Hemolytic disease of the fetus and newborn Flashcards
HDFN is also known as
Erythroblastosis fetalis
HDFN
Fetal or newborn red blood cells (RBCs) are
destroyed by maternal immunoglobulin G (IgG)
Hemolytic disease ofthe fetus and newborn
Maternal antibodies
– Cross the placenta
– Sensitize fetal RBCs
– Shorten RBC survival
The genetic reason for hemolytic disease of the fetal newborn
Rh negative woman and Rh positive man conceive a child
and then effects 2nd pregnancy
HDFN may occur when fetal cellls escape into
the maternal circulation as a result of a
fetomaternal hemorrhage
etiology of fetal RBC antigens
that
the mother does not have
stimulate the mother to
produce antibodies
Etiology
Antibodies bind
Antibodies bind to fetal
antigens and cause RBC
destruction in the fetal
liver and spleen
Etiology
Before birth
Indirect bilirubin is conjugated by
Indirect bilirubin is
conjugated by the
maternal liver
Etiology
Before birth
As RBC destruction continues
fetal
erythropoiesis increases
- Erythroblasts are released
(erythroblastosis fetalis) - Edema occurs in the
peritoneal and pleural
cavities (hydrops fetalis)
Etiology
what may result
Cardiac failure may result
After birth
Newborn cannot _______
Unconjugated bilirubin binds to albumin and then to ____________
Permanent brain damage ( __________) may result if ___________ binds to tissues of the central nervous system
AFTER BIRTH
* Newborn cannot
conjugate bilirubin
* Unconjugated bilirubin
binds to albumin and
then to tissues (jaundice)
* Permanent brain damage
(kernicterus) may result if
bilirubin binds to tissues
of the central nervous
system
Overview of HDFN
what is the RBC antibody type
Fetus must possess an __________ that the mother lacks
___________ is inherited from the father
IgG
- RBC antibody must be IgG
- Only IgG crosses the placenta
- Fetus must possess an antigen
that the mother lacks - The gene is inherited from the father
HDFN
Antigen must be
Well developed at birth
Types of HDFN
Rh (D antigen)
ABO
Other antibodies
Rh HDFN
is the most
Severe
Rh HDFN
when are women sensitized
D-negative women are sensitized during
the first pregnancy with a D-positive baby
Rh HDFN
Subsequent __________ are affected
Pregnancies
Rh HDFN
what is positive
DAT
Rh HDFN
symptoms that may occur
Jaundice and or anemia may occur
Rh HDFN
Rh immune globulin
Is given to prevent Rh HDFN
ABO HDFN
Most common type of
HDFN
ABO HDFN
mother has group _____
_______ may be effected
Mothers IgG ________ attaches to babys red cell antigens
- Mother has group O blood; baby has group A or B
blood - First pregnancy may be affected
- Mother’s IgG anti-A,B attaches to baby’s red cell
antigens
ABO HDFN
Production of mild symptoms is possible due to
- A or B substances in tissue that may neutralize
antibodies - Fetal/infant RBCs may be poorly developed
- Fetal/infant RBC sites may be reduced
ABO HDFN
__________ may occur
Jaundice
Phototherapy can be used to treat
Jaundice
Other types of HDFN
-Any IgG can cause HDFN
-Anti-c and anti-K antibodies are
common causes
-Other Kell antibodies and
antibodies to Kidd, Duffy, S, and
-U antigens are less common
-Agglutination with paternal
cells and maternal serum is a
clue to a low-frequency antigen
ANY _______ can cause HDFN
IgG
__________ and _________ antibodies are common causes
Anti-c and anti-K
what are less common causes of HDFN
Kell, Kidd, Duffy, S, and U
what is a clue to a low frequency antigen
Agglutination with paternal cells and. maternal serum
Prenatal testing serves two purposes
– Identifies D-negative women who are candidates for RhIG
– Identifies women with antibodies capable of causing HDFN
Antibody titration helps determine
helps determine whether certain
procedures should be performed
Antibody titration
Baseline titer is determined in the first _________ and repeated at ___________
Baseline titer is determined in the first
trimester and repeated at 4- to 6-week
intervals (sample is frozen for future testing)
Antibody titration
A titer that rises by
2
dilutions (compared to
baseline) is significant
A titer of ___ or ____ s
usually critical for anti-D
and other Rh antibodies
16-32
is
usually critical for anti-D
and other Rh antibodies
The highest concentration of dilution compared with these two numbers
1:2 or 1:128
1:128
Ultrasound
Color doppler ultrasonography can detect
Fetal anemia
Ultrasound
Color Doppler ultrasonography can
detect fetal anemia
leads to
Increased cardiac output and low
blood viscosity
Ultrasound
Severity of anemia is determined by evaluating the peak ___________
systolic velocity
in the middle cerebral artery
Amniocentesis is scanned by
spectrophotometrically for
350 to 700 nm
Amniocentesis
A change in optical density above
baseline (450
nm) is a measure of bilirubin
Aminocentesis
The OD is plotted on a
Liley
graph (using gestational age)
– Upper zone (zone 3): severe
HDFN
– Middle zone (zone 2):
moderate disease
– Lower zone (zone 1): mild
disease
Aminocentesis
Three alternatives exist based on results
– Pregnancy continues to term
– Intrauterine transfusion is performed
– Early labor is induced
* Fetal lung maturity must be determined (lecithin-sphingomyelin
[L:S] ratio should be greater than 2:1)
Cordocentesis
