Haematological scoring system- a diagnostic tool for neonatal sepsis. How reliable is it?

Introduction: Neonatal septicaemia is the important cause for mortality and morbidity. Early diagnosis helps in timely intervention and favorable outcome. Although blood culture is gold standard, it has low sensitivity and delays the diagnosis. Hence formulation of rapid diagnostic tools that can indicate sepsis at earlier stage is important. Objective: To evaluate performance of each parameter in the Hematological scoring system (HSS) in diagnosis of neonatal sepsis. Materials and Methods: Blood samples from 130 clinically suspected neonates were subjected to sepsis screening tests. Differential count was performed on the peripheral smear to obtain immature cell count. Hematological scoring was performed. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated for each of the parameter with blood culture as Gold Standard. Results: Out of 130 sepsis suspected neonates, 35.4% showed culture positivity. Total polymorphonuclear count had highest sensitivity (89.6%) and NPV (84.3%) and immature to mature PMN count (I:M) >0.3 had highest specificity (100%)and PPV(100%). HSS with the combination of two test being positive (score ?2) gave good sensitivity (100%) and NPV (100%); but low specificity (54.7%) and PPV (54.7%). Specificity and PPV increased with increase in the HSS. Conclusion: No parameters can be taken alone as indicator of sepsis. Total PMN count was the sensitive indicator but lacks specificity. HSS score of <2>