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

Abstract

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. 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. 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. 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.