Understanding Rh Immunization and Blood Group Incompatibility

 
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ABO group (O, A, B, AB).
 
Rhesus system (C, D, E antigens).
 
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About 
20% 
of all infants have an ABO maternal
blood group incompatibility
 but only 
5% 
are clinically affected. 
Because
antibodies are (IgM)( cannot cross the placenta and
therefore cannot gain access to fetal erythrocytes)
Hemolytic disease of the newborn (HDN) due to
ABO incompatibility
less severe than Rhesus incompatibility.
 
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This system includes five red cell
proteins or antigens: c, C, D, e, and E. No
“d” antigen.
The 
presence
 or 
absence 
of D antigen
site determines whether an individual is
Rh positive 
or 
Rh negative.
The incidence of Rh-negative genotype
is 15% in  UK
 
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1.
Rh-positive red cells of the fetus enter into the
maternal circulation
2.
the first immune response in the mother is the
formation of IgM antibodies (they do not cross the
placenta) and therefore the first baby is usually
unaffected.
3.
Subsequent antigen exposure leads to an increased
response and IgG formation in the mother, which does
cross the placenta and destroy the fetal red blood cells
(RBC) leading to reticulocytosis, anemia, heart failure
and hydrops.
 
 
fetomaternal hemorrhage occurs late in pregnancy
or during delivery and antibody response slowly
(over 2–6 months)
The initial maternal immunoglobulin M (IgM)
antibody are formed, which do not cross the
placenta.(molecular weight that is too large to
cross the placenta)
 
1.
Hydrops fetalis.
2.
Intrauterine fetal death or early neonatal death
due to cardiac failure.
3.
Icterus gravis neonatorum.
4.
Congenital anemia of the newborn.
 
During pregnancy
routine antenatal prophylaxis with
anti-D
 
: All women who are RhD –ve
are offered anti-D prophylaxis 500 iu
at 28 and 34 weeks regardless of
sensitizing events or previous
administration of anti-D.
 
 
After the potentially sensitizing event 
a
dose, anti-D Ig should be given as soon as
possible but always within 72 hours.
If it is not given it can be taken within 10–28
days may provide some protection.
if <20 weeks, 250 IU of anti-D given IM
 if >20 weeks, 500 IU of anti-D given IM
A Kleihauer test should be performed.
Further anti-D can be given if indicated by
this test.
 
 
the Kleihauer–Betke test
:
it is 
 screening test
 should be performed 
within 2 hours 
of delivery to
identify the amount of fetal–maternal hemorrhage.
Fetal erythrocyte contain Hb F which is more resistant
to acidic solution (citric acid phosphate buffer) or
alcohol denaturation than adult Hb A, so after
exposure to acid only fetal cells remain, The acid is
able to elute adult hemoglobin, but not fetal
hemoglobin, from the red blood cells. As a result, on
subsequent staining the fetal cells appear rose pink in
color, while adult red blood cells appear as “ghosts.
Should be performed before administration of anti-D
 
Direct Coombs’ test:
This test aims at detecting the maternal
antibodies that may be bound to the
surface of fetal RBCs and is performed
after baby’s birth.
Washed infant’s RBCs are incubated with
the 
Coombs’ serum (antiglobulin
antibodies)
. If agglutination is produced,
the direct Coombs’ test is positive. This is
indicative of the presence of antibodies on
the surface of RBCs
 
 
 
1.
The infant is Rh positive.
2.
The direct Coombs’ test on
umbilical cord blood is 
negative.
This test reveals (whether or not)
irregular antibodies cover the
infant’s red cells.
3.
The fetal blood group Rh- positive
 
A 
second dose of 500 IU anti-D
immune globulin should be
administered within 72 h of delivery
She may be given up to 10–28 days
after delivery to avoid sensitization.
This amount is capable of
neutralizing the antigenic potential
of up to 30 ml of fetal blood (about
15 ml of fetal cells)
 
It is routinely administered as Intramuscular
injections, best given into the deltoid muscle,
(injections into the gluteal region often only
reach the subcutaneous tissues and
absorption may be delayed).
A Kleihauer test should be performed. Further
anti-D can be given if indicated by this test.
 
Why are not all the babies born following
Rh incompatibility affected?
1.
The particular woman may be immunologic non
responder.
2.
There may be associated ABO incompatibility.
3.
Less volume of fetal blood entering into the
maternal circulation. Minimal volume required is
0.1 mL.
4.
Fetal response to maternal antibodies varies on
fetal sex. Rh-D positive male fetuses run the higher
risk of severe hemolysis and death, compared to a
female fetus
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1.
failure to administer anti-D
2.
administration of inadequate doses
3.
late administration
4.
Silent fetomaternal hemorrhages.
 
