موضوع: ABO Hemolytic disease of the newborn الإثنين يوليو 18, 2016 6:21 pm
ABO Hemolytic disease of the newborn: ================================ Anti-A and anti-B antibodies are usually IgM and do not pass through the placenta, but some mothers "naturally" have IgG anti-A or IgG anti-B antibodies, which can pass through the placenta. Exposure to A-antigens and B-antigens, which are both widespread in nature, usually leads to the production of IgM anti-A and IgM anti-B antibodies but occasionally IgG antibodies are produced. Diagnosis is usually made by investigation of a newborn baby who has developed jaundice during the first week of life. ABO HDN is generally mild and short-lived and only occasionally severe because: 1-IgG anti-A (or IgG anti-B) antibodies that enter the fetal circulation from the mother find A (or B) antigens on many different fetal cell types, leaving fewer antibodies available for binding onto fetal red blood cells. 2-Fetal RBC surface A and B antigens are not fully developed during gestation and so there are a smaller number of antigenic sites on fetal RBCs. The antibodies in ABO HDN cause anemia due to destruction of fetal red blood cells and jaundice due to the rise in blood levels of bilirubin a by-product of hemoglobin break down. If the anemia is severe, it can be treated with a blood transfusion, however this is rarely needed. On the other hand, neonates have underdeveloped livers that are unable to process large amounts of bilirubin and a poorly developed blood-brain barrier that is unable to block bilirubin from entering the brain.This can result in kernicterus if left unchecked. If the bilirubin level is sufficiently high as to cause worry, it can be lowered via phototherapy in the first instance or an exchange transfusion if severely elevated.