Predictive value of umbilical cord blood bilirubin for postnatal hyperbilirubinaemia

Abstract

Aim: The study investigated the predictive value of umbilical cord serum (UCS) bilirubin for the postnatal course of bilirubinaemia in healthy term and near-term newborns.

Methods: Term appropriate-for-gestational-age (AGA; n=1100), small-for-gestational-age (SGA; n=163) and near-term infants (GA 34-36 wk; n=78) were included and separated according to their UCS bilirubin levels, starting from <20 (group 1), 20-<30 (2), 30-40 (3) and >40 (4) micromol/l. The newborns were followed for at least 5 postnatal days, and UCS bilirubin values were correlated with the development of hyperbilirubinaemia and phototherapy (PT) treatment.

Results: A clear relation between UCS bilirubin and the development of hyperbilirubinaemia was found in all three patient populations. None of the 75 AGA patients of group 1 developed postnatal bilirubin values above 300 micromol/l, whereas 0.3, 3.4 and 8.6% of the patients in groups 2-4, respectively, did so. The frequency of PT increased from 0% in group 1 up to 9.6% in group 4. For the prediction of further need of PT using a UCS bilirubin cut-off level of 30 micromol/l, we found a sensitivity of 90% and a negative predictive value of 99.1%, indicating that all patients with UCS bilirubin values below 30 micromol/l (443/1100 or 40.2%) were at a very low risk of developing dangerous hyperbilirubinaemia. Similar results were obtained in SGA children with a sensitivity of 94.1% and a negative predictive value of 98.6%. In comparison to term newborns, we generally found higher bilirubin values in preterms. A total of 6.4% of preterm children developed bilirubin values over 300 micromol/l, compared with 3% of term children, and 47.4% of preterms had to be treated with PT. Predicting the need of PT by using a UCS bilirubin cut-off level of 30 micromol/l revealed a sensitivity of 70.3% and a negative predictive value of 65.6%.

Conclusion: These data suggest that UCS bilirubin is useful in predicting the postnatal bilirubin values in term and near-term newborns. We presume that the use of UCS bilirubin values may help detect infants at low risk for postnatal hyperbilirubinaemia and minimize an unnecessary prolongation of hospitalization.