We transfuse approx 150 units per month. Our not-returned rate along with our 'returned but incomplete' is less than 2%. This is alot of work, but consistency makes it easier. Our techs review slips in the AM as part of 'morning routine' and inventory resolution. They make calls to the floors, send notices, and if needed go to the chart. With what I think are good numbers, the job now is not that time consuming. I suggest you meet with nurse educators/managers for a re-education of the importance and regulatory requirement of unit tag return, times, signature, etc. I have in the past, sent 'notices' along with the unit at time of issue. You can make them up in word. Just remind the RN to return the completed unit tag following transfusion etc,etc. I would change the notices from time to time for variety. It really does work! We also have a 'stamp' for the Blood bank copy with the reminder . I hope the suggestions help.