Direct bilirubin measurements in jaundiced term newborns. A reevaluation.

To investigate the usefulness of measuring direct bilirubin in jaundiced term newborns, we reviewed the outcome of 5255 such measurements on 2877 term (37 weeks' gestation) newborns in two hospitals. Direct bilirubin tests were ordered 15 times as often per infant at the University of California, San Francisco, as at Stanford (Calif) University, and the reported results were more than twice as high. In most of the 149 infants with high (greater than 95th percentile) direct bilirubin levels, the high levels remained unexplained (52% of cases) or were due to apparent laboratory errors (21% of cases). Forty infants (27%) had conditions sometimes associated with high direct bilirubin levels. Elevation of direct bilirubin levels contributed to the diagnosis in only four of these infants. All had minor laboratory abnormalities that resolved spontaneously. Because of their low yield and poor specificity, direct bilirubin tests are seldom helpful in evaluating jaundice in term newborns.