Correlation of transcutaneous bilirubin and serum bilirubin concentration in term and late preterm newborns

Abstract

Objective: Neonatal jaundice is a common condition requiring evaluation and treatment for most newborns. However, kernicterus is just a “tip of the iceberg” of bilirubin-induced neurologic dysfunction. The objective of this study is to evaluate the use of a transcutaneous bilirubinometer for the detection of hyperbilirubinemia in newborns. Design and Setting: In this prospective study, we measured Transcutaneous bilirubin (TcB) concentration in clinically icteric term and late preterm babies. Total serum bilirubin (TSB) was measured if the initial TcB level was higher than the 50th centile in Bhutani's nomogram. Paired TcB and TSB results were correlated, and the mean difference was calculated. Patients: Neonates of gestational age more than 35 weeks and weighing more than 2 kg were included in this study. TcB recordings were taken in neonates who appeared clinically icteric. Results: Four hundred paired TcB and TSB measurements were taken. TcB was significantly correlating with TSB (P < 0.001) in both low-risk and medium-risk thresholds for phototherapy. TcB had a sensitivity and negative predictive value of 100% each, a specificity of 56%, and a positive predictive value of 23%. For high-risk cases, using the 75th centile as cutoff, the sensitivity and negative predictive value were reduced to 88% and 97.0%, respectively. Conclusion: TcB correlates closely with TSB concentration in neonates born after 35 weeks gestation. The rate of rise in TcB may help in identification of neonates at risk and minimizing invasive blood investigations.