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1.
Husband blood group
2.
in primigravida : previous history of blood
transfusion
3.
In a parous woman: a detailed obstetric history.
4.
 History of fetal affection in the form of stillbirth
or neonatal death due to severe jaundice
following one or two uneventful births is quite
suggestive.
5.
Previous history of hydrops fetalis
6.
History of receiving anti-D immunoglobulin in
previous pregnancies
7.
Current pregnancy sensitizing events
 
 
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No specific finding is observed on general or systemic
physical examination
 
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Blood group and Rh of the husband
:
If Negative
: No further testing as the baby will
be also Rh –ve and the pregnancy will be
managed as normal.
If positive
: consult with a blood bank pathologist
to determine the paternal genotyping
(homozygous or heterozygous)
→ homozygous of Rh antigen → fetus is likely to
be affected 100
→ heterozygous of Rh antigen → fetus is
affected only in 50% cases.
 
 
Cell-free fetal DNA
:
Non-invasive prenatal determination of
fetal Rh D , from maternal blood samples
one
 at 14 weeks
using a conventional PCR for Y
chromosome
,
 
it can be used to prevent
unnecessary prophylaxis.
if an antigen-negative fetus is found,
no further testing is warranted.
 
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the maternal serum is incubated with
Rh-positive erythrocytes and Coomb’s
serum (antiglobulin antibodies).
The red cells will agglutinate if Rh
antibodies are present in the
maternal plasma.
 
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according to Maternal indirect coomb's
test if:
Rh-negative 
unsensitized pregnant
woman(
indirect coomb’s test negative)
Rh-negative 
sensitized pregnant
woman(
indirect coomb’s test positive)
 
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The goal during pregnancy is to keep her
from becoming sensitized.
 Follow up by indirect coomb’s test   at
booking visit if it negative repeat at 20, 24,
and 28 weeks.
 
 
Give routine antenatal prophylaxis
with anti-D immune globulin at 28
weeks (confirm that the patient
indirect coomb’s test negative prior to
treatment).
the pregnancy should not be allowed
to pass the expected date
 
Care during delivery to minimize the
risk of fetomaternal hemorrhage
During labor
1.
Not to give prophylactic ergometrine
during second stage of labor.
2.
Gentle handling of the uterus during
the third stage.
3.
If the manual removal of the placenta
is required, it should be performed
gently
 
 
During cesarean delivery
1.
To avoid blood spillage into the
peritoneal cavity.
2.
To avoid routine manual removal
of the placenta.
3.
Early cord clamping.
 
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Postnatal prophylaxis: it given (within
72 hours). (Though can be given up to 10-
28 days)
 Check for “excessive” fetomaternal
hemorrhage and treat with additional
doses of Rh immune globulin if exposure
is greater than 30 mL of fetal Rh-positive
blood.
 
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1.
Indirect Coombs’ test (ICT) positive at any ANC visit.
2.
estimation of ( Anti-D antibody) titer
repeat it monthly if stable result
every 2 weeks( from 28 weeks until delivery or when
there is rising titer)
The titer < 1:16, expectant management until 38 weeks.
if it becomes ≥1:16, investigate for  fetal anemia every
week by MCA Doppler at 1-2 week interval
 
 
Referral to a fetal medicine specialist should
occur  for an intensive neonatal care unit,
arrangements for exchange transfusion and
an expert neonatologist
when there are :
rising antibody levels/titres above a specific
threshold
or ultrasound features suggestive of fetal
anemia.
 
Doppler study:Middle cerebral artery
(MCA)-peak systolic velocity (PSV) is the
mainstay to assess fetal anemia.
Begin serial MCA Doppler assessments
at 
18 weeks
 of gestation
Repeat Middle cerebral artery (MCA)-
peak systolic velocity (PSV) at 1- to 2-
week interval
 
 
If MCA-PSV
: 
≤1.5 MoM for gestational
age
, 
follow the same protocol for
antenatal monitoring and delivery,
Evaluated every 2 weeks from at least 32
weeks until delivery for fetal well-being
(nonstress tests, modified biophysical
profile ,Doppler assessment)
 
 
A value >1.5 multiples of the
median (MOMs)
 
for gestational age
:
predicts moderate to severe fetal
anemia .indication for( cordocentesis
and intrauterine  fetal transfusion for
a fetal hematocrit of less than 30%.
 
