10 Flashcards
A semi-quantitative method used to determine the concentration of Ab in a serum sample
Ab Titer
Ab titers use a A) twofold dilution B) fourfold dilution C) sixfold dilution D) eightfold dilution
A) twofold dilution
Results from titers are expressed as __________ from the tube with the _________ dilution showing agglutination.
Reciprocal; greatest
What are some reasons to perform antibody titers?
- Prenatal studies
- Ab identification
- Separating multiple Ab that contain more than one specificity
What is the most common reason for an Ab Titer ?
Prenatal studies
When undiluted, what does Autoanti- I react with? at higher titers?
Adult and cord blood RBCs(undiluted)
ONLY adult cells (higher titers)
Refers to the volume of the substance to be diluted in a total volume of the final solution and is an expression of concentration.
A dilution
What principle is used when testing titers?
Saline IAT principle
What is a Master Dilution ?
procedure that gives more accurate results than individual dilutions for a single set of titration tests because measurements are more accurate with large volumes
How many tubes are used when dealing with HDN?
12 tubes
What kind of pipette is used?
Volumetric pipette
TRUE OR FALSE:
Place 0.5ml saline into tubes 1-10 with a volumetric pipette
False; tubes 2-10
TRUE OR FALSE:
Homozygous will show stronger results that heterozygous.
True
How to we read tubes for results?
From least reactive to most reactive
How many times to we wash cells ? A)2 times B)4 times C)3 times D)5 times
B) 4 times
What is RhIG?
The only preventative method for HDN due to anti-D
When is RhIG given? Why?
At standard times throughout pregnancy and after an accident or miscarriage; to minimize the occurrence of anti-D formation that can result in immunization
How much RhIG is given per dose ?
300ug
_______ dose counters ____ of D Pos fetal blood
300ug ; 30ml
Why would a Rh neg mother NOT receive RhIG?
- infant is known to be Rh neg
- Mother didn’t receive RhIG during first pregnancy and produced her own anti- D
RhIG therapy should be given within ___ hours of delivery
72
How long can Anti- D be detected after therapy?
5 months
What could failure of RhIG be due to?
- administered after 72 hours
- Improper dosage
What is the Rosette test ?
Screening/qualitative test for Rh Pos fetal blood in mother’s circulation
What is Acid Elution (Kleihauer-Betke)?
quantitative test that detects presence of Rh Pos or Rh Neg fetal RBCs in maternal circulation
How do you know if a Rosette Test is deemed positive?
Forms rosettes around D Pos fetal cells
Rosette test detects ____ or more to be positive
10ml
What is this formula?
(% / 100) x 5000ml= fetal blood
fetal blood / 30ml per dose RhIG=doses
Kleihauer- Betke Calculation (Fetal Maternal Hemorrhage)
What is Amniocentesis used to evaluate?
- intrauterine hemolysis
- fetal condition
- severity of HDN
What are two indicators for performing amniocentesis?
- Anti-D Titer at or above 16-32
- history of previous pregnancy with HDN due to anti-D
What negative effects can amniocentesis cause?
- fetal maternal hemorrhage
- increase HDN severity
- immunize against other Ag
Amniocentesis results are used to decide between ___________ transfusion or delivery.
intrauterine
May be used to treat severe anemia and prevent death in utero
Intrauterine transfusion
When is intrauterine transfusion done?
After 20week gestation
What are the blood requirements for intrauterine transfusion?
- O neg
- negative for Ag matching Ab in mother’s blood
- irradiated
- CMV Neg
- Lack Hemoglobin S
- freshest possible , no more than 7 days
- volume transfused depends on f
- fetal size
- route
- initial hematocrit
- gestational age
