Review and Comparison of Peripheral Blood Smear for Children with COVID-19 Compared to Non-COVID Children

Abstract

Background: Since the outbreak of COVID-19, laboratory findings, particularly patients' blood data, have been deemed crucial. This study compared peripheral blood smear changes in children with COVID-19 and controls. Methods: This cross-sectional study was conducted at Imam Hossein Pediatric Hospital in Isfahan. PBS and CBC data from 50 children with a positive PCR test or a MIS-C diagnosis were compared to a control group of 50 children hospitalized in non-infectious and non-COVID-19 wards. The data obtained from PBS and CBC, along with demographic information such as age and sex, were statistically analyzed. Findings: Children with COVID-19 exhibited higher red blood cell (RBC) counts and lower neutrophil and white blood cell (WBC) counts. Although they had more vacuolated neutrophils, the control group showed higher levels of hypersegmented neutrophils and dysplastic monocytes. The case group had normal RBC counts and low neutrophil counts, whereas the control group had low RBC counts and high neutrophil counts. Patients with positive PCR tests showed increased monocyte, eosinophil, and platelet counts. Common morphological forms observed in patients included atypical lymphocytes, large granular lymphocytes (LGL), hypersegmented and vacuolated neutrophils, toxic granulation, hypogranulation, a left shift, pseudo-Pelger-Huet anomaly, dysplastic monocytes, and schistocytes. Conclusion: Elevated RBC counts and reduced neutrophil and WBC counts in infected children, along with increased monocytes, eosinophils, and platelets in patients with positive PCR tests, as well as specific cellular forms, particularly dysplastic monocytes, and neutrophil anomalies, are instrumental in diagnosing these patients. © 2025, Isfahan University of Medical Sciences(IUMS). All rights reserved.