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Platelet Transfusion Monitoring

  • A pre-transfusion platelet count should be obtained within 24 hours of ordering a platelet transfusion.
  • A post-transfusion platelet count should be done the morning following a platelet transfusion to document the platelet count increment.
  • If two consecutive transfusions yield increments that do not meet the minimum standard for a successful transfusion (see Refractoriness below), the effectiveness of subsequent platelet transfusions should be evaluated by performing a count 10 to 60 minutes after their completion.
  • When HLA-matched or crossmatched platelets are provided for refractory patients (see below), a platelet count within one hour prior to transfusion and 10-60 minutes following completion of transfusion is necessary to evaluate their effectiveness.

Most nonimmune causes of platelet destruction have a greater effect on the 24 hour post-transfusion platelet count than the 10-60 minutes count. Patients with severe infection or DIC can have a relatively normal immediate post-transfusion platelet count, but a low 24 hour platelet count. Massive splenomegaly, shock and massive transfusion are exceptions to this observation. In contrast, patients with platelet antibody have both markedly shortened 10-60 minute and 24 hour post-transfusion platelet counts. Thus, it is usually possible to distinguish alloimmunization (refractoriness) from other complicating medical factors by measurement of platelet counts immediately after transfusion.

Most platelet transfusions are given prophylactically. This means that platelets are transfused to a patient who has thrombocytopenia, but is not bleeding. In stable patients without other factors that increase the risk of bleeding, the goal is to continuously maintain the platelet count above 10 to 20,000/uL. The immediate posttransfusion platelet count should be >20,000/uL and the platelet count obtained 24 hours later should still be >10,000/uL.

In more unstable patients with other risk factors for bleeding (e.g. medications, liver disease, renal failure, prolonged PT &/or PTT, sepsis, DIC), it is more desirable for the immediate posttransfusion platelet count to be >30,000/uL and the 24 hour platelet count to be >20,000/uL.

Overt bleeding will be controlled in nearly all thrombocytopenic patients if the posttransfusion platelet count is 40,000/uL or higher. In contrast, bleeding diminishes in only about one third of patients when the posttransfusion platelet count remains <20,000/uL. If the posttransfusion platelet count is not sustained, bleeding will resume when the platelet count falls below 10,000/uL. Therefore, the platelet count needs to be maintained above 10,000 to 20,000/uL for at least 24 hours.

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