(Posted:28-Jul-2015)

Isoimmunization is defined as a production of immune antibodies in an individual in response to an antigen derived from another individual of the same species provided,the first one lack the antigen. Isoimmunization may occur by two mechanism: *Following incompatible blood transfusion. *Following fetomaternal heamorrhage between a mother &a incompatible foetus. Predispositions to fetomaternal haemorrhage: *Spontaneous or induced abortion. *Amniocentesis. *Chorionic villus sampling. *Placenta previa. *Abruptio placenta. *Featal death *Cesarean section. Affects of Rh negative pregnancy: Fetus & neonate: Hydrops fetalis, Icterus gravis neonatorum, Congenital anaemia of newborn. Mother: Preeclamsia, Polyhydramnios, Big size of the baby with hazard, Postpartum haemorrhage. Heamolytic disease of the newborn occurs when maternal antibody cross the placenta &destroy; Rh positive fetal blood cells->fetal anaemia->extramedullary erythropoesis->immature erythrocyt are present in fetal blood.When fetal RBC destruction far exceeds production & causes severe anaemia,erythroblastosis fetalis occur. Prevention of Rh-isoimmunization: 1)To prevent active immunization: Rh anti-D immunoglobulin(IgG) is administered intramuscularly to mother. 2)To prevent or minimize feto-maternal bleed: •Precautions during caeserean section •Amniocentesis should be done after sonographic localization of the placenta to prevent its injury. 3)To prevent mismatched blood transfusion. Investigation protocol: ( 1)At first antenatal visit- Blood for grouping & Rh typing routine for all pregnant women. (2)If women is Rh negative,Rh grouping of husband . (3)Antibody detection by indirect coombs test. (4)Ultrasonography. (5)Amniocentesis. (6)Chorionic villus sampling.