Optimisation is used to support decisions concerning the required number of donors (either in total or broken down by blood group) and the associated collection and production methods, to minimise the production cost. During the production stage, once the collection process is over, the units are placed in quarantine to assure their validity and then added to the inventory. Outdated units are removed daily, and the inventory levels are revised and ready to process and issue new orders, which are divided as either regular or urgent.