Clinician-Ordered Peripheral Smear Review by a Pathologist Has Low Clinical Utility—A Reference Laboratory Perspective

Abstract

Background Clinician-ordered peripheral smear review by pathologist (CPSR) is commonly ordered and has been recommended for decades. However, the clinical utility of this labor-intensive test in the reference laboratory has not been examined. The objective of this study is to assess hematologic abnormalities identified in CPSR orders and to correlate them with complete blood count (CBC) and laboratory-derived smear review (LDSR) in the reference laboratory. Methods Two hundred consecutive CPSRs with corresponding CBCs from April 2023 were run by Sysmex® XN-11 analyzers, and their peripheral smears were examined by a board-certified hematopathologist. Hematologic abnormalities of CPSRs were assessed, and the correlation between CPSR and CBC/LDSR was reviewed. Results Nearly one-third of CPSRs (29%) had normal peripheral smears and CBCs. The majority of CPSRs showed nonspecific quantitative abnormalities. When compared against CPSR results, LDSR criteria identified 100% of hematologic abnormalities appropriately. Samples that were not flagged for review by LDSR rules were also reviewed (n = 174) to rule out clinically meaningful false negatives. One minor discrepancy (0.6% of cases) of small platelet aggregates was observed in a patient with a reported platelet count of 139 K/uL that was missed by the LDSR process. Conclusions In the reference laboratory setting, our findings demonstrate that LDSR adequately detects significant hematologic abnormalities and, therefore, CPSR should be discontinued.