As has been discussed earlier, blood collection and inventory could take place either at the hospital or at the regional blood centre. The hospital blood bank operates as an inventory location, to meet the local demand; it will handle storage and issuing transfusion requests for unique blood types for a random number of units (Prastacos 1984). Once a request is received, a matching number of units are identified and removed from free inventory and placed on reserve inventory until they are either used or returned. Unutilised units during their shelf life will be invalid and discarded.