Coombs' testing and neonatal hyperbilirubinemia/The authors respond

Although we fully agree with Michael Sgro and colleagues regarding the need for early identification and effective management of neonatal hyperbilirubinemia, we were surprised to see their recommendation that the Coombs' test be used to screen for hyperbilirubinemia in all infants born to mothers with type O blood.1 Although the Coombs' or direct antibody test (DAT) is an important test when trying to identify the cause of neonatal hyperbilirubinemia, recent studies have shown that it has extremely limited usefulness in predicting the development of significant hyperbilirubinemia. Many strategies have been postulated as being cost-effective in preventing severe neonatal hyperbilirubinemia. We welcome the use of strategies coupling clinical suspicion of risk of hyperbilirubinemia at the time of discharge with close outpatient monitoring. Transcutaneous bilirubinometers, although very useful within a clinical context, may not always serve as a substitute for a serum bilirubin measurement when the bilirubin concentration reaches levels at which phototherapy is required.4,5 No reported strategies using transcutaneous bilirubinometers have yet been proven to be cost-effective,6 largely because the prevalence of long-term neurological sequelae of severe hyperbilirubinemia is not yet known. Given the possibility that introducing routine screening (serum bilirubin measurements, blood group typing and Coombs' testing) may have financial implications such as longer hospital stays for newborns, it is important to understand the burden of illness of severe hyperbilirubinemia and its complications in Canada, namely bilirubin-induced neurological dysfunction and kernicterus. [Thomas Newman] and [Jeffrey Maisels] referenced a Danish case-based report4 that estimated the incidence of kernicterus at 1 in 50 000 to 1 in 60 000 live births. It is important to note that this was by no means a systematic review of the Danish population. In our study, half of the infants with severe hyperbilirubinemia were born to nonwhite mothers.2 Ethnicity may be a contributing factor to severe hyperbilirubinemia, secondary to a higher incidence of glucose-6-phosphate dehydrogenase deficiency in non-white populations and a delay in recognition of jaundice owing to the babies' darker pigmentation.