In a world that demands meticulous attention to detail and accuracy, the speciality of hematology is certainly no exception. The accuracy of platelet (PLT) estimates from peripheral blood smears is essential for reliable reporting. Presence of PLT clumps can introduce uncertainty, compromising the reliability of numerical estimates generated by automated whole blood analyzers. To address this, an effective system should be able to detect and identify PLT clumps with a sensitivity approaching 100%.
Microscopic examination plays a crucial role in identifying PLT clumps, with varying sensitivities based on how thoroughly the review is conducted. By concentrating on the feathered edge and the readable area of smears, a sensitivity of 99% can be achieved. Extending the examination to encompass both lateral edges, along with the feathered edge and readable area, increases the sensitivity to 100%. Therefore, it is important for laboratory technologists to examine, at the very least, the feathered edge and readable area of each peripheral blood smear.
Research conducted by Gulati et al. who collected 102 blood samples from 79 patients, revealed that the highest sensitivity of 82.8%, was achieved when reviewers expanded their examination for PLT clumps and fibrin strands to encompass the entire white blood cell (WBC) screen and the complete PLT screen, covering all nine sections. The sensitivity of detection of platelet clumps dropped to 40.4% when the user looked for clumps or fibrin strands in the WBC display only. In their analysis of the distribution of PLT clumps on various segments of the peripheral blood smear, there was a 100% positive yield when examining all three fields (feathered edge, readable area, and lateral edges) for PLT clumps. Furthermore, examining two areas—the feathered edge and the readable area—resulted in a positive yield of 99%, while examining only the feathered edge yielded 85.3% for PLT clumps.1
This approach demonstrates significantly greater effectiveness compared to the flagging efficiencies reported for PLT clumps in automated whole blood analyzers. If clumps are present, the automated platelet count is often unreliable and consequently not reportable.Previous automated digital microscopes fail to identify2 many of the specimens containing platelet clumps due to their narrow field of view, rendering manual microscope reviewing of samples with CBC-derived thrombocytopenia essential. Traditional “cell-locating” digital systems although now available with a feathered edge function, may only be able to identify large platelet clumps at 10X magnification or 50X magnification.3 These technologies still fall short of the 100 X magnification within the full slide context needed for the identification of smaller platelet clumps,4 or the identification of significant number of red cell fragments/bacteria or fungi (frequently associated with falsely high platelet counts) and significant number of giant platelets (often associated with falsely low platelet counts) within the context of the slide’s full field of view.
Scopio Labs’ revolutionary technology uses computational photography to provide unprecedented images of vast numbers of cells, including the monolayer and the feathered edge. Unlike conventional systems that create only snapshots of the digital scan, Scopio’s Full-Field technology provides a remote reviewer with both the full context of the PBS and the ability to zoom in on any cell or group of cells at 100X magnification. The monolayer and feathered edge are all there, and the reviewer can examine any detail, anywhere on the scan.
In the quest for accurate PLT estimates, a thorough and detailed microscopic examination is essential, with a keen focus on multiple aspects of the smear. As technology advances and our understanding deepens, the commitment to refining our processes ensures that laboratories can confidently provide precise and reliable information. Embracing these methodologies and technologies not only enhances current practices but also paves the way for enhanced patient-centered care.
References
1. Gulati G, Uppal G, Florea AD, Gong J. Detection of Platelet Clumps on Peripheral Blood Smears by CellaVision DM96 System and Microscopic Review. Lab Med. 2014;45(4):368-371. doi: 10.1309/LM604RQVKVLRFXOR
2. Katz BZ, Feldman MD, Tessema M, Benisty D, Toles GS, Andre A, et al. Evaluation of Scopio Labs X100 Full Field PBS: The first high-resolution full field viewing of peripheral blood specimens combined with artificial intelligence-based morphological analysis. Int J Lab Hematol. 2021;43(6):1408-1416. doi: 10.1111/ijlh.13681 https://onlinelibrary.wiley.com/doi/full/10.1111/ijlh.13681
3. Cellavision. Releasing digitized feathered edge Posted 17 Jan 2024.. https://www.cellavision.com/CellaVision-feathered-edge-release?utm_source=linkedin&utm_medium=social&utm_campaign=feathered_edge [cited 4 February 2024)
4. 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. http://dx.doi.org/10.3343/alm.2013.33.1.1
