Validity of Cord Bilirubin and Hemoglobin in Predicting the Need for Phototherapy Among Neonates with ABO or Rh Incompatibility: A Diagnostic Test Evaluation

Background Though umbilical cord bilirubin and hemoglobin cutoff values recommending exchange transfusion are available for neonates with ABO or Rh incompatibility, those for phototherapy are not. Objective To determine the predictive accuracy of cord bilirubin and hemoglobin for hyperbilirubinemia requiring phototherapy within the first 5 days of life among neonates with ABO and Rh incompatibility. Methodology Study Design A prospective observational study was conducted from January 2022 to December 2022. Study Participants Neonates with Rh or ABO incompatibility Intervention The study participants were observed for hyperbilirubinemia requiring phototherapy within the first 5 days. Outcome The receiver operating characteristic (ROC) curve was plotted to determine the cutoff value of cord bilirubin and hemoglobin for predicting the need for phototherapy. Results Out of the 416 analyzed, 53.8% ( n = 224) of the babies required phototherapy. ROC curve analysis showed umbilical cord bilirubin as a moderate predictor in determining the need for phototherapy, with an area under the curve (AUC) of 0.74 (95% CI: 0.69-0.79). The cutoff value of >2.25 mg/dL for cord bilirubin had a sensitivity of 75% and a specificity of 60%. A cord bilirubin value of 1.95 mg/dL had 90% sensitivity, and a value of 3.25 mg/dL had 100% specificity in predicting the need for phototherapy. Cord hemoglobin was not a good predictor for determining the need for phototherapy. Conclusion Though cord hemoglobin is a poor predictor in determining the development of significant hyperbilirubinemia requiring phototherapy in neonates with ABO and Rh setup, a cord bilirubin value above 2.25 mg/dL can be used as a cutoff for the same.