10 Severe Neonatal Hyperbilirubinemia: Cause for Concern?

Abstract

Although severe neonatal hyperbilirubinemia in the term neonate and bilrubin encephalopathy is rare, it is associated with significant morbidity. A number of reports have been published in recent years of bilirubin encephalopathy in term neonates who appeared to be healthy and breast-fed with no evidence of hemolytic disease (Maisels 1995, Ebbesen 2000). Some risk factors are known to be associated with severe hyperbilirubinemia in the newborn and include: jaundice in the first 24 hours of life, previous sibling with jaundice, and gestational age of 35 to 38 weeks (Dennery et al 2001). Additional risk factors include Rh and ABO incompatibility and Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency. Attempts to better quantify the frequency, etiologies and risk factors for neonatal hyperbilirubinemia would be of value prior to identifying strategies for risk reduction. Our objective was to obtain epidemiological data about severe neonatal hyperbilirubinemia in order to develop prevention strategies for this condition. Data on term infants 60 days of age or less with unconjugated hyperbilirubinemia was collected from July 2002 to present through the Canadian Pediatric Surveillance Program. Criteria for inclusion in this study included: 1) peak serum total bilirubin >425 μmol/L or 2) neonatal exchange transfusion. Infants who had exchange transfusions for well-documented Rh isoimmunization disease or were less than 36 weeks of gestational age were excluded. After 16 months of surveillance 220 cases of severe neonatal hyperbilirubinemia were reported. Of these, 148 were confirmed, 33 were duplicates or discarded, and 39 are still under review. In only 47 cases was the cause of the hyperbilirubinemia identified. The etiologies included ABO incompatibility (n=28), G6PD deficiency (n=13), other antibodies (n=4), and unstable hemoglobin (n=2). The range of bilirubin reported was from 156 to 731 μmol/L. 37 of the neonates required exchange transfusion, while all neonates were treated with phototherapy. 6 neonates had documented hearing loss and 3 had seizures prior to discharge from hospital. This study shows that severe neonatal hyperbilirubinemia continues to occur in term neonates with significant morbidity. In the majority of cases the underlying etiology could not be identified, which could partly be attributed to incomplete evaluation at the time of presentation. This finding highlights the importance of a complete hematological workup for such children prior to discharge such as a screen for blood group, Coomb's testing, peripheral smear, and a screen for G6PD. Further testing including a hearing assessment and close pediatric follow-up is also likely to be beneficial.