Blood Bank I Flashcards
Transfusion Medicine is a term that encompasses what types of medical components?
- blood donation
- component preparation
- serology & infectious disease testing
- transfusion therapy
List the general steps that are part of routine pretransfusion testing.
- Identification on blood & paperwork match
- ABO & Rh(D) typing of recipient & screening of the serum
- If the screen in positive, perform an antibody identification test
- Crossmatch donor blood cells with recipients’s serum (final check)
What type of antigens are ABO?
carbohydrate
Genes for blood type dictate whether an A and or B antigen should be added to what precursor?
H antigen
How do people develop ABO antibodies?
naturally occurring IgM antibodies that do not require previous exposure
usually present by 6 months of age
What aspect of the ABO antibodies make it potentially dangerous to combine blood types?
IgM antibodies fix complement & may cause intravascular hemolysis
How is it possible for a mother to give birth to a child with a different blood type?
IgM antibodies do not cross the placenta, so they do not cause hemolytic disease of the fetus & newborn
What are the main antigens of the Rh system?
D (Rh +), C, c, E, e
What type of antibodies are developed in response to Rh antigens? What is the significance of this?
IgG
may cause delayed hemolytic transfusion reactions
hemolytic disease of the fetus and newborn (b/c can cross the placenta)
IgG antibodies cause what type of hemolysis?
What about IgM?
IgG : extravascular hemolysis (not efficient at fixing complement)
IgM : intravascular hemolysis (better at fixing compliment)
What is hemolytic disease of the fetus & newborn? (HDFN)
have Rh (-) mother
If first baby is Rh (+) - baby is protected because mother has not been exposed to Rh antigen & therefore has not made antibodies against it
At parturition, there will be intermingling of mother & baby RBC, and mom will start forming antibodies
If mom get pregnant again with a RH(+) baby, her pre-formed IgG antibodies can cross the placenta & cause serious damage to the fetus
What is the most severe manifestation fo HDFN?
Hydrops Fetalis
accumulatio
What is Hydrops Fetalis
Causes?
accumulation of clear, watery fluid in the tissue or cavities of the body of the fetus
Causes
- immune mechanisms:
- blood group incompatibilities
- non-immune mechanisms:
- some infections,
- fetal cardiac disease,
- other structural abnormalities
Describe the pathophysiology behind immune causes of Hydrops Fetalis
IgG antibodies cross the placenta & coat the fetal RBC
those fetal RBC are then picked up and destroyed in the fetal liver/spleen
liver & spleen can become enlarged
can go into liver failure & it stops making enough proteins, developing massive ascites
fetuses can also have nucleated (immature) RBC in the peripheral blood
Is hemolytic disease of the fetus & newborn more likely to be caused by Rh incompatibility or ABO incompatability?
ABO – if mother has ever been exposed to one of these antigens, she will also develop IgG antibodies against them, which are able to cross the placenta
What co-morbid conditions are commonly seen in infants born with HDFN?
Jaundice
Kernicterus
What pathology is shown in the provided image? It is most common in what demographic?
Kernicterus
blood-brain barrier is suboptimal due to prematurity or acidosis
What is Kernicterus & what is the clinical presentation?
High levels of unconjugated bilirubin that crosses the blood brain barrier & deposits in the brain
- Cerebral edema
- Bright yellow staining of the brain (b/c unconj. bilirubin)
When is Rh Immunoglobulin administered to patients?
- Given to D-negative pregnant women
- at 28 weeks gestation
- post partum within 72 hours
How does Rh Immunoglobulin work when it is administered to pregnant patients? In what situation is it contraindicated?
anti-D coats the fetal RBC
the coated RBC are removed from the blood by the reticuloendothelial system
this prevents D-negative mothers from making anti-D antibodies
no contraindications, but it is of no value if anti-D antibodies have already formed
What is the difference between Forward Typing & Reverse Typing?
-
Forward Typing
- Patients cells are combined with reagent sera
- info about which ABO antigens are present in patient’s cells
-
Reverse Typing
- Patients serum is combined with reagent cells
- info about which ABO antibodies are present in the patient’s serum
Should have OPPOSITE reactions
Identify which test tube indicates a positive test, negative test & a moderately positive test for agglutination
The provided reactions indicate what blood type?
A positive
How would you grade the following test tubes?
