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.
Keywords: Phototherapy; bilirubin; jaundice; neonate; transcutaneous bilirubin.