2021 update of the 2012 ICSH Recommendations for identification, diagnostic value, and quantitation of schistocytes: Impact and revisions

Abstract

In 2012, the International Council for Standardization in Haematology (ICSH) published recommendations for the identification, quantitation, and diagnostic value of schistocytes. 1 This document was prepared due to the recognized need to harmonize schistocytes reporting within national hematology societies, most notably in France 2,3 and Italy. 4 It is freely available on the ICSH website (www.icsh.org).The 2012 ICSH recommendations focused on the microscope evaluation method, specific morphologic criteria for schistocyte identification and percentage calculation, definition of a threshold value in healthy subjects.

Snakebite Associated Thrombotic Microangiopathy and Recommendations for Clinical Practice

“…Two studies from Australia and India provide evidence supporting a role for schistocyte quantitation in snakebite [28,44,55]. This is in addition to several studies on the diagnostic utility of schistocyte quantitation for the diagnosis of TMA more broadly in non-snakebite settings [54,[56][57][58][59]. Schistocytosis in snakebite is significantly predictive of the development of AKI in Australian snakebite presenting with VICC, with AKI shown in multiple studies to be the major complication of snakebite-associated TMA [44].…”

“…Microangiopathic haemolytic anaemia is defined by the presence of blood film schistocytes (black arrows). Red cell morphological changes in microangiopathic haemolytic anaemia may also include micro-spherocytes (red arrows), which are secondarily derived from schistocytes, as defined by the International Council for Standardization in Haematology [53,54]. Derived from Noutsos et al [55].…”

“…Microscopists who are calibrated and trained can perform the procedure with reasonable inter-and intra-observer agreement. Cases in which there is a clinical suspicion of TMA should undergo serial blood film examinations over the first 24 h [54].…”

“…The WHO includes peripheral blood film examination, and Wright, May-Grünwald or Giemsa staining for blood films in its model list of essential in vitro diagnostics for primary health care where a good quality microscope is available, and for all district, regional, provincial and specialised hospitals or laboratories [64]. The International Council for Standardization in Haematology have a published publicly available international consensus guideline on manual blood film schistocyte quantitation from 2012, which was recently updated in 2021 [53,54]. In addition, the WHO produces multiple written guidelines and illustrated bench aids with respect to manual blood film methods and the identification of abnormal red cell morphology [65,66].…”

Combining imaging flow cytometry and machine learning for high-throughput schistocyte quantification: A SVM classifier development and external validation cohort

“… 5 , 6 The state of the art in terms of schistocyte quantification is currently based on morphological evaluation of RBCs by the analysis of blood smears after May Grümwald Giemsa coloration. 4 , 7 , 8 The International Council for Standardisation in Haematology (ICSH) guidelines defines specific positive morphological criteria and typical RBC shapes (keratocytes, helmet cells, crescents, and triangles) and recommends counting schistocytes among at least 1,000 RBCs 7 , 8 to significantly improve the standardisation of their quantification. Nonetheless, the schistocyte count is probably among the most important parameters to be automated.…”