New approaches in the treatment of haemolytic disease of the fetus.

The incidence of Rh haemolytic disease of the fetus and newborn complicating pregnancy has fallen since the implementation of prophylaxis with Rh immune globulin. However, occasional mismatched blood transfusions and ineffective or inadequate prophylaxis still result in a few Rh-alloimmunized patients requiring treatment during pregnancy. The development of a safe technique for obtaining pure fetal blood samples has provided the opportunity to assess correctly the severity of anaemia and to study fetal haematology and biochemical parameters, and hence to gain a better understanding of the pathophysiology of this condition. The aim of antenatal management is to predict whether or not the fetus is severely affected, to correct fetal anaemia and to deliver the baby at the optimal time. Fetal IVT is the standard treatment in severe Rh alloimmunization in many centres. However, high volume transfusion without overloading the fetal circulation, as well as increasing the interval between transfusions without jeopardizing the fetal condition, can be achieved by a combination of IVT and IPT. Thus, the total number of transfusions needed and the overall procedure-related risk for each fetus is reduced. With the recent advances in fetal medicine, haematology and neonatology, the survival rate of affected fetuses in some centres is now about 90%. Fetal death will continue to be associated with two sets of circumstances: trauma or complications due to IVT or IPT in early gestation when delivery is not feasible, and late referrals with such severe hydrops that its reversal is not possible. There is still, therefore, a need for research into new methods of treatment, such as high dose intravenous IgG, which can non-invasively diminish fetal red cell destruction.