This is a reaccuring issue in our lab, we have a patient that previously had a positive anitbody screen, and now it is negative. Our debate is, if the patient hasn't been stimulated in the last 3 months (ie transfusion, pregnancy or surgery, then the outdate should be 3 weeks. Others say, there is a history, it should only be good for 72 hours. Has anyone else run into this issue? Where can I find the literature to support this? Thanks