Development of a peripheral blood morphology proficiency assessment program using the CellaVision^® Proficiency Software

Hospital care for Nova Scotia’s growing population of ∼1,000,000 is distributed across 43 different sites, which range from large tertiary care and trauma centres to small community hospitals. Many diagnostic and complex care services are centralized at the QEII Health Sciences Centre (QEII-HSC) in the province’s capital city of Halifax. This teaching and research hospital complex is the main tertiary care referral centre for Nova Scotia, providing numerous advanced medical and diagnostic services for the Maritime Provinces. In recent years, significant advances have been made in standardizing the more routine diagnostic services offered in hospital labs throughout Nova Scotia. Provincial requests for proposals have secured equivalent diagnostic equipment throughout the province, while provincial standard operating procedures (SOPs) ensure every hospital performs laboratory tests identically.

Approximately 125,000 manual differentials are performed by medical laboratory technologists (MLTs) each year in Nova Scotia. Although the diagnosis of many hematologic disorders is now based on flow cytometry, molecular genetics, or karyotype analyses, the peripheral blood smear remains a crucial early test in the diagnostic work-up of a plethora of clinical presentations [1]. Because inter-rater agreement for peripheral blood morphology assessment can vary significantly [2], proficiency testing was adopted to monitor diagnostic performance throughout the province. In 2016, the QEII-HSC Division of Hematopathology launched the first iteration of the province’s peripheral blood morphology proficiency program. Glass slides prepared with patient blood samples were shipped to every hospital laboratory with a peripheral blood microscopy service. Every microscopy MLT evaluated the proficiency slide, performed a manual differential and identified any critical morphologic findings. These results were submitted to the QEII-HSC for adjudication by the proficiency program coordinators (i.e., the microscopy technical specialist, supervisor, and medical director). Early on, multiple shipments of subsequent proficiency cases were anticipated to be distributed throughout the province over time, as Alcaraz-Quiles et al. described [3]. Unfortunately, broken slides were returned to the QEII-HSC; these may have been damaged in transit between labs or during proficiency testing. Associated shipping costs were not insignificant, and it was impossible to ensure all morphologic findings were equally represented on each slide. Moreover, manually analyzing the performance of the 14 participating labs in a basic spreadsheet application proved onerous. A glass slide-based proficiency program’s workload and logistical challenges quickly became untenable, and distributed remediation and follow-up education were complex to organize from the centralized Halifax site using glass slides.

The next iteration of our proficiency program incorporated the CellaVision^® Proficiency Software, the sole peripheral blood proficiency software solution on the market. Our program was henceforth known as the Lorna Pearce Proficiency Program, or LP3, in honour of a former MLT who was a generous benefactor to the QEII-HSC Division of Hematopathology. The LP3 coordinators selected normal patient blood samples or those with morphologic abnormalities that should be detected and reported per the provincial peripheral blood morphology SOP. Slides were scanned using the CellaVision Peripheral Blood application on a CellaVision DM96 (2017–2022) or DM9600 (2022 onward) digital cell morphology system. The deidentified slide images were then uploaded to the CellaVision Proficiency Software, and the technical specialist and medical director established the correct grading of red cell findings and categorization of white cells. In 2017, all 14 hospital sites with microscopy services in Nova Scotia again enrolled in the LP3, with 213 fully trained microscopy MLTs participating in this mandatory program (Figure 1). We tracked the percentage of MLTs who completed the proficiency slide each month (Figure 2). There was excellent program uptake, with no less than an 86 % yearly completion rate. Education on the program’s intent to provide an opportunity to improve rather than identify and punish mistakes helped increase the completion rate in 2019 (Figure 2).

Figure 1:

Participation in the peripheral blood morphology proficiency program decreased over time. The number of individual hospital sites (white bars) and total medical laboratory technologists (MLTs; black line) participating in the peripheral blood morphology proficiency program from 2017 to 2022 are shown.

Figure 2:

Completion rates for peripheral blood morphology proficiency assessments. The percentages of total peripheral blood morphology proficiency assessments completed between 2017 and 2022 are shown.

