Maternal ABO Discrepancy Caused by Massive Fetomaternal Hemorrhage: a Case Report

Background: Fetomaternal hemorrhage (FMH) can lead to severe, life-threatening fetal anemia depending on the amount of blood loss. FMH may be underdiagnosed as it is not routinely tested. In our report, we present a rare case of obvious mixed-field agglutination of maternal ABO forward typing caused by massive fetomaternal hemorrhage. Methods: We retrospectively evaluated the clinical information of a 42-year-old pregnant woman who was admitted to our hospital at gestational week (GW) 36(_5/7) due to fetal distress. She later delivered a male infant with severe anemia by cesarean section. Results: This case had an unusual maternal hemoglobin elevation before delivery and the maternal blood type identification showed ABO discrepancy. After other causes were excluded, FMH was suspected. The Kleihauer-Betke (K-B) test was done on the mother's blood, indicating a massive FMH. Conclusions: Massive FMH may be a cause of ABO discrepancy of pregnant woman. FMH should be considered when we get a result of a mixed-field agglutination of pregnant woman with other possible causes excluded.