Purpose of Postpartum Newborn Laboratory Tests
The collection of laboratory tests in the postpartum newborn period is essential for early detection of potentially serious conditions that could impact morbidity, mortality, and quality of life.
Blood Glucose
- Blood glucose testing identifies hypoglycemia which can cause neurological damage if left untreated, especially in infants with risk factors such as maternal diabetes, prematurity, or low birth weight 1.
ABO and Rh Blood Type
- Blood typing determines the infant's blood group and Rh status to identify potential incompatibilities with maternal blood type that could lead to hemolytic disease of the newborn 1.
Direct Antibody Titer (DAT/Direct Coombs)
- DAT detects antibody-coated red blood cells in the infant's circulation, indicating maternal-fetal blood group incompatibility that may lead to hemolytic disease and hyperbilirubinemia 1, 2.
Transcutaneous Bilirubin
- Transcutaneous bilirubin provides a non-invasive screening method to detect jaundice and estimate serum bilirubin levels, helping to identify infants at risk for hyperbilirubinemia without blood sampling 1, 3.
Serum Bilirubin
- Serum bilirubin measures the actual concentration of bilirubin in the blood to diagnose hyperbilirubinemia and determine the need for phototherapy or exchange transfusion to prevent kernicterus 1, 4.
Hearing Screen
- Hearing screening identifies congenital hearing loss early, allowing for prompt intervention to prevent delays in speech, language development, and learning that could affect quality of life 1.
CHD (Congenital Heart Disease) Screening
- CHD screening through pulse oximetry detects critical congenital heart defects that might otherwise go undetected at birth, allowing for timely intervention to prevent sudden cardiac decompensation and death 1.
Blood Spot (Newborn Screening)
- Blood spot testing screens for numerous metabolic, endocrine, and genetic disorders that, if identified early, can be treated to prevent intellectual disability, physical disability, or death 1.
Important Considerations
- Timing of collection is critical; some tests (like metabolic screening) may need to be repeated if performed before 24 hours of milk feeding 1.
- Results of these screenings should be reviewed before discharge and appropriate follow-up arranged for abnormal findings 1.
- False positives can occur, particularly with transcutaneous bilirubin measurements in certain populations, requiring confirmation with serum testing when indicated 3, 5.
- Early identification through these screenings allows for timely intervention, significantly improving outcomes and quality of life for affected infants 1.