Role of manual Immature to Total Neutrophil (I/T) ratio and automated Immature Granulocyte Count (IGC) and percentage (ig%) in the early diagnosis of neonatal sepsis

Author(s): Nalika Jayasekara, Chandima Kulathilake, Saraji Wijesekara and Indira Wijesiriwardena

Background: The diagnosis of neonatal sepsis is challenging due to non-specific and subtle clinical features, low sensitivity and delay in routine laboratory tests. Current study was conducted to evaluate the role of manual Immature/Total (I/T) neutrophil ratio and automated Immature Granulocyte Count (IGC) and Immature Granulocyte percentage (IG%) in the diagnosis of neonatal sepsis. Materials and Methods: An analytical cross-sectional study was done during a period of 6 months with a sample of 55 neonates admitted to Colombo South Teaching Hospital, Sri Lanka. A combination of clinical and laboratory parameters including full blood count, C-reactive protein and blood culture were used to identify the neonates with probable sepsis. The population was subcategorized into five (5) groups and manual Immature/Total neutrophil (I/T) ratio, Immature Granulocyte Count (IGC) and Immature Granulocyte percentage (IG %) were done. Results: The sensitivity of manual I/T ratio was 93.8% and Negative Predictive Value (NPV) of 95.2%. The sensitivity for lower cut off values, IGC of 0.03 × 103/µL and IG% of 0.5% was 80% and 73.3% respectively. The NPV for above cut-off values were 25% and 0.5% respectively. The NPV was improved with higher cut-off values with 70.9% for IGC 0.3 and 70.6% for IG 3%, but sensitivity remained low with 40% and 33.3% respectively. Conclusion: Manual I/T ratio remain as a useful diagnostic tool in diagnosing and excluding neonatal sepsis with a very good sensitivity and NPV. However, further studies and well-defined reference intervals are required in automated IGC and IG%.