Revisitation of the clinical indications for the transfusion of platelet concentrates.

Platelet transfusion is indicated when the expected benefits of increasing the number of functional platelets in the patient's circulation outweigh the potential risks generated by exposing the patient to allogeneic, manipulated and stored blood products such as platelet concentrates. Although reassuring evidence has been collected indicating that current risks associated with blood transfusion are lower than those of several voluntary and involuntary human activities, balancing benefits and risks of platelet transfusion may not be easy in a proportion of patients and in a number of conditions. To facilitate this task, guidelines have been developed, with particular attention to cancer patients. As witnessed by the most recent guidelines, over the last few years there has been a progressive, although not absolute, consensus on: (i) the routine use of platelets as a tool to prevent hemorrhage in oncohematology (the so called 'prophylactic approach') as opposed to limiting platelet transfusion to actual bleeding episodes (the so-called 'therapeutic approach') and (ii) lowering the trigger for prophylactic platelet transfusion in stable oncohematology recipients from 20 x 109 to 10 x 109 platelets/L. This has been accompanied by a reduction of platelet use per oncohematology patient of about 20%, an important outcome in view of the progressive increase of platelet demand due to more aggressive therapy in cancer patients. In selected clinical conditions, specific triggers ranging from 30 x 10(9) to 100 x 10(9) platelets/L have been recommended, with higher values when surgical procedures are required for the patient's treatment. Indications and trigger values proposed in the guidelines must be considered within the context of careful clinical evaluation of each patient, with a clear appreciation of the power of discrimination of automated platelet counters at low counts, and of the quality and local availability of platelet products for emergency.