Faculty of Allied Medical Science
Blood Banking (MLBB 201)
HEMOLYTIC DISEASE OF
THE NEWBORN
Prof. Dr Nadia A. Sadek
Prof. in Hematology, Head of Blood Bank, MRI
Learning outcome
This lecture will enable the students to:• Recognize HDN, its presentation and
complications
• Know the laboratory tests for its diagnosis
and management.
Hemolytic Disease of the
Newborn
It is a condition in which the life span of the
fetal/neonatal red cells is shortened due to
maternal alloantibodies against red cell
antigens acquired from the father.
• Maternal IgG cross the placenta and bind
to the corresponding antigen on fetal red
cells which are then removed by the fetal
phagocytic system. The most common
antibodies are related to the Rh and ABO
system. The D antigen is highly
immunogenic followed by c, anti K.
• Lewis and P1 antibodies occur frequently
in pregnancy, but being of IgM type they
do not cross the placenta. In addition, the
Lewis antibodies are not fully developed at
birth.
• All women who had previous pregnancies
or blood transfusion may be immunized
against foreign red cell antigens.
• Women without such a history can also be
immunized either because the antibodies
are naturally occurring or because a
spontaneous abortion has passed
unrecognized.
• Blood samples from pregnant females are
tested early for alloantibodies at 12-16
weeks, at the booking visit and at 28-32
weeks for a rising anti-D titre. In case of
anti-K, severe HDN can occur even at low
titres.
• Anti-A,B may occur in group O mothers
delivering an A or B infants, but the
disease is mild and does not need
exchange transfusion.
• The difference between HDN due to ABO
and Rh incompatibilities includes:-
• Low incidence of need to exchange
transfusion in ABO versus Rh antibodies.
• ABO is found in the first and the .
subsequent pregnancies. In Rh the first
pregnancy may be unaffected.
• ABO antigens are expressed by a variety
of fetal and adult tissues reducing the
chances of anti-A binding on the fetal RCs.
• The risk of sensitization to the RhD
antigen is reduced if the fetus is ABO
incompatible. This is because any fetal
cells that leak into the maternal circulation
are rapidly destroyed by potent anti-A and
anti-B thus reducing the likelihood of
maternal exposure to the D antigen.
• In the first sensitization the maternal anti D
is IgM and does not cross the placenta,
while in subsequent pregnancy, it is of IgG
type and crosses the placenta to destroy
the fetal red cells.
Coombs test in HDN
Direct Coombs:• A sample of fetal RBCs is washed to
remove any unbound Ig. The reagent
agglutinates any fetal RBCs to which
maternal antibodies are already bound.
Indirect test:• To prevent HDN. It is carried out on
mother’s serum to find anti-D antibodies.
The serum is incubated with Rh D-positive
cells, washed to remove excess, reagent
is added. If the mother is sensititized
agglutination occurs.
Clinical features
• HDN may manifest as a mild hemolytic
anaemia with slight jaundice on the
second or third days of life and mild
anaemia.
• More severely affected infants have
severe hyperbilirubinaemia (icterus gravis
neonatorum).
• If left untreated, bilirubin reaches the
basal ganglia (kernicterus) and the
condition may be fatal or leads to mental
retardation and spasticity.
• In the most severe cases, profound
anaemia occurs in utero and intrauterine
fetal death may occur.
• The fetus presents with severe anaemia,
oedema and ascites. The placenta is
bulky, swollen and friable, a condition
known as hydrops fetalis which
necessitates ultrasound-guided
intravascular transfusions.
• In hydrops fetalis extravascular hemolysis
stimulates extramedullary haematopoiesis
in the liver with distortion of the hepatic
circulation, portal hypertension, impaired
albumin production resulting in oedema,
pleural and pericardial effusions.
• The severe anemia leads to heart failure
and tissue hypoxia, and fluid extravasation
to the extravascular space.
Blood picture
• The fetal blood film shows polychromasia
and increased numbers of nucleated red
cells (normoblasts).
