Clinical value of the direct antiglobulin test for the identification and estimation of severity of hemolytic disease of fetus and newborn

Hemolytic disease of fetus and newborn (HDFN) is still important because of its high mortality and long-term morbidity although its incidence has been decreasing in recent years. Aim: In this study, we aimed to determine the incidence of ABO and non-ABO HDN (Hemolytic disease of newborn) and to investigate the value of Direct Antiglobulin Test (DAT) positivity in detecting FHM (Hemolytic disease of fetus). Since prenatal treatment options are available, immunohematological tests and algorithms have been developed to identify HDFN during pregnancy. We aimed to review the algorithms that have been developed to prevent alloimmunization and to ensure proper management if developed. We purposed to investigate the use of immunohematological laboratory tests in detection and management of perinatal HDFN. Materials and Methods: 1737 newborns who were born in Ege University Medical School Hospital between January 1, 2018 and December 31, 2018 and whose blood samples were sent to our blood center to study DAT and their mothers are included. ABO, Rh blood group, DAT result, hospitalization, phototherapy requirement, bilirubin and hematocrit levels, intrauterine disease status, presence of IUGR, antibody screening and antibody identification studies of were recorded to detect the presence of perinatal HDFN. Gestational week, gravida, Rh and ABO blood group, indirect antiglobulin (IAT), antibody screening results, IAT titration and antibody identification performed if needed of the pregnant women are recorded. The relationship between HDFN and anti-D immunoglobulin administered to Rh D negative mothers was examined. This information was obtained from Department of Obstetrics and Gynecology hospitalization files, hospitalization epicrisis of the Newborn Department and birth registry files. The rate of phototherapy (9.4%) in DAT positive cases was significantly higher than in DAT negative cases (1.8%). No newborn phototherapy with DAT <2 was positive. In contrast, 8 of 9 patients with DAT ≥2 + who received phototherapy were newborns with ABO incompatibility. Only 20 out of 116 newborns with Rh D incompatibility had weak DAT positivity (<2+) and none required phototherapy. Results: 95(5.4%) of 1737 newborns in this study was detected DAT positive and phototherapy receiving rates, duration of phototherapy, mean maximum bilirubin and IUGR presence in this group was statistically significantly higher. While the rate of receiving phototherapy was statistically significant in the ABO incompatibility group (p = 0.018), there was no statistically significant difference in the rate of receiving phototherapy in newborns with Rh D incompatibility. Antibody screening was performed in 820 (47.2%) of the pregnant women and 50 of them were positive. Antibodies were identified in 43 (86%) of these pregnant women with positive antibody screening. Antibodies against D (69%) were the most common, followed by the presence of antibodies against Kell 11%. Rh D immunoglobulin, which is the most effective way to prevent HDFN, was performed to 104 (60.5%) of 172 pregnant women and not in 52 of 68 pregnant women because newborn was Rh D negative. Only one of the 95 DAT positive patients had antibody screening. A total of 31 newborns underwent antibody screening and none of them received phototherapy. Conclusion: Weak (<+2) DAT positivity was not found to have a clinical significance associated with hemolysis in our case group. The possibility of clinical hemolysis to be associated with significant DAT ≥+2 positivity was also not strong. In neonates, DAT positivity and DAT negative infants who needed phototherapy were not examined for immune hemolysis. On the other hand, maternal follow-up was adequate and appropriate for monitoring and management of allo-immunization development.