Blood typing and isoimmunization

Question 1

Alleles encode specific cell membrane Carbohydrates or proteins on RBCs called _____

Answer 1

antigens

Question 2

Antigens/Agglutinogens are
_____ on the surface of the
RBCs and can cause agglutination
(clumping) of RBCs during transfusions

Answer 2

carbohydrates

Question 3

_____ – gamma globulins produced in the lymph and bone
marrow, IgG “antibodies”

Answer 3

Agglutinins

Question 4

At birth, the quantity of agglutinins in the
plasma is essentially _____

Answer 4

zero

Question 5

____ months after birth, infants will begin
to produce agglutinins

Answer 5

2-8

Question 6

Peak titer of agglutinins is at ____ yo

Answer 6

8-10

Question 7

From birth, we are exposed to “A-like” and “B-like” carbohydrate
antigens from a variety of sources – _____. What occurs from this?

Answer 7

Food, bacteria, other substances
As a result, we develop antigen-specific “natural” IgG and IgM immunoglobulins even in the absence of blood transfusions

Question 8

Relative Frequency of Different Blood Types

Answer 8

● O – 47%
● A – 41%
● B – 9%
● AB – 3%

Question 9

A and B show ____

Answer 9

co-dominance

Question 10

There are ____ different types of Rh antigens (called Rh Factors)

Answer 10

six

Question 11

The ___ antigen is widely prevalent and considerably more antigenic than the other Rh Antigens

Answer 11

D Antigen

Question 12

“____” if the D antigen is absent

Answer 12

Rh-

Question 13

“____” if the D antigen is present

Answer 13

Rh+

Question 14

______ (or alloimmunization) is when our bodies have an immune response to nonself antigens from members of the same species

Answer 14

Isoimmunization

Question 15

Universal recipient

Answer 15

AB

Question 16

Universal Donor

Answer 16

O

Question 17

During subsequent pregnancies, the mother’s anti-Rh agglutinins cross the
placenta to an Rh-positive fetus resulting in various forms of ______ (Hemolytic Disease of the Newborn)

Answer 17

Erythroblastosis Fetalis

Question 18

Erythroblastosis Fetalis (hemolytic disease of the newborn) causes _____

Answer 18

○Anemia:Results in over production of erythroblasts from the bone marrow
○Jaundice: With significant buildup of bilirubin may result in Kernicterus – neurologic syndrome when unconjugated
bilirubin is deposited in the basal ganglia
○ Hydrops fetalis: Hepatosplenomegaly, ascites, edema, pleural/cardial effusion
○ Death

Question 19

______ – neurologic syndrome when unconjugated bilirubin is deposited in the basal ganglia

Answer 19

Kernicterus

Question 20

Prevention for Erythroblastosis Fetalis

Answer 20

RhoGAM - Rh(D) Immunoglobulin Globin
(Anti-D Antibody)
○ Given to the mother IM at 28 to 30
weeks gestation and 72 hours
postpartum

Question 21

RhoGAM MOA

Answer 21

In an RhD-negative individual
RhoGAM suppresses the immune
response and antibody formation
of RhD-positive red blood cell

Question 22

RhoGAM Indication

Answer 22

D-negative mother with a fetus that is, or may be, D-positive
■ An RhD-incompatible pregnancy is assumed
● If the fetus/baby is either RhD-positive or RhD unknown or if the father is either RhD-positive or RhD
unknown.
● Use is not needed if the father or baby is conclusively RhD-negative.

Question 23

RhoGAM contraindications

Answer 23

○ History of anaphylaxis or severe hypersensitivity reaction to human
immune globulin
○ Autoimmune hemolytic anemia
○ Hemolysis, pre-existing or at high risk
○ IgA deficiency with antibodies against IgA; potential for severe
hypersensitivity & anaphylactic reactions

Question 24

RhoGAM Side effects

Answer 24

○ Injection site pain (0.5% )
○ Nausea (0.7% )
○ Extravascular hemolysis (Mild) (21% ) → low hemoglobin
○ Dizziness (0.5% )
○ Headache (0.5% to 14.3% )
○ Malaise (0.5% )
● Pregnancy: Category C
● Breast Feeding: Minimal risk

Question 25

RhoGAM adverse effects

Answer 25

○ Hematologic: Intravascular hemolysis
○ Immunologic: Anaphylaxis (rare)
○ Renal: Renal failure, acute

Question 26

RhoGAM monitoring

Answer 26

○ Suppression of Rh isoimmunization; Rh-positive red cell clearance is indicative of
efficacy
○ If used for pregnancy - observed for about 20 minutes following administration
○ If used for ITP - observed for 8 hours following administration, UA, CBC baseline
and following administration

Question 27

_____ – Testing for antibodies in the serum

Answer 27

Indirect Coombs Test

Question 28

Type and Cross (Crossmatch)

Answer 28

● Testing to determine if the donor’s and recipients blood are compatible
● ABO and Rh first confirmed, then blood from the donor and recipient
are mixed in a test tube
○ Detects antibodies to other blood group systems
○ Detects antibodies in low titers/those that do not agglutinate easily

Question 29

Type and Screen

Answer 29

● ABO and Rh antibody screen – determination of blood type
● Indirect Coombs Test – Testing for antibodies in the serum

Question 30

Final step prior to transfusion

Answer 30

Type and Cross (Crossmatch)

Question 31

When to Order type & screen vs crossmatch

Answer 31

● Type & Screen
○ Type – ABO and Rh status
○ Screen – Screens patient’s blood for antibodies to other antigens
○ Order if there is any chance that the patient may require blood

● Crossmatch
○ Mixing donor and recipient blood to ensure compatibility
○ Detects antibodies in low titers/those that do not agglutinate easily
○ Order if there is higher risk of transfusion (ask the lab to put the
donation blood on hold)
○ More costly and takes longer (~45 min)

Question 32

When to Order Uncrossmatched Blood

Answer 32

Order if you need stat blood. Call the lab and communicate that you need unmatched O- or O+ blood “stat”