Fetal blood sample is taken for
- Hemoglobin and hematocrit testing
- Bilirubin testing
- RBC genotyping
Cordocentesis
_________ is low
1% to 2%
Cordocentesis
Cordocentesis can be used for
intravascular transfusions in cases
of severe HDFN
Fetal genotyping
- Fetal DNA can be typed using maternal
plasma during the second trimester - Predicting the fetal genotype could avoid
amniocentesis or cordocentesis if the fetus
lacks the antigen
Postpartum testing
D testing
– All infants born to D-negative mothers are tested,
including for weak D antigen
Postpartum testing
False negative results
Preform what
- D-antigen sites are blocked by antibody (blocking
phenomenon) - Perform elution (will demonstrate anti-D antibody)
False positive results
- Weak D test is performed on RBCs coated with antibodies
- Rh control will be positive at antihuman globulin (AHG)
phase
Cord blood or neonate testing
ABO testing
- Only the forward grouping is
performed - ABO antibodies are not yet produced
- Cord blood is washed to remove
Wharton’s jelly
DAT
- Elution may be necessary if the test is
positive and if the mother’s antibody
has not been identified or the
maternal serum sample is unavailable - If the eluate is negative, an antibody
to low-frequency antigen is
suspected - If the eluate is positive with A or B
cells and negative with screening
cells, ABO HDFN is indicated
Prevention
RhIG prevents
alloimmunization in D-negative
mothers
RhIG only prevents
formation of anti-D antibody
Antepartum administration
Intitial dose (300ug) is given at
28 weeks’ gestation
Postpartum administration
- Nonimmunized women receive one full dose of RhIG within 72
hours of delivery - More than one dose may be necessary if the mother has
fetomaternal hemorrhage of more than 30 mL
Rosette Test
Screening for fetomaternal hemorrhage
RhIG candidates are screened for
Fetomaternal hemorrhage
Screening for
Fetomaternal Hemorrhage
Most common screening method is the rosette test
- Uses postpartum maternal specimen
- Maternal RBCs are incubated with anti-D antibody
- D-positive indicator cells are added
- Rosettes are observed under the microscope
- Less than 1 rosette per 3 low-power fields: one dose of RhIG
- More than 1 rosette per 3 low-power fields: bleed must be
quantitated
Quantifying Fetomaternal
Hemorrhage
To calculate the additional doses of RhIG, what is used
flow
cytometry or the Kleihauer-Betke test is performed
Quantifying Fetomaternal
Hemorrhage
Kleihauer-Betke test is based on the following facts
– Fetal hemoglobin is resistant to acid (retains dye)
– Adult hemoglobin is not resistant to acid (ghost-like)
Kleihauer-Betke
Acid Elution
Hemoglobin ____ is resistant to acid elution
Expose thin smear of blood to acid buffer,
F
Expose thin smear of blood to acid buffer adult
hemoglobin eluted out.
Kleihauer-Betke
Acid Elution
- Smears are stained with hematoxylin and erythrosin
B. - Adult rbcs appear as ghost cells, stroma only, while
fetal cells appear bright pink and refractile. - Count number of fetal cells in 2000 adult cells.
- Precision of test poor even in experienced hands.
- Flow Cytometry!
RhIG dosing calculation
Treatment
Intrauterine transfusions
ABO/Rh and DAT results should be interpreted with
caution in newborns who
have had intrauterine transfusions
Treatment
Intrauterine transfusions
_________ may phenotype as group O, D negative blood because group O, D-negative unit is given
Cord blood
Intrauterine Transfusions
DAT may be
Falsely negative or weakly positive
Intrauterine Transfusion
Corrects
anemia and prevents heart failure
Intrauterine transfusion
Blood for intrauterine transfusion
Lacks what
RBCs collected within
Group O Rh neg RBCs
Lack
antigens
which
antibo-
dy(ies) are
directed
within 7 days
Blood for intrauterine transfusions
__________ to prevent graft- versus host disease
Irradiated
blood to Intrauterine transfusions
Negative for
Cytomegalo-
virus and/or
leukocyte
reduced
Blood for intrauterine transfusion
Negative for Hgb ____
Negative for Hgb S
Exchange transfusion
Replacement of
1-2 whole blood volume
Exchange transfusion
Corrects anemia without expanding the _________
Removes newborns RBC and replaces with _________
Reduces what
- Corrects anemia without expanding the blood volume
- Removes newborn’s RBCs and replaces them with
antigen-negative cells - Reduces bilirubin (prevents kernicterus)
- Reduces maternal antibody
Exchange
Transfusion
_________ is determined in a infant
ABO and D
Exchange Transfusion
Maternal or Infant serum or plasma is.used for
Antigen negative units are given if
what is determined in the infant
- ABO and D
typing is
determined in
the infant - Maternal or
infant serum or
plasma is used
for antibody
screening - Antigen-negative
units are given if
antibody is
present
Exchange
Transfusion
Procedure
- Cannulate umbilical vein.
- “Pull” baby blood.
- Wait
- “Push” donor blood.
- Wait
- Repeat
Phototherapy
Initial treatment for
hyperbilirubinemia
Phototherapy
Mild cases of
HDFN, such as ABO HDFN
Phototherapy
Uses fluorescent
blue light (420 to
475 nm)
Phototherapy
light converts bilirubin to
Light converts bilirubin to isomers
that are excreted in the bile
Phototherapy
If patient is unresponsive
exchange
transfusion may be necessary