+4 = positive for agglutination
0 = negative for agglutination
What is a DAT and in what situations is it performed?
Direct Antiglobulin Test - detects in vivo attachment of immunoglobulin or complement to red cells
- Used in:
- autoimmune helolytic anemia
- transfusion reaction
- HDFN
What is an Indirect Antiglobulin Test & in what situations is it used?
Detects in vitro attachment of immunoglobulin or complement to red cells
- Used for:
- antibody screening & crossmatching
- antibody identification panels after positive antibody screen
Why do you perform an antibody screen?
- detect unexpected antibodies in patient’s serum - people who receive regular transfusion are susceptible to developing new antibodies
What are the 2 spins performed in an antibody screen & why are each of them performed?
- room temp immediate spin testing detects IgM antibodies
- Testing at 37 degrees C & AHG phases detects significant IgG antibodies
What type of cells are used for antibody screening?
type O with known surface antigens, purchased from a manufacturer
What are the clinically significant antibodies?
- Usually IgG
- React at 37 degrees C
- Kell (K, k)
- Kidd (Jka, JKb)
- Rh (D, E, e, C, c)
What is the “last check” for blood typing before the transfusion is performed?
Crossmatch
confirms ABO typing - sometimes picks up antibodies not detected in antibody screen
When is the crossmatch carried through to 37 degrees with AHG?
if the antibody screen is positive
the immediate spin is done at room temp & if screen is good, then this is usually enough
What are the 3 emergent crossmatch options?
Include how long it takes to receive each transfusion & specifics of administration for each type.
-
Uncrossmatched Blood - O-positive or O-negative
- available in 5 min
- ONLY O-neg to young females & females of childbearing age
- O-positive is okay for males & postmenopausal females
-
Emergency Type-Specific
- available in 10 min
- ABO & Rh typing done, but no antibody screen yet
-
Type Specific with full crossmatch
- available in 30 min, if no unexpected antibodies
- ABO, Rh, antibody screen & crossmatch are done
What are the two type of pre-operative blood orders?
-
Type & Screen Only
- ABO, Rh, & antibody screen but no crossmatch
- ordered when blood use during surgery is not expected
-
Type & Crossmatch
- ABO, Rh, antibody screen & crossmatch have been performed – ready for transfusion
- order when blood is expected to be used during surgery / when unexpected antibodies on screen
Answer the following questions with reference to packed red blood cells:
Does it require a crossmatch?
Standard volume?
How long can it be stored & in what conditions?
How quickly must it be used once it leaves the Blood Bank?
Requires crossmatch
~300mL
May be stored for up to 42 days at 1-6 degrees C; may be leukodepleted
must be transfused within 4 hrs of leaving Blood Bank
Answer the following questions with reference to packed red blood cells:
Does it require a crossmatch?
Standard volume?
How long can it be stored & in what conditions?
How quickly must it be used once it leaves the Blood Bank?
Requires crossmatch
~300mL
May be stored for up to 42 days at 1-6 degrees C; may be leukodepleted
must be transfused within 4 hrs of leaving Blood Bank
By how much should 1 unit of packed red blood cells change the hemoglobin / hematocrit?
raise hemoglobin by 1 g/dL or hematocrit by 3%
What is the concern with massive transfusions & what risks is it associated with?
>10 units
may dilute coagulation factor levels & platelets → bleeding
risk: hepatitis, allo-immunization, other rxns
What is the purpose of leukocyte depleted RBCs?
Special Type of RBC Transfusion
decreases risk of febrile non-hemolytic transfusion reaction
What is the purpose of frozen deglycerolized RBCs?
Special types of RBC transfusion
for rare blood types & military use
can be stored frozed up to 10 yrs - expires w/in 24 hrs of thawing and deglycerolization
What is the purpose of washed RBCs?
Special type of RBC transfusion
washed 3x to remove platelet, plasma & 90-99% WBC - expires 24 hrs after washing
for IgA deficient patients & others with severe reactions to plasma proteins
CMV-negative blood products are reserved for what groups of people?
- Patients with the highest risk of contracting CMV infections
- intrauterine transfusions, neonates, infants <4 months
- allogeneic bone marrow transplant recipients
- liver transplant recipient <18
- recipient of lung, heart, heart/lung transplants
- cardiovascular surgery patients under 12 months
- immunocompromised patients (on request)
