Splenic platelet-sequestration following routine blood transfusion is reduced by filtered/washed blood products.

The mean fall in the platelet count following 23 routine transfusions of 3-5 units packed cells for anaemia was 32.5%. This was significantly reduced to 12.5% in 15 similar transfusions through a 40 microns microaggregate filter (P less than 0.01) and to 4.6% following five transfusions through a polyester fibre filter (P less than 0.005). In 10 transfusions with frozen or polyester fibre filtered, washed red cells, the decrease in platelet count was 4.2% (P less than 0.001). A study of 111In-oxine labelled autologous platelets in nine patients indicated that the fall in platelet count was due to increased splenic sequestration. Since thrombocytopenia following routine transfusion is reduced by procedures which filter the packed cells, the decrease in platelets is probably caused by their adherence to infused microaggregate debris causing their premature removal from the circulation. Patients with preexisting thrombocytopenia who receive red cell transfusions for anaemia, should therefore receive blood products depleted of microaggregate debris in order to avoid exacerbation of thrombocytopenia and haemorrhagic complications.