Refining interpretation of transcutaneous bilirubin measurement in newborns born late preterm

Jaundice screening in the newborn period is mostly done with Transcutaneous bilirubin (TCB) monitoring. However, there are very less data on adjusting TCB for bias in late preterm infants.

A recent study determined the median bias between transcutaneous bilirubin and total serum bilirubin levels in newborns born at 35–36 weeks’ gestation.

The study included late preterm infants born at 35–0/7 to 36–6/7 weeks’ gestation and admitted to a Level III neonatal intensive care unit. The infants were assessed for Transcutaneous and total serum bilirubin levels within 2 h of each other during the first 60 hours of life. Bland–Altman plots were employed to evaluate transcutaneous bilirubin bias. Bilirubin risk stratification based on age (in hours) was carried out using an adaptation of the Bhutani nomogram for transcutaneous, adjusted transcutaneous, and total serum bilirubin measurements.

The results were as follows-

• The median bias between transcutaneous and total serum bilirubin bias was found to be 2.4 mg/dL. 
• The kappa statistic showed-
• Slight agreement between the unadjusted transcutaneous bilirubin and total serum bilirubin; 
• A fair agreement between adjusted transcutaneous bilirubin (subtract 1 mg/dL) and total serum bilirubin; 
• Moderate agreement between another adjusted transcutaneous bilirubin (subtract 2 mg/dL) and total serum bilirubin.

Thus, in late preterm infants, transcutaneous bilirubin systematically overestimates the total serum bilirubin level. Subtracting 1 mg/dL from the transcutaneous bilirubin can identify infants with total serum bilirubin levels in the high or high intermediate risk range. 

Adjusting the transcutaneous bilirubin before risk stratification may lessen unnecessary blood draws for total serum bilirubin. 

Further, studies of racially and ethnically diverse newborns using various transcutaneous bilirubin meters are warranted before broad application of the adjusted transcutaneous bilirubin approach.

Akuamoah-Boateng G,Stetson RC,Karon BS, Brumbaugh JE. Refining interpretation of transcutaneous bilirubin measurement in newborns born late preterm. Pediatrics and Neonatology. 2022. DOI:https://doi.org/10.1016/j.pedneo.2022.05.003