As Malcolm stated, if seronegative blood products are not available, using leukoreduced products is second best for reducing the chance of a CMV infection. We had a patient receive 50 units of leukoreduced blood before the doctor decided to do an allogenic stem cell transplant and he tested her for CMV IgG antibodies. I was truly surprised when it came back negative. Leukoreduction works! As to irradiation, this prevents graft vs host disease and is necessary for patients receiving blood from first degree family members, BMT or HSCT or intrauterine transfusions.