What are the potential side effects of platelet transfusions?

Side Effects of Platelet Transfusion

Platelet transfusions carry well-documented risks including febrile and allergic reactions, bacterial contamination, transfusion-related acute lung injury (TRALI), transfusion-associated circulatory overload (TACO), viral transmission, alloimmunization, and circulatory congestion. 1

Immediate Life-Threatening Complications

Transfusion-Related Acute Lung Injury (TRALI)

• TRALI is a leading cause of transfusion-related mortality and presents as acute lung injury within 6 hours of transfusion with hypoxemia, respiratory distress, dyspnea, bilateral pulmonary infiltrates, and fever 2, 3
• Fresh frozen plasma (FFP) and platelet concentrates are the blood products most frequently implicated in TRALI 2, 3
• The mechanism involves donor leukocyte antibodies (HLA class I, class II, or granulocyte-specific) interacting with recipient neutrophils 3
• Stop the transfusion immediately when TRALI is suspected and provide critical care respiratory support—do NOT give diuretics as they are ineffective and may worsen the condition 2, 3
• Blood banks now screen donors for leukocyte antibodies and preferentially use male-only plasma donors to reduce TRALI risk 3

Transfusion-Associated Circulatory Overload (TACO)

• TACO is now the most common cause of transfusion-related mortality, occurring during or up to 12 hours after transfusion 3
• Presents with acute respiratory compromise, pulmonary edema, cardiovascular changes (hypertension, tachycardia), and evidence of fluid overload 3
• Patients at highest risk include those over 70 years old, non-bleeding patients, and those with heart failure, renal failure, or hypoalbuminemia 3
• Treatment requires immediate cessation of transfusion and diuretic therapy (in contrast to TRALI) 3

Bacterial Contamination

• Bacterial contamination should be suspected if patients experience severe febrile reactions during or shortly after platelet transfusions 1
• Storage at 20°C to 24°C creates conditions that permit bacterial growth, making platelets the blood product with highest contamination risk 1
• Storage time is limited to 5 days (or 7 days with bacterial detection testing or pathogen reduction technologies) to minimize this risk 1, 4
• Stop the transfusion immediately, obtain blood cultures from both patient and blood product, and strongly consider empiric antibiotics, particularly in neutropenic recipients 1, 4

Common Adverse Reactions

Febrile and Allergic Reactions

• Febrile or allergic transfusion reactions are among the most common side effects of platelet transfusion 1
• Stored platelet supernatants contain inflammatory mediators including IL-6, IL-27, sCD40L, and OX40L that are closely linked to febrile reactions 5
• These reactions result from the complex changes that occur during platelet storage, including partial activation, up-regulation of inflammatory mediators, and micro-particle formation 6

Alloimmunization and Platelet Refractoriness

• Repeated platelet transfusions induce alloantibodies in recipients, potentially resulting in platelet transfusion refractoriness (PTR) 7, 8
• The incidence of alloantibody-mediated refractoriness can be decreased in patients with acute myeloid leukemia when both platelet and RBC products are leukoreduced before transfusion 1
• Prestorage leukoreduction is recommended from the time of diagnosis to ameliorate this problem 1
• Leukoreduction also substantially reduces transfusion reactions and transmission of cytomegalovirus (CMV) infection 1

Additional Serious Complications

Transfusion-Associated Graft-Versus-Host Disease

• This is a rare but usually fatal complication resulting from transfusion of viable lymphocytes capable of immune attack against the recipient 1
• Prevention requires pretransfusion gamma irradiation of blood products for high-risk patients including stem-cell transplant recipients, those receiving blood from partially matched family members, and patients with severe immunosuppression (e.g., Hodgkin's lymphoma) 1
• Leukocyte depletion alone does not eliminate this risk 1

Hemolytic Reactions

• Rare hemolytic reactions can occur due to incompatible plasma, particularly when O donor platelets are transfused to A or B recipients 1
• Anti-A and anti-B antibodies can bind to incompatible platelets and soluble antigens, potentially impairing hemostasis and increasing bleeding 5
• ABO-compatible products should be provided whenever possible, though clinically significant hemolysis is unusual in adult recipients 1

Viral Transmission

• All platelet products are tested for required transfusion-transmitted diseases 1
• Pathogen reduction technologies using UV irradiation with photosensitizers are now available and approved to further decrease infection transmission risk 1

Emerging Concerns

Pro-Inflammatory and Immunomodulatory Effects

• Platelet transfusions are pro-inflammatory and may be pro-thrombotic 5
• Stored platelet supernatants contain biological mediators such as VEGF and TGF-β1 that may compromise the host versus tumor response, particularly concerning in patients receiving many transfusions for acute leukemia 5
• Evidence suggests that removing stored supernatant may improve clinical outcomes 5
• Platelet-derived lipids are implicated in transfusion-related acute lung injury 5

Clinical Outcomes

• Controversial outcome data suggest that in some populations, platelet transfusions are associated with worse patient outcomes 6
• These associations may result from biologic changes during storage, lack of HLA matching, or overuse of platelet products 6

Risk Mitigation Strategies

To minimize adverse effects, clinicians should: 1, 3

• Use leukoreduced blood products universally
• Provide ABO-compatible platelets when possible
• Irradiate products for immunocompromised patients
• Transfuse single units in non-hemorrhaging patients and reassess before additional units
• Monitor vital signs closely during and after transfusion
• Report all suspected transfusion reactions immediately to the blood bank
• Consider pathogen-reduced platelet products when available