be interpreted by a pathologist based upon the clinical picture of the patient. This may be ordered upfront or in consequence to a prior CBC.

Q: What is a laboratory-derived smear review (LDSR) and how is it related to a CBC with differential?

Utilizing sophisticated hematology analyzers, our CBC with differential employs complex flags and rules to determine whether abnormalities exist and whether a smear review is required. This methodology is referred to as LDSR. The hematology analyzer determines that the sample has met the criteria requiring a smear review; a smear review is performed automatically when these flags and/or rules are triggered.

Q: Is Labcorp doing away with peripheral blood smears altogether?

No. As noted, this service will continue to be available through the CBC with differential test code. The sample will be analyzed using the hematology analyzer’s complex set of rules and flags. If abnormalities are detected, the smear is first screened by qualified laboratory testing personnel and escalated to a pathologist based upon set criteria (e.g., significant numbers of immature and/or atypical white blood cells, significant increases in specific WBC lineages (i.e., monocytes, basophils) suggestive of hematological malignancy, abnormal red blood cell morphology suggestive of hemolysis, intracellular organisms or blood parasites present, and/or significant abnormal platelet morphology).

Q: Will the patient report indicate if the CBC flagged the sample for review? And if a smear review was performed, will the pathologist’s comments be provided?

If a smear review is performed, it will be noted on the patient report. It will also be noted on the report whether it was reviewed by a qualified medical technologist or pathologist. If the review was performed by the medical technologist, the report will include a statement indicating that either a manual differential was performed or that the analyzer findings were confirmed by a smear review. If a review is performed by a pathologist, the report will indicate that a pathologist review was performed per protocol, and it will include interpretive comments on the white blood cells, red blood cells and platelets. If indicated, recommendations for follow-up testing may also be included.

Q: Is the LDSR methodology comparable to clinician-ordered smear review? Can it detect the same abnormalities?

Yes, and for several reasons. First, the technology: hematology analyzers have been around for more than 50 or 60 years and over the past several decades have become more sophisticated. They use a flow cytometry technology as well as other types of sophisticated rules and techniques that can catch abnormal cell populations.
From a laboratory stewardship perspective, literature speaks to how the clinician-ordered hematopathology smear review is of low clinical utility.^1,2 Before undertaking an effort of this magnitude, we conducted our own internal study, which is nearing publication. 
In that study, several hundred CBC samples were reviewed, comparing anomalies found via the clinician-ordered smear reviews to ones that would need to be detected via the LDSR methodology. There were no major discrepancies in hematologic abnormalities between the two methods. In fact, all major abnormalities, including myelodysplastic syndrome, abnormal neutrophils, schistocytes and spherocytes, were proactively flagged under our laboratory-derived methodology’s criteria and rules. All would automatically move into a human smear review.
This is great and reassuring data. We seek to blend this wealth of experience, data and shared scientific knowledge to help providers by supplying the right tests for the right patient at the right time.

Q: For providers that currently run a CBC on-site, can Labcorp use the same patient sample? Does the provider need to prepare a separate slide for the smear review?

If the customer sends the original lavender-top (EDTA) tube including sufficient volume that meets stability requirements as defined in our test menu (72 hours refrigerated; 24 hours room temperature), Labcorp can use this sample. The customer will not need to prepare and package slides for the smear review. In the event an abnormality is detected through the Labcorp CBC with differential, Labcorp will prepare the slide for smear review.

Q: From a patient and clinician viewpoint, what are the benefits of a CBC with differential that utilizes a LDSR reflex methodology?

There are many benefits to a LDSR methodology, including faster turnaround time, earlier reporting of all results and improved efficiencies. The hematopathology smear review’s published turnaround time is two to four days. The process involves a pathologist looking and reporting on each slide, many of which have no significant abnormalities, meaning unnecessary reports are generated. Frequently, the CBC is ordered separately from the hematopathology consultation smear review, and a clinician may need to wait for two reports for complete information.
This new process with a CBC with differential that will reflex with significant abnormalities means that reporting can happen within one business day of the draw. Providers will receive one patient report that includes both the CBC results and the pathologist’s review.
In addition, some reviews that are ordered will show nonspecific abnormalities. We have created a CBC with differential results guide to help clinicians better understand the differential diagnoses of these abnormalities.

Q:  Labcorp Oncology offers a peripheral blood morphology. Is this the same as test number 005300, the hematopathology consultation? Will that still be available?

The hematopathology consultation (test number 005300) is not the same as a full hematopathology and peripheral blood morphological evaluation and consultation available through Labcorp Oncology. The consultation offered through Labcorp Oncology is more comprehensive and includes a manual differential on the peripheral blood and descriptions of abnormal cell populations. This test is usually run along with flow cytometry and cytogenetics and all results correlated to provide a diagnosis or recommendations for additional testing. 
Labcorp Oncology clients can continue to order the morphological evaluation and hematologic consultation via Labcorp Oncology Services. For more information on Labcorp Oncology, please contact your Labcorp sales representative.  

Q. Is moving from clinician-ordered peripheral smear reviews to the automatic LDSR an industry change?

Yes. As hematology analyzers have become more sophisticated, there is a movement toward LDSRs. Education is key to understanding the utility and clinical benefit of this technology. As part of this initiative, Labcorp presented on this topic at a National Laboratory Stewardship Conference, and many organizations nationwide are in various stages of implementing this change. Labcorp is committed to good laboratory stewardship, sharing best practices and disseminating clinical information as we seek to be the laboratory services provider of choice for patient benefit.

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