RT Book, Section A1 Gomella, Tricia Lacy A1 Cunningham, M. Douglas A1 Eyal, Fabien G. A1 Tuttle, Deborah J. SR Print(0) ID 1107528079 T1 ABO Incompatibility T2 Neonatology: Management, Procedures, On-Call Problems, Diseases, and Drugs, 7e YR 2013 FD 2013 PB McGraw-Hill Education PP New York, NY SN 9780071768016 LK accesspediatrics.mhmedical.com/content.aspx?aid=1107528079 RD 2024/03/29 AB Isoimmune hemolytic anemia may result when ABO incompatibility occurs between the mother and the newborn infant. This disorder is most common with blood type A or B infants born to type O mothers. The hemolytic process begins in utero and is the result of active placental transport of maternal isoantibody. In type O mothers, isoantibody is predominantly 7S-IgG (immunoglobulin G) and is capable of crossing the placental membranes. Because of its larger size, the mostly 19S-IgM (immunoglobulin M) isoantibody found in type A or type B mothers cannot cross. Symptomatic clinical disease, which usually does not present until after birth, is a compensated mild hemolytic anemia with reticulocytosis, microspherocytosis, and early-onset unconjugated hyperbilirubinemia.