[10] CHAPTER IV LESSON 2 Flashcards
A. MANAGEMENT OF THE FETUS
- Fetal Ultrasound
- Invasive Monitoring—Cordocentesis and Amniocentesis
- Intrauterine Transfusion
B. MANAGEMENT OF THE INFANT
- Cord Blood Testing
- Exchange Transfusion
- Simple Transfusions
- Phototherapy
- Intravenous Immune Globulin
- Cord Blood Testing
ABO Grouping
RhD Typing
Direct Antiglobulin Test
Elution
PREVENTION
- Selection of RBCs for Females
- Rh Immune Globulin
- Rh Immune Globulin
a. Dose and Administration
b. Maternal Weak D
c. Other considerations
At about (?), the clinical diagnosis of fetal anemia can be made using an ultrasound technique called
16 to 20 weeks’ gestation
fetal middle cerebral artery peak systolic velocity (MCA-PSV)
Readings are typically done every (?) to track the degree of fetal anemia; those that are greater than (?) multiples of the mean (MoM) are sensitive enough to predict significant fetal anemia in which intervention may be needed.
Fetal Ultrasound
2 weeks
1.5
Enhancement of blood flow, the umbilical vein is visualized at the level of the cord insertion into the placenta.
Invasive Monitoring—Cordocentesis and Amniocentesis
A spinal needle is inserted into the umbilical vein, and a sample of the fetal blood is obtained.
Invasive Monitoring—Cordocentesis and Amniocentesis
For risk stratification of fetal anemia, (?) to monitor amniotic fluid bilirubin levels has been replaced with MCA-PSV
Invasive Monitoring—Cordocentesis and Amniocentesis
amniocentesis
In the past, the concentration of (?) was used to estimate the extent of fetal hemolysis.
Invasive Monitoring—Cordocentesis and Amniocentesis
bilirubin pigment in the amniotic fluid
The amniotic fluid is tested by a (?) at 450 nm (the absorbance of bilirubin).
Invasive Monitoring—Cordocentesis and Amniocentesis
spectrophotometric scan optical density (∆OD)
The measurement is plotted on a graph (?) according to gestational age.
Invasive Monitoring—Cordocentesis and Amniocentesis
spectrophotometric scan optical density (∆OD)
Liley Curve Graph
An increasing or unchanging (?) as pregnancy proceeds predicts worsening of the hemolysis.
Invasive Monitoring—Cordocentesis and Amniocentesis
∆OD 450 nm
High values indicate severe and often life-threatening hemolysis (?) and require urgent intervention.
Invasive Monitoring—Cordocentesis and Amniocentesis
fetal hemoglobin less than 8 g/dL
is performed by accessing the fetal umbilical vein (cordocentesis) and injecting donor RBCs directly into the vein
Intrauterine transfusion
The goal is to maintain fetal hemoglobin above 10 g/dL.
Intrauterine Transfusion
Intrauterine Transfusion
Once initiated, the procedure is typically repeated every (?) until delivery to suppress fetal hematopoiesis.
2 to 4 weeks
The initial Intrauterine Transfusion is rarely performed after (?) gestation.
36 weeks’
Intervention in the form of intrauterine transfusion becomes necessary when one or more of the following conditions exists:
a. MCA-PSV indicates anemia (?).
b. [?] is noted on ultrasound examination.
c. Cordocentesis blood sample has hemoglobin level [?].
d. Amniotic fluid [?] results are high and/or increasing.
> 1.5 MoM
Fetal hydrops
less than 10 g/dL
∆OD 450 nm
Selection of RBC products for intrauterine transfusion
a. Group O
b. RhD-negative (or RhDpositive, depending on maternal blood group antibody)
c. Leukocyte reduced
d. Hemoglobin S negative
e. CMV-safe (CMV seronegative or leukocyte reduced)
f. Irradiated
g. Antigen-negative for maternal red blood cell antibody/antibodies
h. Hematocrit level greater than 70%
i. ABO antigens are not fully developed in newborn infants
ABO Grouping
ii. Infants do not have their own isohemagglutinins but may have those of the mother, so reverse grouping cannot be used to confirm the ABO group.
ABO Grouping
i. Rarely, the infant’s RBCs can be heavily antibodybound with (?), causing a false-negative Rh type, or what has been called (?)
RhD Typing
maternal anti-D
blocked Rh
ii. An eluate from these RBCs will reveal (?), and typing of the eluted RBCs will show reaction with (?).
RhD Typing
anti-D
anti-D
i. The most important serologic test for diagnosing HDFN is the [?] with (?).
Direct Antiglobulin Test
anti-IgG reagent
A positive test result indicates that there is antibody coating the infant’s RBCs
Direct Antiglobulin Test
however, the strength of the reaction does not correlate well with the severity of the HDFN.
