The forehead is a better site than the sternum to check transcutaneous bilirubin during phototherapy in sick infants

Background To confirm the accuracy of transcutaneous bilirubin (TcB) in the neonatal intensive care unit both with and without phototherapy, and compare forehead and sternum as the TcB assessment site. Methods We simultaneously assessed the total serum bilirubin (TSB) and TcB at the forehead and sternum, using a JM-103 bilirubinometer. We analyzed the correlation between the TSB and TcB assessed at the forehead and sternum, with measurements classified as 'without phototherapy' (before phototherapy and > 24 hours after phototherapy discontinuation) and 'with phototherapy' (after 24 hours of phototherapy). Results There were 1,084 paired forehead and sternum TcB measurements, with the corresponding TSB measurement, from 384 infants. Their mean gestational age of 35.4 +/- 3.2 weeks (62% were preterm) and a mean birth weight of 2434 +/- 768 grams, and TSB was 6.61 +/- 3.56 mg/dL. Without phototherapy, TcB values at the forehead and sternum were correlated well to the TSB value (r = 0.925 and 0.915, respectively). With phototherapy, TcB values at the forehead and sternum were significantly correlated with the TSB value, but TcB at the forehead (r = 0.751) was a better match to the TSB than was TcB at the sternum (r = 0.668). Additionally, Bland-Altman plots showed a greater degree of underestimation of the TSB by TcB at the sternum with phototherapy. Conclusions TcB was more accurate in infants not receiving phototherapy. During phototherapy, it is better to assess TcB at the forehead rather than at the sternum.