Management of pregnancy sensitized with anti-Inb with monocyte monolayer assay and maternal blood donation.

CONCLUSIONS: Maternal red blood cell (RBC) alloantibodies can cause hemolytic disease of the fetus and newborn (HDFN). Although much is described about common antibodies associated with HDFN, management of a pregnancy complicated by a maternal rare antibody presents several challenges related to assessment of fetal anemia risk, availability of blood for transfusion to the mother and/or the fetus or newborn if needed, and planning for delivery in the case of maternal hemorrhage. Here we report the laboratory medicine workup of a patient who presented for obstetrical care in the United States in the third trimester and had a rare antibody (anti-Inb). Prenatal antibody detection testing demonstrated maternal anti-Inb in a 28-year-old woman (gravida 4 para 1021). Ultrasound could not rule out fetal anemia. Monocyte monolayer assay was performed to assess for the clinical significance of the anti-Inb and revealed that the antibody may be capable of causing accelerated clearance of antigen-positive RBCs. A local and national query revealed that no appropriate units of RBCs were available for either the mother or neonate. Given this information, serial maternal autologous blood donations were performed, and a comprehensive care plan with a multidisciplinary approach for delivery, neonatal management, and preparation for hemorrhage was developed. Published data and our experience suggest that maternal blood donation appears to be a safe and effective way to manage mothers who cannot safely use the community blood supply. Involvement of obstetric, transfusion medicine, anesthesia, and neonatology providers was imperative for a favorable outcome. The antibody did not cause clinically significant anemia in this infant.