Transcutaneous bilirubinometry: Influence of gestational age and measurement site

Introduction: Neonatal jaundice is the most frequently encountered diagnostic and therapeutic problem in neonates. An estimation of bilirubin is essential for decision making. Transcutaneous bilirubinometer (TcB) is a non-invasive, quick and widely used screening and monitoring tool for the estimation of serum bilirubin.

Objectives: To determine correlation and agreement between TcB and total serum bilirubin (TSB) and to verify the influence of different measurement sites for TcB estimation (forehead, sternum and abdomen) in preterm and full-term neonates.

Method: In a prospective study, 306 paired TcB-TSB samples from 306 haemodynamically stable term (150) and preterm (156) infants, up to 14 postnatal days with clinical jaundice were analysed. TcB was measured at the forehead, sternum and abdomen within 5 minutes of blood collection, by a single investigator using Dräger jaundice meter JM-103 device. Linear regression analysis and Bland-Altman plots were used to compare TcB values at each site with TSB levels.

Results: The mean ± standard deviation (SD) for gestational age, birth weight and postnatal age were: 35.22±2.56 weeks, 2017±0.59g and 96.21±68.2 hours respectively. The mean ± SD TcB at different sites were; forehead 13.46±4.32, sternum 13.33± 4.38 and abdomen 11.88 ± 4.27 mg/dl. The mean ± SD TSB was 15.59±5.93 mg/dl. TcB significantly correlated with TSB at all three measurement sites (p<0.001). The correlation coefficient (r) among the sites were: forehead: 0.88, sternum: 0.88, and abdomen: 0.86. Bland–Altman plot showed significant agreement between TcB and TSB in both preterm and term neonates at all three measurement sites.  

Conclusions: The TcB levels can accurately predict TSB in both preterm and term neonates and also at all measurement sites viz. forehead, sternum and abdomen.

Sri Lanka Journal of Child Health, 2018; 47(1): 27-32