Role of complete blood count in the diagnosis of culture-proven neonatal sepsis: a systematic review and meta-analysis

Objective Neonatal sepsis is a significant cause of morbidity and mortality, particularly in preterm infants. Despite its routine use in adults, the diagnostic utility of complete blood count (CBC) in neonatal sepsis remains debated. This systematic review and meta-analysis aimed to evaluate the diagnostic accuracy of CBC parameters for neonatal sepsis. Methods This review was registered at PROSPERO (CRD42023476510). MEDLINE, Embase, CINAHL and the Cochrane Library were searched from database inception to 28 October 2024. Observational studies of neonates with sepsis, published in English, were included. Pooled diagnostic accuracy metrics were calculated for CBC parameters, including the white cell count (WCC), neutrophil count and immature-to-total neutrophil ratio (ITR). Bias was assessed using a modified QUADAS-2 tool. Results Functional CBC parameters like ITR and mean neutrophil volume (MNV) showed moderate diagnostic accuracy. Pooled analysis revealed that an ITR >0.20 had 66.3% sensitivity and 85.4% specificity for neonatal sepsis. MNV also showed promising diagnostic utility, but substantial heterogeneity across studies (I2>0.80) limited its generalisability. Traditional parameters like the WCC and platelet count had lower diagnostic accuracy. Conclusions The CBC is a rapid, cost-effective test requiring minimal blood volume, making it a practical adjunct in neonatal diagnostics. Functional parameters like ITR and MNV show the potential to complement existing approaches but are insufficient as stand-alone diagnostic tools. Further research is needed to validate their clinical utility and address heterogeneity in study designs.