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.