Prediction of significant hyperbilirubinemia in term neonates by early non-invasive bilirubin measurement

Background: Neonatal jaundice is a common problem. We evaluated the utility and best cut-off values of 24 and 48-hour transcutaneous bilirubin indices (TcBI) in predicting subsequent significant hyperbilirubinemia and evaluated various associated maternal and fetal risk factors. Methods: TcBI at 24 and 48 hours and serum bilirubin levels at 72 hours of age were obtained for healthy, term, appropriate for gestational age neonates. Neonates with prematurity, birth weight <2500 g, ABO or Rh incompatibility, onset of clinical jaundice <24 hours, clinical suspicion of septicemia, positive pressure ventilation at birth, admission in neonatal intensive care unit and contraindications for BiliChek were excluded. Twently-four and 48-hour TcB indices were assessed as predictors of subsequent hyperbilirubinemia, defined as serum bilirubin >17 mg/dL after 72 hours of life and various cut-offs, and were evaluated by calculating sensitivity, specificity and predictive values. Results: Of 500 newborns, 4.6% had significant hyperbilirubinemia, 27% had TcBI (mg/dL) <5 at 24 hours, and 27.4% had TcBI <8 at 48 hours. None of them had subsequent hyperbilirubinemia (100% negative predictive value). The percentage of newborns with subsequent hyperbilirubinemia increased from 3.4% to 13.2% as their 24-hour TcBI increased from 6 to above 9 mg/dL and from 4.2% to 7.4% as their 48-hour TcBI increased from 8 to above 11 mg/dL. The best cut-off value was TcBI (mg/dL) 7 (odd ratio=4.86, 95% confidence interval: 1.66-15.22) at 24 hours and 10 (odd ratio=2.87, 95% confidence interval: 1.04-8.29) at 48 hours. Area under the receiver operating characteristic curve for 24- and 48-hour measurements was 0.750 and 0.715, respectively. Maternal premature rupture of membranes, deep transverse arrest, post-date pregnancy, and fetal distress were significant risk factors for hyperbilirubinemia. Conclusions: Twenty-four and 48-hour TcB indices are good predictors of subsequent hyperbilirubinemia. Twenty-four-hour TcBI had better predictive ability than 48-hour TcBI.