Transcutaneous bilirubin estimation in extremely low birth weight infants receiving phototherapy: a prospective observational study

Vidit Bhargava, Daniel Tawfik, Bruce Niebuhr, Sunil K. Jain

Measurement of transcutaneous bilirubin (TcB) is a quick, reliable and painless method to guide management of hyperbilirubinemia. Studies in term and late preterm infants have found that TcB measurements from covered areas (TcB-C) during phototherapy (PHT) co-relate well with serum bilirubin levels. Limited data exists in extremely low birth weight (ELBW) infants. In this prospective observational study, an opaque patch was placed on the back of an ELBW infant prior to initiation of PHT. TcB-C and TcB-E (TcB from exposed area) levels were measured at birth and at 24-h intervals for 5 days. Total serum bilirubin (TSB) levels were also measured within 30 min of obtaining TcB levels. A Wilcoxon signed rank test was used for data analysis. A mixed effect model was used to adjust for repeated measurements over time. The p value < 0.05 was considered significant. A total of 19 infants were enrolled in the study, with a mean gestational age of 26 ± 2 weeks and mean weight 827 ± 127 g. The difference between TcB-C and TSB was 2.68 ± 2.41 mg/dl (mean ± SD, p <  0.001). In contrast, the difference between TcB-E and TSB was - 0.51 ± 1.74 mg/dl (p = 0.02). TcB-C consistently overestimates TSB, while TcB-E consistently underestimates TSB. During PHT exposure, TcB-C does not correlate with TSB values in ELBW infants. TcB-C levels cannot be used as a surrogate for TSB measurement in ELBW infants.