[Transfusion in sickle cell anemia].

Although blood transfusion (BT) therapy remains a key component of the weaponry used to treat acute and chronic sickle cell disease complications, its indications and modalities are currently the focus of a critical reappraisal prompted by the introduction of hydroxyurea, recent improvements in allogeneic bone marrow transplantation, and increasing attention to safety concerns. Expected benefits of each BT should be carefully weighed against the risks of infections, immunologic complications, and iron overload. Simple or exchange BT can be used. In emergency situations, the only effective means of improving tissue oxygenation and limiting blood vessel occlusion is dilution or removal of HbS by simple or exchange BT, respectively; simple BT is indicated in severe anemia or acute hypovolemia and exchange BT in acute vasoocclusive crisis or acute infection. In nonemergency situations, long-term exchange BT programs geared to maintain the HbS level around 30% are used to stabilize existing lesions and to prevent recurrences; they have been proved effective in preventing recurrent stroke in patients who are not candidates for allogeneic bone marrow transplantation. Situations in which BT therapy is widely used despite controversy regarding its value and modalities include the prevention of complications of pregnancy, the prevention of perioperative complications, and the prevention of recurrences of severe vaso occlusive crisis in patients eligible for hydroxyurea therapy. Advances have been made in the minimization of BT-related complications (alloimmunization, viral infections, iron overload) through critical appraisal of the need for each BT, careful selection of the most appropriate blood product, and a change in BT technique resulting in a reduction in the number of blood donors.