Transcutaneous bilirubin levels in newborns <35 weeks’ gestation

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.