Direct Antiglobulin Test
i. The preparation of an eluate may be helpful when the cause of HDFN is in question or suspected.
Elution
is the use of whole blood or equivalent to replace the neonate’s circulating blood and simultaneously remove maternal antibodies and bilirubin.
Exchange Transfusion
RBC units less than (?) from collection from the donor are selected to reduce the risk of (?).
Exchange Transfusion
7 to 10 days
hyperkalemia
After a (?) exchange transfusion, approximately (?) of the red blood cells have been replaced and (?) of the bilirubin has been removed.
Exchange Transfusion
two-volume
90%
50%
After the procedure, a platelet count should be performed to monitor for (?).
Exchange Transfusion
iatrogenic thrombocytopenia
The infant may receive small-volume or (?) RBC transfusions to correct anemia anytime from after birth to many weeks later.
Simple Transfusions
“top-off”
Many hospitals will keep (?) dedicated to an infant with HDFN and draw small aliquots from the parent RBC unit over time to decrease donor exposure over multiple transfusion episodes.
Simple Transfusions
1 unit
is used to metabolize the unconjugated bilirubin to isomers that are less lipophilic, less toxic to the brain, and able to be excreted through urine.
Phototherapy at 460 to 490 nm
is used to treat hyperbilirubinemia of the newborn caused by HDFN.
Intravenous immune globulin (IVIG)
competes with the mother’s antibodies for the Fc receptors on the macrophages in the infant’s spleen, reducing the amount of hemolysis.
Intravenous immune globulin (IVIG)
First pregnancy can be affected ABO
Yes
First pregnancy can be affected RhD
Rare
Disease predicted by titers ABO
No
Disease predicted by titers RhD
Yes
Causative antibody IgG ABO
Yes (AntiA,B)
Causative antibody IgG RhD
Yes (AntiD, etc)
Bilirubin level at birth ABO
Normal range
Bilirubin level at birth RhD
Elevated
Intrauterine Transfusion needed ABO
None
Intrauterine Transfusion needed RhD
Sometimes
Anemia at birth ABO
No
Anemia at birth RhD
Yes
Phototherapy beneficial ABO
Yes
Phototherapy beneficial RhD
Yes
Exchange Transfusion Needed ABO
Rare
Exchange Transfusion Needed RhD
Uncommon
In some countries, minor blood group antigens are matched (or provided as (?)) for women of childbearing potential.
Selection of RBCs for Females
negative
For instance, a number of countries use (?) RBC units for women younger than (?).
Selection of RBCs for Females
K-negative
45 to 50 years of age
Other nations provide additional matching for antigens such as (?).
Selection of RBCs for Females
c and E
In a large international review of women with infants with severe HDFN, a transfusion policy of (?) for RBC transfusion did not provide protection from HDFN.
Selection of RBCs for Females
prospective antigen matching
This appears to be driven by the fact that (?) of maternal sensitization that went on to cause severe HDFN was due to previous pregnancy and not transfusion itself.
Selection of RBCs for Females
83%
The mechanism of action is uncertain.
Rh Immune Globulin
Evidence indicates it interferes with B-cell priming to make anti-D, although other modes of action may occur.
Rh Immune Globulin
Administration of corresponding RBC antibody to prevent active immunization induced by the RBC antigen
Rh Immune Globulin
Bind to and inactivate (?) before the mother’s immune system can respond by producing her own (?).
Rh Immune Globulin
fetal Rh antigens
anti-Rh Ab’s
should be given to RhD-negative mothers.
Rh Immune Globulin
The first dose is provided at (?) gestation, as recommended by the American College of Obstetricians and Gynecologists.
Rh Immune Globulin
28 weeks’
Based on experiments conducted many years ago, it is recommended to give [?] within (?) after delivery.
Rh Immune Globulin
72 hours
Even if more than 72 hours have elapsed, [?] should still be given, as it may be effective and is not contraindicated.
Rh Immune Globulin
The mother should be (?), and the infant should be (?).
Rh Immune Globulin
D-negative
D-positive or D-variant
If the type of the infant is unknown (e.g., if the infant is stillborn), [?] should also be administered.
Rh Immune Globulin
- contains sufficient anti-D to protect against 15 mL of packed RBCs or 30 mL of whole blood.
Regular dose vial in the United States
This is equal to 300 µg of the World Health Organization (WHO) reference material.
Regular dose vial in the United States
- contains about 100ug, which appears to be adequate for postpartum prophylaxis.
Regular dose vial in the United Kingdom
- can be used for abortions and ectopic pregnancies before the 12th week of gestation.
Microdose (United States)
are approved for use in the United States.
Intravenous preparations (IV) of RhIG
These products also contain 300 µg in each vial and can be administered either intramuscularly or intravenously.
