[Delayed hemolytic transfusion reaction caused by an anti-U].

Delayed hemolytic transfusion reactions due to anti-U are rare, only two (2) cases having been reported in the literature. We now report a third case: a multiparous black woman without any transfusion history was admitted to hospital for severe microlytic anemia (31 g/l). The patient was group AB negative, the direct antiglobulin test was negative and an anti P1 cold allo-antibody was present in her serum. Five A, Rh negative, P2 packed red cells were cross-marched with the sample obtained at admission on January 8, 1988. She was transfused on January 8, 9, 10, 11 and 12. On the 12th of January her hemoglobin level reached 125 g/l. On January 13, the patient presented clinical signs of hemolysis and her hemoglobin fell to 60 g/l within 24 hours. On January 15, the direct antiglobulin test was positive and an antibody found in her serum was reactive with all the red cells of the commercial panel. The sample was referred to our red cell serology reference laboratory. The phenotype of the pre-transfusion sample was found to be Fy(a-b-) M, N, S-s-U-. An anti-U was detected in the eluate and the serum. The patient was transfused with two (2) units of O-P2, U-red cells obtained from the American Red Cross, Syracuse, and her hemoglobin reached 90 g/l within 48 hours. This is the third reported case of a delayed hemolytic transfusion reaction due to anti-U. This case illustrates the need to perform cross-matches with samples obtained within 48 hours of the scheduled transfusion for patients who have been transfused with blood in the preceding 3 months. Also, this case emphasises the need to recruit U negative blood donors for the Canadian rare donor file.