Kernicterus in premature infants: current prevalence and relationship to NICHD Phototherapy Study exchange criteria.

OBJECTIVE

This study was undertaken to determine the current prevalence of kernicterus in premature neonates and to relate the occurrence of kernicterus to 1) the categorization of the infant as "at risk" by National Institute of Child Health and Human Development (NICHD) Phototherapy Study exchange transfusion criteria, and 2) the clinical management of the infant's hyperbilirubinemia.

DESIGN

Retrospective review of postmortem and clinical records.

SETTING

Magee-Womens Hospital, a University of Pittsburgh Medical Center affiliated hospital with approximately 10,000 deliveries per year and a Level III Neonatal Intensive Care Unit with about 1400 admissions annually.

SUBJECTS

All neonates autopsied between January 1, 1984 and June 30, 1993 who were < 34 weeks gestation and who lived at least 48 hours; a total of 81 infants.

RESULTS

Three infants had kernicterus resulting in a prevalence rate of 4%. These cases included: 1) a 33-week newborn with nonimmune hydrops and a peak bilirubin of 26 mg/dl; 2) a 25-week newborn with asphyxia, hyaline membrane disease, grade IV intraventricular hemorrhage, necrotizing enterocolitis, meconium peritonitis, sepsis, prolonged acidosis, and a peak bilirubin of 11.3 mg/dl; and 3) a 24-week newborn with asphyxia, hyaline membrane disease, grade III intraventricular hemorrhage, and a peak serum bilirubin of 18.5 mg/dl. Of the remaining 78 infants who did not have kernicterus, peak bilirubin ranged from 3.6 to 22.5 mg/dl and 56% had bilirubin levels greater than that suggested as a criterion for exchange transfusion by NICHD Phototherapy Study guidelines; yet all but three were managed with phototherapy alone.

CONCLUSIONS

We conclude that kernicterus is currently an uncommon event in preterm infants, even when bilirubin levels are allowed to rise above those previously thought to place the premature infant at risk.