Transcutaneous bilirubin measurements in full-term infants.

A total of 292 transcutaneous bilirubin (TcB) measurements were performed in 157 white full-term infants: 157 were obtained from the forehead and 135 from the midsternum. TcB measurements correlated well with serum bilirubin determinations (r = .93, P less than .0001). The sensitivity of the test was 100% and the specificity 97%. It was possible to establish guidelines for the TcB measurement which identified all infants whose serum bilirubin concentrations exceeded 12.9 mg/100 ml (221 mumoles/liter) with no false-negative and only five false-positive determinations (3%). The positive predictive value for the TcB measurements was 58%. This implies that, in our population, an infant with a TcB index greater than or equal to 24 has a 58% chance of having a serum bilirubin concentration greater than 12.9 mg/100 ml. The negative predictive value was 100%. Thus, a negative test will correctly predict the absence of hyperbilirubinemia in all cases. As these measurements were obtained prospectively in a well-baby population with a prevalence of hyperbilirubinemia (greater than 12.9 mg/100 ml) of 4.5%, the positive predictive value should be applicable to other similar populations and will, in fact, increase in populations with a higher prevalence of hyperbilirubinemia. TcB measurements can be recommended for the identification of significant neonatal jaundice in full-term infants. It is important to recognize, however, that because of potential variations in TcB meters as well as serum bilirubin measurements in different laboratories, each institution should establish its own criteria for the use of this instrument.