Diabetes
As to whether or not the direct test should be discontinued, Moore answers this question himself when he states that the test offers a final chance to detect ABO incompatibility, which is responsible for 86% of fatal immediate hemolytic transfusion reactions.
Abstract
ing of donor red blood cells, Moore advises that "the ABO group (and the Rh group if the cells are Rh negative) of each donor unit received from a regional transfusion centre need be verified only if units leave the laboratory without any tests for incompatibility having been done". The blood bank staff have no way of knowing which donor units may be issued before compatibility tests are performed. It is therefore prudent to test all donor units as soon as they are received from the Red Cross Regional Transfusion Centre, thus speeding the issuance of such units should they be required before a crossmatch (direct test) is performed. Under the heading "Tests to detect incompatibility" Moore writes that whenever possible the antibody screen (indirect test) is done before the direct test. In the hospital blood transfusion laboratory it is conventional, as Moore states, for the antibody screen and the ABO and Rh grouping to be combined. However, the crossmatch is then set up as soon as the ABO group and Rh type are known, usually in less than 5 minutes. The results of these tests are read together; alloantibodies, if present, are detected at this time. Thus, the transfusion may be delayed. If the indirect test had been performed before the direct test the presence of alloantibodies could be acted on without delaying the transfusion, but only if the test had been performed far enough in advance to permit identification of all the alloantibodies that might be present. Unfortunately, this is seldom possible, and ideal as it may be the routine performance of the antibody screen before the crossmatch is not feasible. Moore states: "A disadvantage of the screening test is that each antibody that is found must be identifled, which takes time." Surely this is the primary purpose of the screening test to detect and subsequently identify alloantibodies, thereby enhancing the safety of the transfusion. As to whether or not the direct test should be discontinued, Moore answers this question himself when he states that the test offers a final chance to detect ABO incompatibility, which is responsible for 86% ofn fatal immediate hemolytic transfusion reactions. Good blood bank records are essential for the provision of safe and speedy transfusions. The following example illustrates the worth of such records. A patient with a ruptured ectopic pregnancy was brought to our emergency department. A request for blood was entered in the computer; when the printed requisition was received by the blood bank it was noted that her blood contained anti-Fya. This alloantibody had been demonstrated 2 years previously. ABO group, Rh type and antibody status, reports become permanent long-term retrieval items once they have been entered in the computer; this information is then printed on all future blood bank requisitions. Consequently, a search for Fy(a-) donor blood was started even before the patient's blood specimen arrived at the blood bank.