Practice questions answers Blood transfusion I

Practice questions answers

Blood transfusion I

© Jun Wang, MD, PhD

 

1. C. Forward typing is to mix patient’s RBCs with anti-A and anti-B reagents. Agglutination to either or both reagents confirms the presence of these antigens on patient’s RBCs. Reverse typing is to mix patient’s serum with reagent A and B cells. Agglutination to either or both cells confirms the presence of anti-A or anti-B or both. This patient has agglutination with anti-B but not anti-A, confirmed RBCs have B-antigen, but not A-antigen. Reverse typing confirmed the presence of anti-A but not anti-B in his serum. This pattern is consistent with type B. Type A RBCs will have agglutination with anti-A reagent, but not anti-B reagent. Type A serum will agglutinate B cells but not A cells. Type AB RBCs will have agglutination with both anti-A and anti-B reagents, while type AB serum will not agglutinate A or B cells. Type O RBCs will not agglutinate with either anti-A or anti-B reagents, while its serum will agglutinate with both A and B cells. Bombay type RBCs lack H antigen and the serum has anti-H. Lack of H antigen results the same pattern as type O in forward and reverse typing using A and B reagents. However anti-H in Bombay type serum will agglutinate any cells with H antigen, including A, B, AB, and O cells. The reaction with O cells is seen in agglutination with all reagent cells in routine antibody screening tests, which typically use O RBCs with various other surface antigens, including Rh, MNS, etc. 

2. D. This patients has a low hemoglobin with active bleeding, indicative of transfusion of RBCs of the matched type. Since this patient is type B, he will need type B RBCs. Fresh frozen plasma and platelets are used to replace coagulating factors or platelets in patients with coagulopathy or severe thrombocytopenia. This patient does not have coagulation factor deficiency, as shown by his normal coagulation panel. His platelet count is within normal range. So she does not need plasma nor platelet at this stage. Type O red cells can be used in all recipients, but only when matched RBCs are not available, or in emergencies when blood type of the patient is not known. 

3. B. ABO type has codominant inheritance. A allele results in A antigen, and B allele results in B antigen. Presence of both A and B alleles is seen in type AB (AB) and lack of both alleles is seen in type O (OO). Type A can have either 1 (AO) or 2 (AA) A alleles. Type B can have either 1 (BO) or 2 (BB) B alleles. This patient is type B. His father is type O and does not have A nor B alleles. The patient must have only 1 B allele (BO) inherited from his mother. The blood type that has B allele include B (BO or BB) or AB (AB). 

4. E. See discussion of question 1. 

5. E. The patient’s has mild anemia and does not need RBC. However, his prolong PT and aPTT is consistent with coagulopathy. His history of alcoholic hepatitis, in the setting of prolonged PT and aPTT that can be normalized by mixing studies, is highly suggestive of liver disease associated coagulopathy with multiple coagulation factor deficiency. ABO matched fresh frozen plasma is commonly used to correct these coagulation factor deficiency. Also see discussion of question 2. 

6. E. See discussion of question 3. 

7. A. ABO and Rh typing need to be performed for woman during their first trimester of pregnancy to assess the risk of ABO and Rh incompatibility that might result in hemolytic disease of the fetus and newborn. Direct Coombs test examine antibodies or complements attached to RBC surface, and is indicated when immune hemolysis is suspected. Hemoglobin electrophoresis is indicated when hemoglobin abnormalities are suspected. This woman has unremarkable past medical history so that she is not likely to have hemoglobin abnormalities. Iron studies are used to diagnose iron deficiency anemia. Serum lead levels will be elevated in patients with lead poisoning, including lead associated anemia, a type of sideroblastic anemia. This woman has no evidence of anemia. 

8. B. See discussion of question 1. Negative Rh factor testing is consistent with Rh- phenotype. 

9. A. This woman is Rh-. Her fetus might be Rh+, due to paternal Rh+ blood type. Rh antibody  screening need to be performed for woman during their first trimester of pregnancy to assess the risk of ABO and Rh incompatibility that might result in hemolytic disease of the fetus and newborn. Anti-Lutheran is usually clinically insignificant. The mother is type AB and will not have anti-A or anti-B. Direct Coombs test examine antibodies or complements attached to RBC surface, and is indicated when immune hemolysis is suspected. 

10. B. Anti-Rh is commonly IgG that can cross placenta and cause hemolytic disease of the fetus and newborn if the fetus is Rh+. See discussion of question 9. The mother is Rh-, and anti-D will not cause hemolysis since she has no D antigen on her RBCs. 

11. C. Rhogam is used to prevent formation of anti-D. See discussion of question 9. Folate and iron supplementation might be needed, but not for the risk of Rh incompatibility. There is no indication for plasma transfusion. See discussion of question 2. 

12. A. This patients has ABO typing similar as O. However, agglutination with antibody screening cells, usually O cells, suggestive the presence of anti-H, as seen in Bombay group. Anti-H lectin test is used examine the lack of H substance on Bombay type RBCs. Also see discussion of question 1. Direct Coombs test examine antibodies or complements attached to RBC surface, and is indicated when immune hemolysis is suspected. Indirect Coombs test is used to detect antibodies in patient’s serum. Repeat ABO typing since there is no discrepancy in the initial ABO typing. Titer of anti-A are not helpful since the patient’s serum agglutinate type O cells that have no A-antigen. 

13. C. Lack of agglutination by anti-H is consistent with lack of H-antigen. Negative Rh factor testing is consistent with Rh- phenotype. Also see discussion of question 1. 

14. D. The anti-H in Bombay type plasma will bind to and cause  immune hemolysis of A, B, AB, and O cells. Therefore only RBCs without H antigen can be used for Bombay patients. This patient is Bombay negative, so only Bombay negative RBCs can be used. Also see discussion of question 2. 

15. D. See discussion of question 1 and 14. 

16. B. This case is characterized by mild hemolysis in a newborn. Positive direct Coombs test is consistent with  immune hemolysis. The mother is O-, and the fetus is A-. There is no Rh incompatibility. However, O type plasma has anti-A and anti-B, with small amount of them are IgG that may cross placenta. So this is most likely a hemolytic disease of the fetus and newborn caused by ABO incompatibility, when a few amount of anti-A IgG cross placenta and cause hemolysis of fetal/neonatal A cells. Parvovirus infection may cause pure red cell aplasia, but not hemolytic anemia. Also seen discussion of question 10. 

17. C. See discussion of question 16. Aplastic crisis is commonly seen in patient with sickle cell anemia and parvovirus B19 infection. Fetal viral hepatitis usually does not have hemolysis. Hereditary spherocytosis is non-immune hemolysis due to abnormal RBC structure protein resulted in increased fragility. Paroxysmal nocturnal hemoglobinuria is characterized by adult onset, triad of hemolytic anemia, pancytopenia and thrombosis, and dark urine at night with clearing during the day. Both of these conditions are negative for direct Coombs test.     

18. D. See discussion of questions 10 and 16. 

19. C. See discussion of questions 16 and 17. 

20. E. See discussion of question 11.

 

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