From the Guidelines
Blood transfusion is recommended for patients with sickle cell disease during acute complications or as preventive therapy in specific situations, as outlined in the American Society of Hematology 2020 guidelines for sickle cell disease: transfusion support 1.
Indications for Transfusion
The following situations are indications for blood transfusion in patients with sickle cell disease:
- Severe acute chest syndrome (when oxygen saturation falls below 90% despite supplemental oxygen)
- Stroke
- Multi-organ failure
- Severe symptomatic anemia (typically when hemoglobin drops below 5-6 g/dL or falls more than 2 g/dL below baseline)
Preventive Therapy
Preoperative transfusions are recommended before major surgeries to bring hemoglobin levels to approximately 10 g/dL to reduce surgical complications, as suggested by the guideline on the peri-operative management of patients with sickle cell disease 1. Chronic transfusion therapy is used preventively for children with abnormal transcranial Doppler ultrasound results to reduce stroke risk, typically maintaining hemoglobin S levels below 30%, as recommended by the American Heart Association 1. Patients with a history of stroke may require indefinite transfusion therapy.
Goal of Transfusion
The goal of transfusion is to increase oxygen-carrying capacity by providing normal red blood cells while diluting the sickled cells, thereby improving tissue oxygenation and reducing vaso-occlusive complications.
Important Considerations
Extended phenotype matching is important to reduce the risk of alloimmunization, and iron chelation therapy may be necessary for patients receiving chronic transfusions to prevent iron overload, as noted in the American Society of Hematology 2020 guidelines for sickle cell disease: transfusion support 1. Donor red cells should be HbS negative and must be compatible for ABO, Rh and Kell antigens and for additional known allo-antibodies, as advised by the guideline on the peri-operative management of patients with sickle cell disease 1.
From the Research
Indications for Blood Transfusion in Sickle Cell Disease
- Blood transfusion is an essential treatment for many patients with sickle cell disease (SCD) 2, 3, 4, 5, 6
- The primary goal of transfusion is to increase blood oxygen carrying capacity and decrease the relative amount of HbS to HbA to mitigate vaso-occlusion in small blood vessels 2
- Transfusion may be utilized in efforts to intervene in the evolution of potentially life-threatening complications of SCD such as:
- Transfusion is also useful in several non-acute settings, such as:
Types of Blood Transfusion
- Simple transfusion may be utilized in situations where correction of severe anemia and reduction in HbS may be achieved without removal of RBCs 2
- Partial manual RBC exchange, which removes blood containing HbS by phlebotomy and replaces with donor blood transfusion sequentially, allows for larger changes in the ratio of HbS to HbA when compared to simple transfusion 2
- Automated RBC exchange by apheresis is useful in situations where a rapid and drastic HbS reduction is indicated 2, 3
- Exchange blood transfusion is used in some complications of the disease such as ACS, priapism, or peri-operatively 4, 5
Considerations for Blood Transfusion
- Vascular access is an important consideration for transfusion, with central venous catheters and implantable venous access devices may be necessary for adequate access over time 2
- Blood bank considerations include adequate RBC antigen matching to mitigate the risk of RBC alloimmunization, of which patients with SCD are at risk of developing 2, 3, 6
- Transfusion carries risks for infectious disease transmission, as well as immunologic and inflammatory sequelae, and iron overload occurs frequently in patients with SCD who may be chronically transfused 3, 6