Donor Screening and Deferral.

The maintenance of an adequate and safe blood supply begins with choosing the right donor at the right time. The evolution of donor screening has been shaped by experience, donor satisfaction, and the ever-challenging emergence of relevant infectious diseases. Screening donors has been standardized over the past 6 decades to protect donor and recipient safety. In this review, we outline, define, and simplify the requirements to assess and defer donors with a focus on recent and ongoing changes to provide up to date information on donor qualification and current challenges in maintaining the blood supply.