Role of COHb Level in Newborns with ABO Blood Group Incompatibility in Predicting Newborn Jaundice Risk

Objective: Neonates with hyperbilirubinemia are at risk of brain damage, and at least two-thirds of neonates show clinical signs of jaundice in the first week of life. To predict the correlation between cord carboxyhemoglobin (COHb) with postnatal 24th-hour total serum bilirubin (TSB) level in newborns with ABO incompatibility. Methods: This retrospective cohort study included newborns older than 35 weeks of gestation who were followed up in the Neonatal Intensive Care Unit of Tokat Gaziosmanpaşa University Hospital between January 2019 and December 2023. Patients were divided into three groups; Group 1: ABO incompatibility with direct Coombs (DC) positive newborns, Group 2: ABO incompatibility and DC negative newborns, and Group 3: ABO incompatibility with no known hemolysis risk factors. Results: A total of 292 patients in 3 groups were included in the study. Group 1 consisted of 93 patients, Group 2 consisted of 99, and Group 3 consisted of 100. The mean newborn cord COHb was 1.59±0.56%, the mean cord bilirubin was 3.12±2.05 mg/dL, the mean 24-h TSB was 6.40±1.99 mg/dL, and the mean cord blood gas hemoglobin was 18.06±2.57 g/dL. In the first group, the correlation between cord COHb and 24-h TSB was high and statistically significant. In the second group, the correlation between cord COHb and 24-h PTH was low and statistically significant. Conclusion: The use of COHb as a predictor of 24-h postnatal TSB levels in ABO-incompatible neonates is plausible.