Elevated umbilical cord bilirubin levels may be an early predictor of hemolytic disease of the fetus and newborn (HDFN), according to findings recently published in the European Journal of Cardiovascular Medicine.
Hyperbilirubinemia, or high bilirubin levels, is one of the primary signs of HDFN. Cord bilirubin testing offers an advantage over blood testing, as it is non-invasive and allows for earlier diagnosis. “Neonates can benefit from prompt interventions, avoiding complications like severe anemia or neurological damage,” the authors wrote.
The study included 158 neonates positive for the Rh antigen who were born to mothers negative for the Rh antigen between June 2022 and June 2024. All participants were required to be singleton births born at full gestation. Patients with congenital or chromosomal anomalies, severe asphyxia at birth, and a history of blood transfusion during pregnancy were ineligible for participation. An additional 119 infants were included as controls.
The investigators established 1.9 mg/dl bilirubin as the cutoff value for high cord bilirubin levels. This value had a specificity of 97.8%, meaning 97.8% of those who truly did not have hemolysis were classified correctly. The positive predictive value of the test was 95.74%, meaning that 95.74% of those who tested positive truly had hemolysis.
Read more about HDFN testing and diagnosis
The study found that children of mothers who had been pregnant previously were more likely to have high bilirubin levels compared to children of mothers experiencing their first pregnancy. This may be attributed to prior transfer of fetal blood into the maternal bloodstream, which raises the risk of alloimmunization, they explained.
Additionally, they found that neonates with high cord bilirubin levels were more likely to require phototherapy (P < 0.05) and exchange transfusion (P < 0.05).
“Cord sampling proves to be an essential predictive marker of the risk of hemolysis in the neonate earlier to allow for early initiation of therapeutic measures and reducing the risk of rapid hemolysis and further, long term complications such as bilirubin encephalopathy, emerging as a cornerstone of non invasive care,” the team concluded.
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