A 65-year-old Caucasian female presents to the emergency department with progressive shortness of breath on minimal exertion and fatigue. She was diagnosed with myelodysplasia two years ago, and has been receiving supportive therapy with frequent RBC transfusions. Her last transfusion was 3 months ago. She experienced an episode of severe pneumonia one year ago that required hospitalization and IV antibiotic therapy. She is taking no medications currently and has no known allergies. Her blood pressure is 120/70 mmHg and heart rate is 95/min. Physical examination reveals pallor. Systolic murmur with intensity of II/VI is heard over the cardiac apex. Laboratory findings are significant for hematocrit of 24% and hemoglobin level of 5.7 mg/dL. You consider RBC transfusion in this patient. Blood grouping and cross-matching are done, but the blood bank is unable to find suitable blood. This is the first time such an incompatibility has occurred. What is the most likely reason for this incompatibility?

Question

A 65-year-old Caucasian female presents to the emergency department with progressive shortness of breath on minimal exertion and fatigue.  She was diagnosed with myelodysplasia two years ago, and has been receiving supportive therapy with frequent RBC transfusions.  Her last transfusion was 3 months ago.  She experienced an episode of severe pneumonia one year ago that required hospitalization and IV antibiotic therapy.  She is taking no medications currently and has no known allergies.  Her blood pressure is 120/70 mmHg and heart rate is 95/min.  Physical examination reveals pallor.  Systolic murmur with intensity of II/VI is heard over the cardiac apex.  Laboratory findings are significant for hematocrit of 24% and hemoglobin level of 5.7 mg/dL.  You consider RBC transfusion in this patient.  Blood grouping and cross-matching are done, but the blood bank is unable to find suitable blood.  This is the first time such an incompatibility has occurred.  What is the most likely reason for this incompatibility?

Quizplus · Accepted Answer

Explanation: After blood is ordered for transfusion, the following compatibility testing is usually performed. First, the patient's ABO and Rh types are determined. After this, the patient's serum is screened for unexpected antibodies, a procedure called pretransfusion antibody screening. Pretransfusion antibody screening is intended to detect any of all clinically significant RBC antibodies. If negative, the patient can be safely transfused. If positive, further investigation is usually warranted to evaluate the identity of the antibody. The major problem that leads to difficulties finding cross-matched blood in patients with a history of multiple transfusions is alloantibodies (e.g., in patients with sickle cell anemia or myelodysplasia). The most commonly implicated RBC antigens in that case are E, L and K. Moreover, these patients tend to develop multiple alloantibodies that make finding compatible blood even more difficult. (Choices C and E)Finding ABO and Rh-compatible blood is usually not a big challenge. (Choice A)Autoantibodies are less likely to cause difficulties in cross-matching in this patient; they are commonly implicated as a cause of the incompatible cross-match in patients with autoimmune anemia and taking certain drugs (e.g., methyldopa and procainamide). (Choice D)HLA allosensitization increases risk of graft rejection in patients awaiting organ or bone marrow transplantation and platelet refractoriness in those requiring subsequent platelet transfusion support. Remember that RBCs do not express HLA antigens. Educational Objective: The major problem that leads to difficulties finding cross-matched blood in patients with a history of multiple transfusions is alloantibodies.

A 65-Year-Old Caucasian Female Presents to the Emergency Department with Progressive