Transcutaneous bilirubin measurement: does it work in the real world?

In their study of the routine use of transcutaneous bilirubin (TcB) measurements in 27 well infant nurseries, Taylor et al found that 2.2% of TcB measurements underestimated the clinical laboratory measurement of total serum bilirubin (TSB) by $3.0 mg/dL, and the tendency for TcB to underestimate TSB increased with advancing newborn age (presumably up to the length of stay of a normal newborn). They nevertheless conclude that TcB measurements “provide reasonably accurate estimates of TSB values” and work well enough as a method for identifying significant hyperbilirubinemia.