Tcb

TcB stands for transcutaneous bilirubin, a noninvasive method used to estimate bilirubin levels in newborns by measuring skin color with a specialized device. TcB measurements are obtained with a handheld spectrophotometer or bilirubinometer that is placed on the infant’s skin, typically the forehead or sternum. The device emits light and detects reflected wavelengths to infer bilirubin concentration, providing an estimate that is reported in milligrams per deciliter (mg/dL) of total serum bilirubin.

Clinically, TcB serves as a screening tool to identify infants at risk for significant hyperbilirubinemia and to determine whether a blood sample for serum bilirubin measurement is needed. It can also help guide decisions about phototherapy in conjunction with clinical assessment and other risk factors. TcB is valued for being noninvasive and quick, reducing the need for repeated blood draws in many cases.

Accuracy and limitations vary by device and patient factors. TcB readings generally correlate with total serum bilirubin but the relationship is not perfect. Accuracy can be affected by gestational age, hours of life, skin pigmentation, and the presence of bruising, edema, or skin lesions at the measurement site. Recent phototherapy or exchange transfusion, calibration differences between devices, and ambient lighting can also influence results. Consequently, TcB is typically used as a screening estimate, with serum bilirubin measurement pursued when readings are elevated, equivocal, or in high-risk infants.

History and adoption: transcutaneous bilirubin measurement emerged in the late 20th century and has since become a common component of neonatal jaundice management in many clinical settings.