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Transfusion - Post Transfusion Purpura

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Caution

Transfusion of blood and blood products is associated with risks and they should only be administered when the benefits are considered to outweigh these risks. Adverse transfusion reactions occur with 0.5-4% of all transfusions. If a transfusion related adverse event occurs, this should be recorded on the appropriate notification form.

In this circumstance, please contact the Transfusion Nurse Specialist or the Transfusion Medicine Specialist. We emphasise the need for Haemovigilance, which is a national programme aimed at making blood transfusion safer. See also New Zealand Blood Transfusion Medicine Handbook 2008.

Pathophysiology

This is characterised by the development of severe thrombocytopenia approximately a week after blood transfusion. It is a rare condition but potentially lethal.

Platelet destruction occurs when an anamnestic immune response boosts platelet antibodies previously stimulated by pregnancy or transfusion. The resultant thrombocytopenia is due to antibody-mediated destruction of the transfused platelets and the patient's own platelets. In more than 85% of cases, the patients are negative for the platelet antigen HPA-1a and their serum contains anti-HPA-1a. Passive transfer of platelet-specific antibody from donor to patient with subsequent clinical PTP has been reported.

Clinical manifestations

Characterised by the sudden onset of severe thrombocytopenia (platelet count often <10), occuring 5 - 10 days post transfusion. The patient develops petechiae and is at risk of spontaneous bleeding. It is most often seen in females (≈90% of cases), in particular those with a history of pregnancy.

Laboratory testing

Notify blood bank and discuss with the transfusion medicine specialist, as specialised investigations are required. These will reveal anti-platelet antibodies, usually of a defined specificity such as anti-HPA-1a or anti-HPA-2b.

Management

Treatment includes intravenous immunoglobulin 2 gm/kg in divided doses over 2-5 days. Plasma exchange and corticosteroids have been used in the past but are associated with a delay in platelet recovery. The platelet count usually improves over several weeks. During the acute phase, if platelet transfusion is unavoidable, platelets compatible with the patients antibody should be used, although platelet survival is usually impaired. For future transfusions, the patient should receive only blood products from donors negative for the implicated HPA-antigen. Expert advice from an NZBS transfusion medicine specialist or clinical haematologist is needed when managing PTP.

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Document Control

  • Date last published: 16 May 2016
  • Document type: Clinical Guideline
  • Services responsible: National Child Cancer Network
  • Owner: Tim Prestidge
  • Review frequency: 2 years