Accuracy of transcutaneous bilirubin measurement in newborns after phototherapy.

OBJECTIVE: We tested the accuracy of transcutaneous bilirubin (TcB) measure in newborns undergoing phototherapy. STUDY DESIGN: In a prospective study of 150 term Caucasian neonates, 255 measurements of total serum bilirubin (TSB) and TcB concentration were obtained 2 h after discontinuing phototherapy. TcB measurements obtained on the forehead, sternum, abdomen and covered lower abdomen were statistically compared with the corresponding TSB. RESULT: TcB consistently underestimated TSB levels significantly. The smallest but significant difference between TSB and TcB was found on the lower abdomen. The correlation between TSB and TcB was found to be moderately close (r=0.4 to 0.5). TcB measurements were inaccurate, regardless of phototherapy technique (Bilibed, conventional phototherapy). CONCLUSION: Phototherapy significantly interferes with the accuracy of transcutaneous bilirubinometry. TcB measurements performed 2 h after stopping phototherapy were not reliable, even if they were carried out on the unexposed body area. TSB assessment remains necessary, if treatment of hyperbilirubinemia is being considered.