Intravenous preparations (IV) of RhIG
A maternal sample should be obtained within 1 hour of delivery and screened using a test such as the
rosette technique for massive fetomaternal hemorrhage
If positive, quantitation of the hemorrhage must be done by
Kleihauer-Betke or by flow cytometry assays
is treated with citric acid and then stained with counterstain.
Kleihauer-Betke test
Maternal blood smear
which is resistant to acid and will remain pink.
Kleihauer-Betke test
Fetal cells contain fetal hemoglobin (Hgb F)
will appear as ghosts.
Kleihauer-Betke test
maternal cells
Kleihauer-Betke test
After 2,000 cells are counted, the percentage of fetal cells is determined, and the volume of fetal hemorrhage is calculated using this formula:
Kleihauer-Betke test
Kleihauer-Betke test
Rounding Rules:
a. If calculated dose to the right of the decimal point is [?], then round up to the next whole number and add one vial.
b. If calculated dose to the right of the decimal point is [?], then round down to the next whole number and add one vial.
> /= to 0.5
< 0.5
Because one [?] dose covers [?] of whole blood, the calculated volume of fetomaternal hemorrhage is then divided by [?] to determine the number of required vials of RhIG.
300-µg
30 mL
30
Because the [?] is an estimate, one vial is added to the calculated answer. When needed, the additional vials of RhIG should be administered within [?] of delivery or as soon as possible.
Kleihauer-Betke
72 hours
In certain patients, serologic reagents do not accurately detect the RhD type.
Maternal Weak D
The most common genetic backgrounds that account for this serologic typing problem are called
Maternal Weak D
weak D phenotypes.
Recently, authors have encouraged the use of (?) for patients with a weak D phenotype to provide accurate and actionable results for RhD blood typing and RhIG administration.
Maternal Weak D
RhD genetic testing
Further scientific study is needed to elucidate the clinical significance of different RhD genotypes in various ethnic backgrounds and the risk factors for RhIG failure.
Maternal Weak D
RhIG is of no benefit once a person has been actively immunized and has formed
anti-D
RhIG is not indicated for the mother if the infant is found to be.
Dnegative
The blood type of fetuses in [?] usually cannot be determined; therefore, RhIG should be administered in these circumstances.
abortions, still-births, and ectopic pregnancies
The following women are not candidates for RhIg:
- D negative women who have D negative babies
- D positive women
- D negative women known to be immunized to D
RhIg must be given to D negative women under the following circumstances in which the baby’s D is unknown:
- After amniocentesis
- After miscarriage
- After abortion
- After ectopic pregnancy
- Vaginal bleeding at anytime during the pregnancy
- Cordocentesis
- Chorionic villus sampling
HDFN is prevented, monitored, and treated with the help of tests performed in the laboratory. Understanding the physiology of HDFN is important in choosing the correct tests to perform and detecting [?]. Important points to remember when performing these tests are outlined.
early indicators of hemolytic disease
Fetal red cells, carrying antigens inherited from the father, stimulate the mother to produce
IgG antibodies
destroy fetal red cells.
Maternal IgG antibodies
In utero, this destruction can cause [?], which can result in heart failure and possibly death.
severe anemia
After delivery, red cell destruction continues with the increase of bilirubin, causing [?] and possible damage to the CNS (?).
jaundice
kernicterus
is the most common type of HDFN and occurs most commonly in group O mothers who deliver group A or B babies.
ABO HDFN
is the most severe type of HDFN
HDFN caused by anti-D
it occurs in D-negative women with anti-D who deliver D-positive infants.
HDFN caused by anti-D
can cause HDFN if the child inherits the antigen from the father and the red cell antigen is well developed on the fetal red cells.\
Any IgG antibody
are most frequently reported after anti-D.
Anti-c and anti-K
are performed on the mother before delivery
ABO/D phenotype and antibody screen
D-negative mothers before delivery should receive
prenatal RhIG
can be helpful in deciding when to perform diagnostic and invasive procedures.
Titration of the maternal antibody
can aid in predicting the severity of HDFN.
(?) of the amniotic fluid and use of the [?]
Spectrophotometric analysis
Liley graph
determines whether a D-negative mother should receive postpartum RhIG.
Cord blood testing
RhIG dosage is determined by the [?] performed on the mother.
fetal screen (rosette) and Kleihauer-Betke test
If HDFN is suspected, [?] should be performed; hemoglobin and bilirubin levels should also be closely monitored.
ABO and D phenotype and DAT
Depending on the severity of HDFN, treatment can begin [?].
in utero or after delivery
After delivery, [?] is used to correct anemia, remove sensitized red cells, and reduce levels of maternal antibody and bilirubin.
exchange transfusion
Blood for exchange and intrauterine transfusion should be [?].
less than 7 days old, irradiated, CMV-reduced-risk, hemoglobin S–negative, and negative for the antigen corresponding to the maternal antibody
[?] resuspended in AB plasma are used most often.
Group O, D-negative RBCs
