Blood Bank Exam 5 Flashcards
Icterus gravis
Jaundice
Erythroblastosis fetalis
Immature RBCs in circulation
Hydrops fetalis
Generalized term for edema in fetus/neonates
What are the various names of HDFN?
Hydrops fetalis, Icterus gravis, Erythroblastosis fetalis, Anemia of the newborn
What is the most severe form of HDFN? Least severe?
Rh most severe
ABO lease severe
Three main causes of HDFN
Rh, ABO, and other RBC antigens
What are the four conditions that must be met for HDFN to occur?
- Mother must be exposed to foreign antigen from pregnancy
- Exposure to foreign antigen results in immunization and antibody production
- Antibody has to have the ability to cross the placenta (IgG) in sufficient concentrations to cause rbc destruction
- Infant must possess the corresponding antigen and it must be well developed
Placental function
Exchanges oxygen, nutrients, waste products; serves as a barrier between fetal and maternal circulation
Can Rh/other non-ABO antibodies cause HDFN in first pregnancy?
No, this is the stimulating pregnancy. Only ABO HDFN can occur in first pregnancy but can be mild.
How can ABO HDFN occur in first pregnancy?
O mother giving birth to an A or B child
Which pregnancy can Rh/Non-ABO antibodies cause HDFN?
Only the second pregnancy because IgG antibody can now cross the placenta.
What are symptoms of HDFN?
Anemia, Increased bilirubin leading to kernicterus, Low hemoglobin
What is accumulation of bilirubin in the central nervous system called? What can it lead to? When would this occur?
Kernicterus –> can lead to deafness, mental retardation, death, heart failure. This would occur after birth.
Why does bilirubin increase during HDFN?
Sensitized fetal RBCs are destroyed in the liver causing increase in bilirubin, fetus cannot conjugate bilirubin due to lack of glucuronyl transferase enzyme
What are the “other” types of HDFN? Why?
Anti-K, Anti-Duffy, Anti-Kidd, since these are IgG, able to cross the placenta, and well developed at birth
What type of HDFN can occur in any pregnancy?
ABO (Group O mothers with Group A or B infants)
S&S of infant with ABO HDFN
Elevated ESR
Increased osmotic fragility
Increased spherocytes
Mild to high bilirubin
ABO HDFN DAT
Usually weakly positive or negative
What are some types of prenatal testing before birthing process to assess HDFN?
ABO, Rh, Weak D, Antibody screen, Antibody titrations
How to determine antibody titer?
Last positive result is your titer
1st titer vs 2nd titer for prenatal antibody testing
1st titer is an estimate of maternal antibody concentration
2nd titer is run in parallel with 1st specimen; any change >2 steps is a significant increase
Significant titers
16, 32 or higher
How to test bilirubin in baby
Delta A450 test on Liley Graph
What is the X and Y axis on a Liley Graph?
X axis = Weeks Gestation
Y axis = Delta OD450
What do the zones mean on a Liley Graph? Where are they located?
Zone 1 (bottom third) means the baby is not affected
Zone 2 (middle) means the baby is affected, continue to monitor
Zone 3 (Top third) means the baby has life threatening anemia, consider induction of labor
Percutaneous umbilical blood samples (PUBS) aka? What can it perform?
Cordocentesis; Can perform hemoglobin, hematocrit, bilirubin, reticulocyte, DAT
What are FDA AABB blood requirements for IUT?
Fresh blood <5 days old
CMV negative (leukoreduced)
Hemoglobin S negative
Irradiated
O Neg pRBC and AB FFP
What are 2 ways to perform an IUT?
- Transfuse the fetus directly through abdominal wall into peritoneum
- Intravascular IUT
What 5 criteria is cord blood testing required for? (not all of them needed, just 1 is enough to perform cord bloods on)
- Infants with Rh negative mothers
- Infants from Group O mothers
- Infants in the NICU
- Infants born from mothers with clinically significant antibodies
- Infants born from mothers with no prenatal historu
What tests are done on cord bloods?
ABO, Rh, Weak D on Rh negs, DAT, Elution if DAT is pos
What can cause a false positive with cord blood testing?
Wharton’s Jelly, In vivo sensitization
What is the blocking phenomenon?
All D sites on baby’s D cells are blocked by maternal anti-D causing a false negative (D neg when they are actually D pos)
What is normal cord blood hemoglobin? What value indicates severe anemia?
14-20 g/dL
<8 = severe anemia
What is normal cord bilirubin?
1-3 mg/dL
What is abnormal cord bilirubin? When should a fetal IUT occur? What indicates kernicterus?
Greater than 3.
Fetal IUT should occur if bilirubin is 16 mg/dL.
18-20 mg/dL or more = kernicterus
What is the single most important serological test in the diagnosis of HDFN after birth?
DAT
What can cord hemoglobin help us to determine?
Anemia and red cell destruction
What can cord bilirubin help us to determine?
The need for exchange transfusion (IUT) and presence of kernicterus
Neonatal treatments for HDFN
Phototherapy (UV light)
Exchange Transfusion
IVIG
How to determine the selection of blood for exchange? (ABO)
Always give O blood (unless mom is A and baby is A or mom is B and baby is B, then give type specific)
Always match baby for FFP
How to determine the selection of blood for exchange (Rh)?
If mom and baby are positive, give positive.
If mom and baby are negative, give negative.
If mom is pos and baby is neg, give neg.
If mom is neg and baby is pos: give neg if infant has HDFN due to maternal anti D and give pos if ABO HDFN is suspected or other AB causing HDFN other than anti-D
Standard dose of RhoGAM
300 micrograms intramuscularly