Refining interpretation of transcutaneous bilirubin measurement in newborns born late preterm

BACKGROUND

Transcutaneous bilirubin (TCB) monitoring is widely used for jaundice screening in the newborn period. Limited data exists on adjusting TCB for bias in late preterm infants. The objective of this study was to determine the median bias between transcutaneous bilirubin and total serum bilirubin levels in newborns born at 35-36 weeks' gestation.

METHODS

This was a retrospective cohort study of late preterm infants born at 35-0/7 to 36-6/7 weeks' gestation who were admitted to a level III neonatal intensive care unit from May 2018 to February 2020. Transcutaneous and total serum bilirubin levels were assessed within 2 h of each other during the first 60 h of life. Bland-Altman plots were used to evaluate transcutaneous bilirubin bias. Bilirubin risk stratification based on age (in hours) was done using an adaptation of the Bhutani nomogram for transcutaneous, adjusted transcutaneous, and total serum bilirubin measurements.

RESULTS

The median bias between transcutaneous and total serum bilirubin bias was 2.4 mg/dL (IQR 1.7-3.4, 95% CI 2.2-2.7). The kappa statistic demonstrated slight agreement between the unadjusted transcutaneous bilirubin and total serum bilirubin (k = 0.033, p = 0.194. The kappa statistic demonstrated fair agreement between an adjusted transcutaneous bilirubin (subtract 1 mg/dL) and total serum bilirubin (k = 0.298, p < 0.0001) and moderate agreement between another adjusted transcutaneous bilirubin (subtract 2 mg/dL) and total serum bilirubin (k = 0.430, p < 0.0001).

CONCLUSION

In a single center study of late preterm infants, transcutaneous bilirubin systematically overestimated the total serum bilirubin level. Subtracting 1 mg/dL from the transcutaneous bilirubin identified infants with total serum bilirubin levels in the high or high intermediate risk range. Adjusting the transcutaneous bilirubin prior to risk stratification may reduce unnecessary blood draws for total serum bilirubin. Studies of racially and ethnically diverse newborns using various transcutaneous bilirubin meters are needed prior to broad application of the adjusted transcutaneous bilirubin approach.

Profound Hypotonia and Respiratory Failure due to Suspected Nemaline Myopathy in a Preterm Infant

Congenital myopathies, such as nemaline myopathy, may present with hypotonia and respiratory failure in the neonatal period. Respiratory function can be further compromised in affected infants by the development of chylous effusions. We present the case of a preterm male infant born at 32 ^6/7 weeks' gestation, who was profoundly hypotonic and required intubation at birth. His clinical course progressed from acute to chronic respiratory failure with mechanical ventilation dependence. He developed bilateral chylous pleural effusions during the newborn period. Whole exome sequencing identified an ACTA1 gene mutation leading to the presumed diagnosis of nemaline myopathy. This case highlights the need to include congenital myopathies in the differential for a preterm newborn with hypotonia and respiratory failure.