The next stage would be about the handling of the collected blood units, although sometimes specific collection methodologies enable the collection of platelets directly from the donor. Models at this stage are focused either on one type of product or multiple products; with the aim to reduce cost, optimise storage capacity, and minimise shortages and wasted unites. Haijema and van Dijk (van 2009) developed a Markovian model to support decision making on production and inventories of platelets. Multiple periods, special periods such as weekends and different types of demand are included in the model. Dynamic programming and local search algorithms were used as solution methods, depending on the problem size.