a woman has antibodies, she is at high risk for a future transfusion reaction if she is in need of a blood transfusion. For this reason, she is advised to carry a medical alert card at all times and inform all doctors and emergency personnel of her antibody status. The absence of antibodies however does not preclude a woman from having a transfusion reaction: "Acute hemolytic transfusion reactions may be either immune-mediated or nonimmune-mediated. Immune-mediated hemolytic transfusion reactions caused by immunoglobulin M (IgM) anti-A, anti-B, or anti-A, B typically result in severe, potentially fatal complement-mediated intravascular hemolysis. Immune-mediated hemolytic reactions caused by IgG, Rh, Kell, Duffy, or other non-ABO antibodies typically result in extravascular sequestration, shortened survival of transfused red cells, and relatively mild clinical reactions. Acute hemolytic transfusion reactions due to immune hemolysis may occur in patients who have no antibodies detectable by routine laboratory procedures." For a summary of transfusion reactions in the US, see reference. Epidemiology In 2003, the incidence of Rh(D) sensitization in the United States was 6.8 per 1000 live births; 0.27% of women with an Rh incompatible fetus experience alloimmunization. Other animals Hemolytic disease of the newborn is most commonly seen in kittens (where it is known as "fading kitten syndrome") and foals. It has also been reported in puppies. See also Exchange transfusion Rh disease Alloimmunization Hemolytic disease of the newborn (anti-Kell) Hemolytic disease of the newborn (anti-Rhc) Hemolytic disease of the newborn (anti-RhE) Hemolytic disease of the newborn (ABO) Neonatal red cell transfusion References Further reading External links Haemorrhagic and haematological disorders of fetus and newborn Disorders originating in the perinatal period Infant mortality Transfusion medicine Acquired hemolytic anemia