[Severe neonatal anemia due to fetomaternal hemorrhage: an ilustrative case].

Fetomaternal transfusion (FMT) is defined by the transfer of fetal blood into the maternal circulation. The incidence of massive FMT is estimated to be approximately 0.2-0.9 % of births. Although a number of etiologies have been associated with FMT, most causes remain unidentified and the pregnancy is usually asymptomatic. The most frequent symptom is the decrease in fetal movements (26 %) in relation to severe anemia. Several diagnostic modalities for FMT are described (Kleihauer stain, flow cytometry). We describe a case of a newborn with chronic anemia secondary to FMT who, after treatment with transfusions of red blood cells, presented volume overload and clinical worsening as a complication. In this case, our patient needed exchange transfusion for definitive improvement without disability.