Neonatal sepsis: Role of a battery of immunohematological tests in early diagnosis

BACKGROUND AND OBJECTIVE: Worldwide, many neonates with sepsis die due to lack of early diagnosis. In this study we attempt to analyze the value of various immunological and hematological parameters, singly and in combination, for the diagnosis of neonatal sepsis, with the aim being to formulate guidelines for the early diagnosis of the condition. MATERIALS AND METHODS: In this prospective study, 62 patients having clinical suspicion of neonatal sepsis were evaluated with a battery of investigations. Neonates admitted for other causes and without clinical suspicion of sepsis were selected as controls (n=40). The tests included blood culture, hemoglobin level, total and differential blood count, absolute neutrophil count, ratio of immature to total neutrophil count (I/T ratio), micro-erythrocyte sedimentation rate (m-ESR), C-reactive protein (CRP), platelet count, serum IgM level, and plasma fibrinogen level. Patients were divided into proven cases (positive blood culture) and probable cases (negative blood culture). RESULTS: Positive blood culture was seen in 38 cases (61.3%). Raised m-ESR (>8 mm in the first hour) was seen in 63.2% of proven and 66.7% of probable cases. I/T ratio of ≥0.2 was seen in 63.2% and 58.3% of proven and probable cases, respectively. Morphological changes in neutrophils were detected in 68.4% of proven cases and 91.7% of probable cases. Positive CRP test (≥6 mg/l) was found in 84.2% of proven cases and 100% of probable cases. Raised serum IgM, leucopenia, and neutropenia were seen in a small number of patients (11%–37%). Raised fibrinogen level (>400 mg/l) was seen in patients as well as in controls. CONCLUSIONS: The four useful tests that we identified were m-ESR, I/T ratio, morphological changes in neutrophils, and CRP; and role of these tests in early diagnosis of neonatal sepis were statistically significant (P<.05). The most sensitive test was CRP (84%) and the most specific test was m-ESR (94%). A combination of three or all of these four tests was highly specific (95%–100%).