Transcutaneous bilirubin in predicting hyperbilirubinemia in term neonates

Objective. To assess the utility of 24 and 48 hours transcutaneous bilirubin (TcB) index for predicting subsequent significant hyperbilirubinemia in healthy term neonates. Methods. TcB indices were obtained for healthy, breastfed, term AGA newborns at 24 +/- 2, 48 +/- 2 and subsequently at intervals of 24 hours. Neonates with illness, on treatment and positive Direct Coomb's test were excluded. Serum bilirubin levels were obtained whenever indicated. Neonates having serum bilirubin >= 17 mg/dL were considered as significant hyperbilirubinemia. The 24 and 48 hour TcB indices, as risk predictors for such hyperbilirubinemia were determined. Results. Study included 461 healthy term neonates. The mean birth weight was 2949 (390) gm and mean gestation of 38.6 (1.1) weeks. Eight one (17.6%) had significant hyperbilirubinemia. Of 461, 135 (29.3%) had TcB index < 5 at 24 hours and 200(43.3%) had index < 8 at 48 hours. None of them had later hyperbilirubinemia (100 % negative predictive value). Significant hyperbilirubinemia increased from 8.1% to 76.4% as 24 hours TcB index raised from 5 to 9 and from 10.4 % to 83.7% as 48 hour TcB index raised from 8 to 11. Sensitivity and specificity were optimised at TcB value of 7(risk: OR=26.8, 95%Cl: 13.9-51.5) at 24 hours and 10 (risk: OR= 17.1, 95%Cl 8.9-32.9) at 48 hours. C-statistics for 24 and 48 hour measurements are 0.838 and 0.836 respectively. Conclusion. The 24 and 48 hour TcB indices are predictive for subsequent significant hyperbilirubinemia and can guide clinician in early discharge of healthy term newborns.