Transcutaneous bilirubin measured on protected skin during phototherapy in term and preterm neonates

Transcutaneous bilirubin (TCB) measurement is a simple, painless, and time-saving alternative for the assessment of TSB (total serum bilirubin) levels. However, TCB measurements obtained during phototherapy can yield inaccurate results. We evaluated the effectiveness of TCB measurements obtained from protected skin areas in patients who underwent phototherapy.

This prospective study included neonates delivered at a gestational age of ≥34^0/7 weeks. TCB measurements were performed at the forehead and the lower end of the sternum using a JM-105 device. Simultaneously, blood samples were collected to determine TSB levels. During phototherapy, the forehead was covered with a photo-opaque patch. TSB and TCB were measured before, during, at the end of, and after phototherapy.

In total, 200 neonates, including 110 (55 %) term and 90 (45 %) late preterm infants, were enrolled. Of these neonates, 162 (81 %) were Turkish while 38 (19 %) were refugees from Syria and Iraq. Notably, no statistically significant differences were observed in the TSB and TCB values between the Turkish and refugee groups (p > 0.05). Bland-Altman analysis was conducted between the TCB values obtained from the covered forehead area and TSB values; the analysis revealed moderate, high, and excellent agreements for the first bilirubin measurement and at the end of phototherapy, before phototherapy, and for the second and rebound bilirubin measurements, respectively. Regarding intraclass correlation coefficients, values >0.95, 0.94-0.85, 0.84-0.70, and < 0.7 indicated perfect, high, moderate, and unacceptable compatibilities, respectively. Although a significant association was observed between pre-phototherapy TCB obtained from the sternum and TSB levels, no significant associations were observed during phototherapy.

Our findings indicate that the consistency observed between TCB measurements obtained from the protected skin areas and TSB values can be used to monitor phototherapy effectiveness, particularly in late preterm/term infants and those with darker skin tones. Furthermore, this approach can aid in guiding decisions related to treatment termination, evaluating rebound bilirubin levels, minimizing costs, and providing a less invasive testing option.