We currently have a policy that a unit of blood or product should be transfused within 4 hours. Does anyone have guidelines as to how much time can elapse between issue and hanging the unit of blood? A nurse returned a unit a few weeks ago stating she would not hang the unit because it was issued over 30 minutes ago. Needless to say the product was wasted. I have not been able to find a standard governing the time between issue and hanging of a unit. Any one have a procedure or standard for guidance?