Comparison of the transcutaneous bilirubinometers BiliCheck and Minolta JM-103 in preterm neonates

Aim:  To investigate the trueness and uncertainty of two transcutaneous bilirubinometers BiliCheck and Minolta JM-103 in preterm infants; establish cut-off values for the transcutaneous bilirubin (TcB) level, indicating the need for total serum bilirubin (TsB) measurement; and estimate how many blood samples could be saved. Methods:  In 133 neonates with gestational ages 28(+0) -34(+6)  weeks, 239 measurements of TcB by BiliCheck (TcB(B)) and JM-103 (TcB(M)) and of TsB were performed. Results:  Median TsB of the first samples was 160 (range, 53-293) μmol/L, whereas median TcB(B) was 12 μmol/L (8%) lower and TcB(M) 67 μmol/L (40%) lower. TcB(B) underestimated TsB for TsB ≥180μmol/L. All TcB(M) values, except one, underestimated TsB. The underestimation increased with increasing TsB. Multiple regression analysis showed that post-natal age and ethnicity were confounding factors for TcB(M); none were found for TcB(B). The uncertainty was the same for the two instruments. By using cut-off values of 70% of the phototherapy limit for TcB(B) and 35% for TcB(M), the sensitivity of the screening would be 95% and 97%, and 36% and 24% of the blood samples could be saved, respectively. Conclusion:  TcB determined with JM-103 gave values much lower than those obtained with BiliCheck. The underestimation of TsB increased with increasing concentrations. By using transcutaneous bilirubinometers in preterm neonates, 24-36% of the blood samples could be saved.