(P-TS-95) Routine DAT for Newborns with ABO Incompatibility is Unnecessary

ABO incompatibility occurs when a mother’s blood type is O and the infant’s blood type is non-O, potentially leading to isoimmune hemolytic disease in newborns, characterized by hyperbilirubinemia and positive direct antiglobulin test (DAT). According to the current guidelines from American Academy of Pediatrics, mature newborns ( >35 weeks) with isoimmune hemolytic disease are at high risk for neurotoxicity, prompting lower bilirubin threshold for initiating phototherapy in these patients. Consequently, some hospitals routinely screen newborns with ABO incompatibility using DAT for risk assessment. This study aims to investigate the necessity of routine DAT in these newborns.

Study

Design/Methods:

We conducted a retrospective analysis of data from mature newborns with ABO incompatibility at a community hospital between October 1, 2022, and March 31, 2024. Variables included maternal age, gravida and Rh status, fetal sex, birth weight, gestational age at birth, ABO type, Rh status, DAT results, and transcutaneous bilirubin (TcB) levels measured 18-24 hours post birth. Phototherapy administration was also noted. Cases with missing data were excluded. Pearson correlation coefficient analysis was used to evaluate variable associations. Multiple logistic regression and area under the receiver operating characteristic curve (AUC) analyses were employed to assess predictive parameters for phototherapy requirement. P< 0.05 was considered statistically significant.

Results/Findings:

Among 339 identified newborns with ABO incompatibility over 18 months, data from 310 (91.4%) were analyzed after exclusions. Correlation analysis revealed associations between TcB and maternal Rh status, fetal ABO blood type, and DAT results (Table 1.), suggesting the infant’s bilirubin level tended to be higher if the mother was Rh positive, the infant belonged to blood group B or had a positive DAT result. Regression analysis evaluating relationships between all study variables and phototherapy requirement identified DAT (Odds ratio=3.71, 95% CI [1.56, 9.44]; p=0.004) and TcB (Odds ratio=2.08, 95% CI [1.69, 2.66]; p< 0.001) as significant predictors. TcB alone yielded an AUC of 0.887 for predicting phototherapy need, which marginally increased to 0.896 when combined with DAT.

Conclusions:

Our findings show that TcB is one single robust predictor of infants’ need for phototherapy in our multivariate model. Incorporating DAT into the model minimally enhances the predictive capacity. The results suggest that monitoring newborns using TcB levels alone to determine need for phototherapy is safe and reliable. Routine DAT screening in newborns is unnecessary; instead, it should be reserved only for those with hyperbilirubinemia to aid in risk stratification, thereby optimizing resource utilization and reducing costs.