Massive Transfusion Before Blood Type Is Known
A 31-year-old woman is brought to a level 1 trauma center after a motor vehicle collision with a pelvic fracture and active hemorrhage. She arrives in hemorrhagic shock, and the massive transfusion protocol is activated before a blood type is available. Over the first 40 minutes she receives 4 units of group O Rh-negative red blood cells and 4 units of group AB plasma. Her type and screen is completed shortly afterward: she is group A Rh-positive with a negative antibody screen. The blood bank has group A Rh-positive red cells, group A plasma, group AB plasma, and group O Rh-positive and Rh-negative red cells available. The trauma surgeon asks whether it is safe to switch to group A red cells and group A plasma and whether the earlier O-negative units could have caused a hemolytic reaction. The patient is still bleeding and has received 6 units of crystalloid; fibrinogen is 120 mg/dL.
1. Was the use of O-negative red cells and AB plasma appropriate before the type was known? Explain the ABO compatibility.
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Yes. Before the patient's ABO type is known, group O Rh-negative red cells are the standard choice because O red cells lack A and B antigens and can be given to a recipient of any ABO type. Group AB plasma is the universal plasma because it lacks anti-A and anti-B antibodies and can be given to any ABO recipient. In this patient, the O-negative red cells are compatible with her group A red cells because there are no A or B antigens on the donor red cells for her anti-B to react with. The AB plasma is also compatible because it contains neither anti-A nor anti-B. The small amount of plasma in the O red cell units may contain anti-A or anti-B, but the volume is small and clinically insignificant in massive transfusion. The earlier units would not be expected to cause an ABO hemolytic reaction.
2. What products should be given now, including red cells, plasma, and platelets, and what about Rh?
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Once the patient is typed as group A Rh-positive, switch to group A Rh-positive red cells and group A plasma. Group AB plasma remains acceptable if group A plasma is unavailable. For platelets, ABO-identical products are preferred, but group A or group AB platelets are compatible; group O platelets may be used if necessary, recognizing that they may contain anti-A that could affect a group A recipient, especially with high-titer products. Because the patient is Rh-positive, Rh immune globulin is not indicated. If she were Rh-negative and of childbearing potential, Rh-negative red cells and Rh immune globulin would need to be considered. Continue monitoring fibrinogen; at 120 mg/dL with ongoing hemorrhage, cryoprecipitate or fibrinogen concentrate may be indicated according to the massive transfusion protocol.
3. What laboratory monitoring and transfusion reaction workup are indicated?
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Monitor hemoglobin, platelet count, prothrombin time, activated partial thromboplastin time, fibrinogen, ionized calcium, lactate, and acid-base status during the massive transfusion. Citrate toxicity can cause hypocalcemia, so ionized calcium should be checked and replaced. Watch for dilutional coagulopathy, hypothermia, and hyperkalemia. If there is concern for a hemolytic reaction, perform a clerical check, repeat the ABO type, inspect the post-transfusion plasma for hemolysis, and obtain a direct antiglobulin test, lactate dehydrogenase, haptoglobin, and bilirubin. In this case, an ABO hemolytic reaction from the O-negative red cells and AB plasma is unlikely, but a reaction to a later unit or a non-ABO antibody remains possible. Any suspected reaction should be reported to the blood bank and evaluated before further transfusion.