KERNICTERUS: HIGH INCIDENCE IN PREMATURE INFANTS WITH LOW SERUM BILIRUBIN CONCENTRATIONS

During a 2-year period, 1966 and 1967, 485 low birth weight infants were admitted to the special care unit. Sixteen of these infants expired during the third to sixth days of life, and fourteen of them were examined postmortem. Nine of the fourteen infants (64%) were found to have pathologic evidence of kernicterus characterized by yellow staining of one or more areas of the brain with necrosis of brain cells in the stained areas. None had clinical signs of kernicterus. Peak total serum bilirubin concentrations ranged from 9.4 to 15.6 mg/100 ml in the kernicteric group and from 8.8 to 17.2 mg/100 ml in the group without kernicterus. These infants were of extremely low birth weight and short gestational period, and they had very low Apgar scores and the respiratory distress syndrome. Pathologically the infants demonstrated pulmonary atelectasis, hyaline membranes, and pneumonia as their major findings. Extraneural lesions of hyperbilirubinemia were observed in four infants with kernicterus but not in any of the infants without kernicterus. Neuropathological examination revealed a high frequency of intracranial hemorrhage in the kernicteric group in addition to yellow staining and cell necrosis.