Transcutaneous bilirubin levels in newborns <35 weeks’ gestation

Abstract

Objective:

In infants <35 weeks’ gestation, we sought to define the transcutaneous bilirubin (TcB) levels at which a total serum bilirubin (TSB) level suggesting the need for phototherapy is unlikely to occur and a TSB measurement can, therefore, be avoided.

Study Design:

Nursing staff performed 896 TcB measurements within 1 h of a TSB on 225 neonates 26 0/7–34 6/7 weeks’ postmenstrual age (PMA). Generalized linear models were fit with generalized estimating equations (GEEs) to model the probability of having a TSB level at or above the phototherapy initiation cutpoint as a function of the TcB; these methods allow for multiple tests per infant.

Results:

The mean difference between TcB and TSB measurements was <1 mg dl⁻¹ for each PMA category. When the TcB was at least 3 mg dl⁻¹ below the TSB cutpoint for phototherapy, there was a ⩾98% probability that the TSB was not at, or above, the recommended phototherapy level. The single exception to this was a phototherapy level of 6 mg dl⁻¹ for infants of 28 0/7–29 6/7 weeks’ PMA, where a TcB of 4 mg dl⁻¹ below the phototherapy level (ie a TcB ⩽2 mg dl⁻¹) was necessary to achieve ⩾98% probability.

Conclusion:

Our data support the use of routine TcB screening for infants 28–34 6/7 weeks’ gestation. TcB screening in the neonatal intensive care unit can identify infants who require a TSB to confirm or exclude the need for phototherapy.