INTRODUCTION

A major goal of transfusion medicine practice has been to reduce the risk of transfusion-transmitted infection to as low a level as possible [1,2]. In order to approach the desired level of zero risk from transfused allogeneic blood, multiple layers of safety are needed. Methods used in attempting to maximize safety from donated allogeneic units include donor selection criteria, donor medical history interview, the confidential unit exclusion (CUE) option, donor deferral registries, laboratory testing of donated units, donor initiated telephone call backs, and modification of the blood unit after collection, either by leukocyte removal or physicochemical procedures for pathogen inactivation [3,4].

In addition to assuring that the donated unit will not cause any adverse consequences for transfusion recipients, the evaluation of each prospective blood donor includes procedures to assure that the donor will not suffer any adverse reactions from the donation itself [5], or from hematopoietic growth factors that may be employed to facilitate such donations [6].

Over the past three decades, procedures used to evaluate donors have changed dramatically. The increased awareness of potential spread of infectious disease by blood transfusion has resulted in much more elaborate donor screening for the purpose of protecting the transfusion recipient [5]. At the same time, experience from autologous donation programs has lessened the concern about adverse donor reactions [7]. (See "Preoperative autologous blood donation".)

In the last decade, standard serological testing of donated blood for Human Immunodeficiency Virus (HIV) and Hepatitis C Virus (HCV) has been supplemented by the addition of nucleic acid testing of pools of donations for HIV and HCV RNA, which allows for detection of additional infectious units [8]. The current per unit risk estimate for acquiring HIV from transfusion is one in 1.5 to one in 2.1 million and for HCV is one in one million to one in two million [9,10].

Prior to 2010, risks for Hepatitis B Virus (HBV) were estimated to range from one in 58,000 to one in 269,000. Since that time, as the result of additional donation testing, these risks are now estimated to range from one in 205,000 to one in 355,000 [9,11-13]. Risk for human T-lymphotropic virus (HTLV) is estimated to be about one in two million when the older published risk estimate (one in 641,000) is adjusted for the fact that only one-third of potentially infectious units actually transmit HTLV infection, due to loss of viable virus upon blood component storage [12,14].