Transcutaneous bilirubin (TcB) measurement is a non-invasive method used to assess bilirubin levels in newborns. Bilirubin is a yellow substance produced when red blood cells break down, and elevated levels can lead to jaundice, a common condition in infants. Monitoring these levels is important because very high bilirubin can pose health risks to a newborn’s developing brain. TcB screening helps healthcare providers keep track of bilirubin without needing frequent blood draws.
Understanding Transcutaneous Bilirubin Screening
This method involves a device, called a transcutaneous bilirubinometer, which is gently pressed against the baby’s skin, typically on the forehead or sternum. The device works by directing light into the skin and measuring the intensity of reflected light. This optical technique correlates the light absorbed by bilirubin to its concentration.
This non-invasive approach is preferred for initial assessments of jaundice because it is less stressful for the infant compared to traditional blood tests. It provides quick, almost immediate results, which is beneficial for rapid clinical decision-making. TcB screening is a common practice in hospitals and clinics for universal screening of hyperbilirubinemia.
Interpreting TcB Readings and Normal Ranges
Interpreting TcB readings involves understanding that a “normal range” is not a fixed number but varies significantly based on the infant’s age in hours or days. Newborns naturally experience a transient increase in unconjugated bilirubin during their first few days of life, typically peaking between days 2 and 5. This physiological jaundice is a normal part of their adaptation to life outside the womb.
Healthcare providers use a “bilirubin nomogram” or “jaundice curve” to interpret TcB readings relative to the baby’s precise age in hours. These charts plot bilirubin levels against the infant’s age, dividing them into different risk zones: low, intermediate, and high. A reading in the low-risk zone suggests a very low likelihood of developing severe hyperbilirubinemia, while a reading in the high-risk zone indicates a greater risk.
These nomograms serve as screening guidelines, helping to determine if a baby’s bilirubin level warrants further investigation.
What Elevated Bilirubin Levels Mean
When an infant’s TcB reading falls into a higher-risk zone on the nomogram, it indicates elevated bilirubin levels, a condition known as hyperbilirubinemia. The next step typically involves a confirmatory blood test, specifically a total serum bilirubin (TSB) measurement, to obtain a more precise and accurate reading. TcB measurements correlate well with TSB at lower levels, but their accuracy can be less reliable at very high bilirubin concentrations.
High bilirubin levels are a concern because unconjugated bilirubin can be toxic to brain cells. If left untreated, severe hyperbilirubinemia can lead to a rare but serious complication called kernicterus, which can cause permanent brain damage, including cerebral palsy, hearing loss, and other neurodevelopmental issues.
Common treatment options for elevated bilirubin include phototherapy, which involves exposing the infant to special blue lights. This light helps break down the unconjugated bilirubin in the skin into water-soluble forms that the baby can excrete through urine and stool. In rare cases where phototherapy is insufficient or bilirubin levels are extremely high, an exchange transfusion may be performed, where a portion of the baby’s blood is replaced with donor blood to quickly lower bilirubin levels.
When to Seek Medical Attention
Parents should be aware of visible signs that might indicate worsening jaundice in their newborn. These signs can include the yellowing of the skin spreading from the face to the chest, abdomen, arms, and legs, or becoming more intense in color. Other concerning symptoms include increased lethargy, difficulty waking the baby for feeds, poor feeding, or a high-pitched cry.
It is important to contact a pediatrician immediately if any of these signs are observed, even if a TcB screening has already been performed. While transcutaneous bilirubin screening is a valuable initial tool, clinical judgment remains most important. Healthcare providers will assess the overall clinical picture, considering the baby’s age, risk factors, and the progression of jaundice, to determine the appropriate course of action.