• The direct antiglobulin test (DAT) on the
infant’s red cells is positive except in some
ABO antibodies.
• In ABO incompatibility the infant’s blood
film shows spherocytosis (not seen in Rh
HDN).
Rh hemolytic disease of the
newborn
• Anti-D accounts for 90% of the cases.
• Maternal antibodies are usually
undetected before 28 weeks.
• The most objective means of quantitating
anti-D levels is by automated analyser,
flow cytometry or manually.
• Following delivery, all RhD-negative
women unsensitized for RhD should be
given prophylactic anti-D immunoglobulin
if the infant is RhD positive.
• The antibody level in maternal blood is
affected by:-
- IgG subclass
- Rate of rise of antibody
- Past history of immunization
- Presence of blocking antibodies.
• Level below 1iu/ml (0.2ug/ml) require no
action, a level of 10iu/ml (20ug/ml)
necessitates amniocentesis.
Antenatal assessment of HD
• Ultrasound-guided fetal blood sampling
from 18-20 weeks of gestation.
• Bile pigments measurements in the
amniotic fluid from week 28 onwards.
• Fetal haemoglobin deficit necessitates
intravascular transfusion of O-negative
blood, CMV-negative and irradiated blood.
• Rh genotyping of amniotic cells by DNA.
Intrauterine transfusions
• Injection of antigen-negative donor red
cells in infant in utero either into the
peritoneal cavity, or directly into fetal
umbilical vessels . In the latter, ascites
should not be present otherwise
absorption of the red cells into the fetal
circulation will be slow.
Management
• Plasma exchange during pregnancy in
cases of high antibody titres in the mother.
• Premature delivery after 34 weeks.
• Exchange transfusion to the newborn.
The compatibility test should be performed
to the mother and newborn against mother
serum.
ABO HDN
• The A and B antigens are not fully
developed in the infant. In A and B
subjects the anti-B and anti-A are IgM and
do not reach the fetus.
• ABO HDN occurs in group O mothers
possessing IgG anti-A, anti-B
HDN due to other antibodies
• Anti-c and anti-K are due to previous
maternal blood transfusions. Anti-K may
cause severe fetal anaemia necessitating
intrauterine or exchange transfusion.
Prevention of HDN
- Routine administration of 500iu of anti-D to
all Rh-negative mothers within 72 hours of
delivery of an Rh-positive infant.
- Detection and quantitation of fetal red cells
in maternal blood sample taken within 1
hour after delivery by Kleinhauer acidelution test.
• All females in childbearing period requiring
blood transfusion should receive cnegative, K-negative blood to prevent
sensitization.
Case presentation
• Accurate Rh testing can be difficult if the
red cells are heavily coated with IgG antiD antibodies; a phenomenon called
“BLOCKED D”
• Rh D negative report was obtained in a
newborn male baby with severe HDN and
features of kernicterus. He was born to a
second gravida B Rh negative mother.
• The baby was grouped as B Rh D
negative by direct grouping, but after
elution, D Ag was detected and he was
phenotyped as CcDe.
• Direct Coombs was strongly positive after
3 exchange transfusions.
• The baby had free antibodies apart from
the red cell bound. The mother had IgM
and IgG anti D as well as anti C and IgG
anti-A.
Prevention of HDN
- Determine the Rh status of the mother
- Indirect Coombs on the mother’s serum to
detect sensitization.
- Give anti D at 28 weeks (time of starting
fetal D antigen expression)
- Give another dose at 34 weeks (risk of
fetomaternal haemorrhage)
- A final dose after the baby is born
• If the father is homozygous for D allele
D/D, the fetus will be D-positive. If he is
D/d, there is 50/50 chance that the fetus is
D-positive.
• Monitor the pregnancy by ultrasound
• A rising anti-D titre denotes active
hemolysis.
Treatment
• If fetal anemia is severe, blood transfusion
in utero.
• After delivery, exchange transfusion with
O- negative blood.
Study Question
• How to diagnose HDN?
Assignments
• Flow Cytometry
‫سيد احمد كمال‬