Allogeneic hematopoietic stem cell transplantation: transfusion issues

Allogeneic hematopoietic stem cell transplantation (AHSCT) is an intention-to-cure treatment strategy in several malignancies and nonmalignancies. The number of patients receiving AHSCT is increasing due to new indications, and more elderly patients with comorbidities are included in the protocols. Survival of the patients undergoing AHSCT has improved owing to better patient care, including optimization of transfusion support, which has a major contribution. However, transfusion can also be hazardous. Increasing awareness about transfusion and finding the balance between avoiding unnecessary transfusions and transfusing the correct component when needed are the key issues. Myeloablative conditioning results in pancytopenia, and the patients are prone to infections, anemia, and bleeding both before and after transplantation. Until red cell and platelet engraftment, the patients are usually transfusion dependent needing red cell and/or platelet components. Physicians dealing with AHSCT patients should be well informed about the attributes of the blood components they order. Knowledge about transfusion indications, triggers, and how to prevent and manage eventual transfusion complications is also required. The clinical picture can be challenging, and transplantation/treatment-related toxicity/complications can sometimes be difficult to distinguish from a transfusion complication, especially if the latter one took place, for instance, several days or weeks ago. ABO compatibility between the patient and the donor is not a prerequisite when choosing human leukocyte antigen-matched hematopoietic stem cell donor. Consequently, ABO incompatibility exists in ~40% of the cases and brings some immunohematological issues. ABO incompatibility is defined as major, minor, and bidirectional according to the direction of blood group antibodies to blood group antigens in patients and donors. ABO incompatibility necessitates blood components that are compatible with both the patient and the donor.