Direct antiglobulin test in the differential diagnosis of ABO hemolytic disease of the newborn: an important tool with high negative predictive value

Background: Hemolysis due to ABO incompatibility is an important differential diagnosis in newborns presenting with jaundice. Clinical studies evaluating ABO hemolytic disease of fetus and newborn (ABO-HDFN) question the diagnostic value of the direct antiglobulin test (DAT) in this situation. Goals: To determine the clinical and laboratorial findings associated with the occurrence of ABO-HDFN and to evaluate the accuracy of DAT as a diagnostic tool. Methods: This was a nested case control study with a cohort of 4122 newborns. Clinical and immunohematological data were retrieved from medical files including clinical and laboratorial factors associated with ABO-HDFN. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of positive DAT were calculated. Results: Among the 4122 newborns, 44 had the diagnosis of ABO-HDFN. Positive DAT, group O mother and group A newborn were significantly associated with the occurrence of neonatal jaundice and this association persisted in a multivariable model (p-value <0.001). DAT presented 65.85 % sensitivity, 96.28 % specificity, 16.9 % PPV and 99.6 % NPV for the diagnosis of ABO-HDFN. There were no cases of positive DAT in cases other than O/A and O/B incompatibilities. The newborn hemoglobin was significantly lower in O/A incompatibility (p-value <0.001). Conclusion: Positive DAT, mother of group O and newborn of group A are independent risk factors associated with ABO-HDFN. DAT exhibited high NPV for the diagnosis of this complication. Thus, performing DAT in newborns with O/A and O/B incompatibilities is a costeffective strategy that can be applied as routine by blood banks. (c) 2024 Published by Elsevier Espana, S.L.U. on behalf of Associacao Brasileira de Hematologia, Hemoterapia e Terapia Celular. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).