Non-invasive bilirubin measurement in neonatal care: limits and opportunities

Key words: Bilirubin, Neonatal jaundice, Hyperbilirubinemia, Bilirubinometer

Background - Besides traditional bilirubin measurement methods, in the past few years transcutaneous measurement has become popular in Neonatal Care Units, as it is easy to use and painless. However, transcutaneous bilirubinometers are currently limited to a screening method for hyperbilirubinemia and are not recommended in newborns exposed to phototherapy.
Objective - The objective of this study is to explore the accuracy of a transcutaneous bilirubinometer by examining its performance both in term and preterm infants for jaundice screening, as well as during phototherapy sessions.
Methods - Model JM-105 Dräger is the bilirubinometer tested in the present research. Transcutaneous and serum measurements were performed simultaneously and eventually analysed.
Results - The bilirubinometer was tested on 116 newborns (gestational age ≥ 26 weeks). 158 paired samples were obtained, 35 of which during phototherapy. Comparison of serum and transcutaneous measurements showed a correlation of 0.85 and 0.89, in term and in preterm infants respectively.
Conclusions - The bilirubinometer JM-105 can be considered a reliable screening tool. Serum confirmation should be obtained if transcutaneous bilirubin levels exceed 11 mg/dl. In neonates exposed to phototherapy, the skin surfaces that are usually unexposed to light, such as the back in case of overhead spotlights and the inguinal region covered by the diaper in case of whole body exposure, may save these patients from frequent blood sampling. However, given the limited number of premature infants and phototherapy patients involved in the present study, the results obtained in these settings should be considered preliminary, and may be eventually verified with a higher number of cases.