What are the indications for transfusing platelets (platelet transfusion) in patients with thrombocytopenia (low platelet count)?

Indications for Platelet Transfusion in Thrombocytopenia

Platelet transfusions should be administered prophylactically in hospitalized adult patients with therapy-induced hypoproliferative thrombocytopenia when the platelet count is ≤10 × 10^9 cells/L, with a single apheresis unit or equivalent being sufficient to reduce the risk of spontaneous bleeding. 1, 2

Prophylactic Platelet Transfusion Thresholds

Therapy-Induced Hypoproliferative Thrombocytopenia

• Transfuse when platelet count is ≤10 × 10^9 cells/L in hospitalized patients 1, 3
• A single apheresis unit or equivalent is recommended (greater doses are not more effective) 1, 2
• Low-dose platelets (half of standard dose) provide similar hemostasis but may require more frequent transfusions 3

Invasive Procedures

• For central venous catheter placement: transfuse when platelet count is <20 × 10^9 cells/L 1, 2
• For elective diagnostic lumbar puncture: transfuse when platelet count is <50 × 10^9 cells/L 1
• For major elective non-neuraxial surgery: transfuse when platelet count is <50 × 10^9 cells/L 1, 2
• For neurosurgery or central nervous system procedures: conventional threshold is 80-100 × 10^9 cells/L, though supporting data is limited 1

Therapeutic Platelet Transfusion Indications

• For active bleeding with thrombocytopenia: transfuse platelets regardless of count 4
• For patients with platelet counts <10 × 10^9 cells/L due to high risk of serious bleeding 4
• For cardiac surgery patients with cardiopulmonary bypass: transfuse only when perioperative bleeding occurs with thrombocytopenia and/or evidence of platelet dysfunction 1, 2
• Not routinely recommended for nonthrombocytopenic patients undergoing cardiac surgery with cardiopulmonary bypass 1, 2

Special Clinical Scenarios

• Patients with intracranial hemorrhage on antiplatelet therapy: insufficient evidence to recommend for or against platelet transfusion 1, 2
• Patients with inherited platelet function disorders (e.g., Glanzmann's Thrombasthenia): may require additional platelet units or combination therapy with other pro-hemostatic agents 5
• Patients with idiopathic thrombocytopenic purpura (ITP): platelet transfusion is useful only for severe bleeding due to short platelet survival 6

Prophylactic vs. Therapeutic-Only Strategy

• A therapeutic-only platelet transfusion strategy (transfusing only when bleeding occurs) is associated with:
  • Increased risk of clinically significant bleeding compared to prophylactic strategy 7
  • More days with clinically significant bleeding events 7
  • Shorter time to first bleeding episode 7
  • Reduced number of platelet transfusions required 7

Important Considerations and Risks

• Platelet transfusion carries risks including allergic reactions, febrile nonhemolytic reactions, and bacterial contamination 1, 2
• Bacterial sepsis from contaminated platelet units is the most frequent infectious complication from any blood product 1, 2
• Platelets must be stored at room temperature, limiting shelf life to only 5 days 1, 2
• Higher platelet count thresholds (20-30 × 10^9 cells/L) have not been shown to significantly reduce bleeding incidence or bleeding-related mortality 3
• More liberal thresholds may be appropriate for outpatients for practical reasons (fewer clinic visits) 3
• Alloimmunization can lead to poor response to platelet transfusions; consider HLA-matched platelets in these cases 3