Correlation between transcutaneous and serum bilirubin in preterm infants before, during, and after phototherapy

Background: Transcutaneous bilirubinometry (TcB) is routinely used to monitor jaundice in term and near-term infants. However, before 35weeks gestation, the technique has not been widely adopted.Aim: The aim of this study is to study the correlation between TcB and total serum bilirubin (TsB) before, during, and after phototherapy in preterm infants born before 35 weeks' gestation.Methods: Jaundice was monitored in infants born before 35 weeks' gestation by simultaneous measurements of TsB and TcB assessed by a Drager Jaundice Meter JM-103 (Draeger Medical, Inc., Telford, PA).Results: About 588 pairs of measurements were recorded in 86 premature infants of 26-34 weeks, weighing 618-2400 grams. The overall correlation coefficient between TcB and TsB was 0.8 (p=.001). Subset analysis revealed lower correlation in infants born before 30 weeks. TcB was consistently estimated around 1mg% lower than TsB. Neither the cause of the jaundice nor major neonatal morbidities significantly influenced the TcB-TsB correlation.Conclusions: TcB is a reliable measure of jaundice before 35 weeks' gestation with a mean under-estimation of approximate to 1mg%. TcB use may reduce unnecessary invasive blood tests.