Lack of identifiable risk factors for kernicterus.

In recent years kernicterus at autopsy has been observed in sick premature infants in the absence of markedly elevated levels of serum bilirubin. Potentiating factors have been suggested to explain kernicterus in such a setting. In order to establish which factors are associated with increased risk for kernicterus in these small babies, this retrospective matched control study was undertaken. Thirty-two infants with kernicterus at autopsy were matched for gestational age, birth weight, length of survival, and year of birth to 32 control infants without kernicterus. Multiple historical, clinical, and laboratory factors were compared, including therapy, sepsis, hypothermia, asphyxia as reflected by Apgar score, hematocrit, acidosis, hypercarbia, hypoxia, hypoglycemia, and hyperbilirubinemia. No statistically significant differences between the kernicteric and nonkernicteric infants were demonstrated for any of these factors, including peak total serum bilirubin levels. Multivariant analysis also failed to determine a group of factors associated with increased risk for kernicterus. It was not possible to separate those infants with and without kernicterus at autopsy on the basis of the clinical factors evaluated.