The provincial SOP for peripheral blood morphology assessment and reporting incorporated recommendations from the International Council for Standardization in Haematology [4], 5]. A “passing” performance for a red blood cell finding in the LP3 was achieved when an abnormality was quantified to within one grade of the correct measure or, in the case of inclusions (e.g., Howell-Jolly bodies, Pappenheimer bodies, malaria babesia, etc.), if they were identified at all. MLTs were required to correctly categorize at least 90 % of the white cells. Pass rates were lowest for both red cells (59 %) and white cells (73 %) in 2017 and have since improved to ∼90 % or more (Figure 3). Various red and white cell findings were selected for the LP3 from the provincial peripheral blood morphology SOP, which defines critical findings and outlines how specific abnormalities should be categorized (Table 1). Whether an MLT passed or failed was based on how they categorized red and white cell findings according to the provincial SOP. The QEII-HSC recommended repeat testing of any MLT who did not pass a proficiency slide and formal retraining if an MLT failed three consecutive slides. While this approach was followed in the QEII-HSC, laboratory management at each hospital site made final decisions on the extent of remediation for their own MLTs. Additional slides were made available by the QEII-HSC upon request for retesting if required to remediate MLTs who did not recognize specific cells or morphologic findings. Failure to follow the SOP typically resulted in additional reading and testing relating to that document. The technical specialist at the QEII-HSC hosted virtual monthly meetings using the CellaVision Proficiency Software to review each proficiency slide with the participating provincial labs. The medical director also answered questions and provided additional education when needed. These sessions were recorded and made available to all microscopy MLTs in the province to review at their convenience.

Figure 3:

Pass rates for peripheral blood morphology proficiency assessments. The pass rates for all proficiency assessment participants between 2017 and 2022 are shown. Pass rates for assessments of red cell abnormalities (black bars) and white blood cell abnormalities (white bars) are represented individually.

The CellaVision Proficiency Software is a powerful tool for assessing peripheral blood morphology skills. Because it is cloud-based, it can be accessed by anyone with a software license and a suitable internet connection. By presenting individual cells to the user, the software allows morphology skills to be assessed, rather than general microscopy skills; this could not be done using glass slides. The software also greatly enhanced the quality of teaching and discussion during review sessions, and test slides stored in the software can be revisited at any time for additional training and practice. The CellaVision Proficiency Software was a convenient platform to expose MLTs to a variety of different peripheral blood findings. Only three of the hospitals in Nova Scotia have cancer treatment centers, while only two serve a significant pediatric population. Some technologists struggled to identify blasts and recognize normal morphology in newborns simply because they saw so few cases in routine practice. The QEII-HSC regularly reviews challenging cases from other hospital sites. The technical specialist and medical director revisited those cases in the proficiency program to provide additional exposure and education as needed.

We also used the CellaVision Proficiency Software to expose our technologists to peripheral blood findings that were uncommon in Nova Scotia. In recent years, we have seen a marked increase in tick-borne illnesses, including anaplasmosis and ehrlichiosis, as well as the first case of locally acquired babesia infection [6]. Perhaps owing to extensive local media coverage of the increase in tick-borne illness, our technologists were excellent at detecting granulocytic anaplasmosis (Table 1). An increase in malaria cases has accompanied a surge in immigration to Nova Scotia; however, newcomer clinics are predominantly located in Halifax, and formal morphologic assessments for malaria are done in a limited number of hospital labs. Indeed, the provincial pass rate was only 80 % when malaria was first assessed in the LP3, but proficiency improved after educational sessions and with repeat testing (Table 1). To that end, we also noted an improvement in pass rates for detection and correct categorization of spherocytes, plasmacytosis, chronic lymphocytic leukemia, abnormal lymphocytes, abnormal mononuclear cells, blasts with Auer rods, and acute promyelocytic leukemia.

Even upon repeat testing, the peripheral blood cases with the lowest and most variable pass rates featured normal newborn white blood cells, plasmacytosis, and abnormal lymphocytes (Table 1). Abnormal lymphocytes are challenging to recognize [2], 7], 8], and diagnostic subcategorization requires supporting ancillary studies, such as flow cytometry [9]. So, although it is possible to further subclassify abnormal lymphocytes morphologically as hairy cells, villous lymphocytes, or Sézary cells, the proficiency expectation is limited to identifying when abnormal lymphocytes are present per the provincial peripheral blood morphology SOP.

In addition to conveniently distributing the case material upon which to base our proficiency testing, the CellaVision Proficiency Software automatically analyzed and reported pass rates for individual MLTs and their respective hospital sites. While the CellaVision Proficiency Software allowed us to ensure continuous quality improvement in the province’s peripheral blood morphology services through ongoing education, it also highlighted the practical value of assessing and maintaining competency. To that end, it was determined that some hospital labs did not see a sufficient volume and breadth of peripheral blood morphology cases to maintain technical proficiency. Between 2017 and 2022, the number of technologists performing microscopy services in Nova Scotia decreased from 213 to 130, while the number of labs offering these services decreased from 14 to 10 (Figure 1).

Our experience with the CellaVision Proficiency Software has been very positive. It allowed us to establish an effective proficiency assessment program across multiple geographically distributed sites and deliver meaningful educational sessions on specific peripheral blood findings. We hope future iterations of the software allow more than one administrator profile so that multiple users can undertake the organizational tasks of the assessment program. Should the opportunity arise, we would also welcome the incorporation of body fluid and bone marrow aspirate assessments into the proficiency software to further enhance our continuous quality improvement activities.