Platelet transfusions (providing people who haemorrhage with platelets containing fresh blood), may not be as successful as the medical fraternity initially believed.

This type of transfusion has been considered invaluable at stemming bleeding from defective platelets (thrombocytopenia) and reducing haemorrhage during leukaemia chemotherapy.
Platelets in Britain are gathered from more than one donor, increasing the possibility that the recipient might form antibodies to the various blood components. Platelets need to be stored at room temperature where they can cluster, but this changes the cell shape and results in poor post-transfusion function. The temperature also encourages the growth of bacteria, which can cause fatalities.

Doctors at the Beth Israel Medical Centre in Boston suggest that the level to prevent bleeding is safer at a platelet count of 10,000 per cubic millimeter, rather than the present 20,000 per cubic millimeter. No one has died from trials at the newer level, and researchers claim it has resulted in a one-fifth reduction in the number of platelet transfusions.

In the US, apheresis, an expensive method of collecting many more platelets from a single donor, is proving very successful (N Engl J Med, 1997; 337: 1914-5).