Fung: Transfusion Medicine Flashcards
At a blood bank, tubes of blood are first spun to look for (blank). Next, they are tested via the IAT phase to detect RBCs coated with (blank). Which step in this process is more often significant?
In tube testing, the blood will first undergo immediate spin to look for IgM antibodies - these are usu insignificant; next is the IAT phase in which RBCs are coated with IgG +/- complement and antibodies that react and cause agglutination are more often significant
What is the difference between a direct antiglobulin test and an indirect antiglobulin test?
DAT: in vivo - look for RBCs already bound by antibody
IAT: in vitro - look for antibodies present in the patient’s serum
an inherited character of the red cell surface detected by a specific alloantibody
blood groups
How many blood groups are there currently?
339
List some red cell antigens that we use clinically
ABO Rh (D) Secretor Lewis (A or B) Kell (K or k) Duffy (FyA or FyB) Kidd (JkA or JkB) I (I or i) MNS P
When are blood groups clinically significant?
when they can cause hemolytic transfusion reactions or hemolytic disease of the newborn/fetus
Most significant RBC antibodies are (blank), (blank), and require (blank)
IgG (can cross the placenta)
warm reactive
previous exposure
Most insignificant RBC antibodies are (blank), (blank), and (blank) occurring
IgM; cold reactive; naturally
The H antigen on RBCs is further modified to make (blank) and (blank) antigen. (blank) antigen has no further modification of H antigen.
A; B; O
T/F: Your ABO genotype is determined by 3 co-dominant alleles on the long arm of chromosome 8
false; chromosome 9
On what other cells/tissues besides RBCs are ABO antigens found?
platelets endothelium kidney heart lung bowel pancreas
When are ABO antigens present on fetal RBCs?
by 6 weeks of gestation; reach adult levels by age 4
Most common blood type in Caucasians, AA, Asians, and Native Americans?
OO
What is the Bombay blood type?
Lack of H, A, and B antigens due to lack of H and Se genes
How do you get antibodies to opposing blood types? At what age do these appear?
they are naturally occurring; appear at 4 months of age, reach adult levels at 10
ex: Anti-A, Anti-B, Anti-A,B
Which blood type is at the highest risk for hemolytic disease of the fetus/newborn?
Type O
When you test a patient’s serum, you use forward typing and reverse typing. How do these differ?
forward typing: determines antigens present on patient’s or donor’s cells (ex: If type A, will test + for Anti-A antigen)
reverse typing: determines antibodies in patient’s or donor’s serum or plasma (ex: if type A, will test + for B cells)
Red cell grouping
Patient’s red cells agglutinated by test anti-A, anti-B antibodies
Forward typing
Serum grouping
Patient’s serum or plasma agglutinated by test A1 and B RBC
Reverse typing
There are two Rh genes. What are they? Which is very immunogenic?
RH (D) and RH (C/c, E/e);
D makes the most antibodies and is very immunogenic
Will HDFN occur during a mother’s first pregnancy?
no, unless the Rh- mother was previously transfused and exposed to Rh+ blood
How can you prevent HDFN if you know a mother is Rh- and her fetus is Rh+?
Give RhIG (preparation of anti-D antibody) to the mother at 28 weeks gestation and <72 hrs after birth
When should you NOT administer RhIG to a mother?
if the Rh- mother already has anti-D antibodies
Rh+ mothers
Rh- mom with Rh- baby
How much RhIG should you administer?
300micrograms (1 vial) per 30mL of D+ whole blood
or
300micrograms per 15mL of D+ RBCs
