An unusual case of ABO-haemolytic disease of the newborn.

Haemolytic disease of the newborn (HDN) is a clinical condition in which foetal red blood cells are destroyed by maternal alloantibodies directed against red cells antigens acquired from the father. These antibodies usually belong to the Rhesus (Rh) or ABO blood group systems. ABO-HDN is usually a sub-clinical condition and less severe than Rh-HDN. The placenta is relatively impermeable to naturally occurring IgM anti-A/anti-B antibodies. However, immune anti-A and anti-B of the IgG type will cross the placenta and may thus cause ABO-HDN. ABO-HDN is the commonest in Group O mothers having A infants. Occasionally it is seen in Group O or A (A2) mothers of Group B infants. The most severe disease is seen in immune anti-B rather than anti-A antibodies. There are at present no satisfactory methods to predict ABO-HDN in the antepartum period. We report here a case of ABO-HDN where mother who was B, Rh-positive; delivered a baby girl of A1B, Rh-positive who developed severe haemolytic disease. The baby was the third child. To our knowledge this is the first of this kind of severe ABO-HDN in Bangladesh and one of the rarest ABO-HDN cases in the world.