Accuracy of transcutaneous bilirubinometry in term infants after phototherapy: a prospective observational study

Objective: To test the accuracy of transcutaneous bilirubinometry (TcB) in neonates 12 h after discontinuing phototherapy. Study design: In a prospective study of 91 neonates at ≥35 weeks of gestation, paired measurements of total serum bilirubin (TSB) and TcB were obtained 12 h after discontinuation of phototherapy. TcB measurements were obtained on the uncovered skin of the sternum and the covered skin of the lower abdomen. Bland–Altman plots were used to evaluate agreement between TSB and TcB. Results: TcB was found to systematically underestimate TSB on both covered and uncovered skin. The smallest but statistically significant difference between TSB and TcB was found on the covered lower abdomen (–1.03, p < .0001) compared with the uncovered skin of the sternum (–1.44, p < .0001). The correlation between TSB and TcB was excellent on both covered (r = 0.86, p < .001) and uncovered skin (r = 0.90, p < .001). Bland and Altman plots showed poor agreement between TcB and TSB. Conclusions: This study demonstrated excellent correlation between TcB and TSB 12 h after phototherapy but poor TcB–TSB agreement. TcB cannot be reliably used in neonates exposed to phototherapy.