Accuracy of Transcutaneous Bilirubin Determinations in Neonates: The Effect of Gestational Age, Time and Site of Measurement

Objective: To assess the accuracy of transcutaneous bilirubin (TcB) measurements in neonates, in relation to gestational age (GA), time (postnatal hour) and site (forehead, sternum, knee) of measurements.

Hypothesis: Using (or combining) different sites for TcB determination might improve the accuracy of TcB in relation to the time of measurement and the GA of the neonate.

Methods: The study will include neonates >32 weeks' gestation cared for in the well-baby nursery and NICU of the University Hospital of Patras, from September to December 2011. Data such as sex, gestational age, gestation and perinatal information, mother's and infant's ABO group and Rh, G6PD deficiency, Coombs test, type of delivery and complications, birthweight, postnatal medications and interventions, type and volume of feeding, and extension of jaundice, will be collected.

TcB measurements will be performed using the BiliCheck bilirubinometer (according to the standard protocol) at 3 different sites: forehead, sternum and knee. Total serum bilirubin (TSB) values will be obtained using the heel stick technique, and measurements will be performed by a direct spectrophotometric device (Unistat bilirubinometer, Richert, Depew, NY). The accuracy of the device has been validated previously. TSB measurements will be performed within 5 minutes of the TcB measurements.

At each occasion TcB measurements (3), the corresponding TSB value, the time of measurement (postnatal hours), and the actual weight will be noted.

Statistics: The agreement between TcB and TSB values will be assessed using the Bland-Altman % method. The independent and joint effects of GA and time of measurement on bias will be evaluated by multivariate regression analysis.