 
 
Serial ultrasonography may detect fetal hydrops
Serial ultrasonography may detect fetal hydrops
and anemia. The important features are:
and anemia. The important features are:
1.
Polyhydramnios
2.
 increased placental thickness (greater than 4
cm)
3.
 pericardial or pleural effusion
4.
Ascites
5.
echogenic bowel
6.
dilatation of cardiac chambers
7.
enlargement of spleen and liver umbilical vein
dilation and fetal edema (hydrops)
 
Cardiotocography
:
 Sinusoidal trace and
decelerative pattern in an affected fetus.
Amniocentesis:
 it is invasive and
increases the risk of sensitization
.by
using The spectrophotometry ;In
presence of bilirubin there is a
“deviation bulge” at Δ OD450 is plotted
in Liley’s chart and accordingly the
management is decided
 
 
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Indication: 
Elevated peak systolic MCA Doppler
velocities (>1.5 MOM).
Benefits:
to detect
fetal blood grouping, Rh type
hematocrit (accurate Assessment of fetal anemia)
direct Coombs’ test
reticulocyte count
total bilirubin level
Fetal hematocrit value <15% is associated with
hydrops
 
Fetal blood transfusion
 is lifesaving in a
severely anemic fetus (hematocrit <30%,
Hb<10 gm/dL) that is too premature . the
aim is to restore hemoglobin levels
preventing hydrops or death. It can be
started at 18 weeks and repeated at
intervals of 1–3 weeks up to 32–34 weeks.it
performed only in fetal medicine units
 
 
 
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Intravascular route.
into the umbilical vein
into the intrahepatic vein
Into the fetal heart.
Intraperitoneal :into the peritoneal
cavity (less used)
 
 
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1.
Rh negative, whole blood with the same blood
Rh negative, whole blood with the same blood
group to that of the baby or with group ‘O’.
group to that of the baby or with group ‘O’.
2.
Relatively fresh- less than 5 days old.
Relatively fresh- less than 5 days old.
3.
Cross-matched with a maternal sample.
Cross-matched with a maternal sample.
4.
Densely packed (Hb usually around 30g/L) so
Densely packed (Hb usually around 30g/L) so
that small volumes are used.
that small volumes are used.
5.
White cell depleted and irradiated.
White cell depleted and irradiated.
6.
Screened for infection including CMV.
Screened for infection including CMV.
7.
The amount is about 160 ml/kg body weight of
The amount is about 160 ml/kg body weight of
the baby
the baby
 
 
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This is the most serious form of Rh
hemolytic disease (HDFN). Of all cases
of fetal hydrops:
90% are due to a non‐immune cause
10% have an immune etiology.
 
 
 
Causes of Nonimmune
Hydrops Fetalis (NIHF)
and Associated Clinical
Conditions
 
 
 
 
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Rh immunization and blood group incompatibility can lead to serious complications in fetuses and newborns. The ABO and Rhesus systems play crucial roles in determining blood group compatibility. Rh-positive red cells of the fetus entering the maternal circulation can trigger immune responses, leading to hemolytic disease of the newborn. Complications such as Hydrops fetalis and intrauterine fetal...


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  1. Rh Rh iso iso- -immunization immunization .

  2. Blood group is defined in Blood group is defined in 2 2 ways: ways: ABO group (O, A, B, AB). Rhesus system (C, D, E antigens).

  3. ABO group ( ABO group (O, O, A, A, B, B, AB). AB). About 20% of all infants have an ABO maternal blood group incompatibility but only 5% are clinically affected. Because antibodies are (IgM)( cannot cross the placenta and therefore cannot gain access to fetal erythrocytes) Hemolytic disease of the newborn (HDN) due to ABO incompatibility less severe than Rhesus incompatibility.

  4. Rhesus system ( Rhesus system (C, C, D, D, E antigens). E antigens). This system includes five red cell proteins or antigens: c, C, D, e, and E. No d antigen. The presence or absence of D antigen site determines whether an individual is Rh positive or Rh negative. The incidence of Rh-negative genotype is 15% in UK

  5. Pathology of rhesus Pathology of rhesus isoimmunization isoimmunization 1. Rh-positive red cells of the fetus enter into the maternal circulation 2. the first immune response in the mother is the formation of IgM antibodies (they do not cross the placenta) and therefore the first baby is usually unaffected. 3. Subsequent antigen exposure leads to an increased response and IgG formation in the mother, which does cross the placenta and destroy the fetal red blood cells (RBC) leading to reticulocytosis, anemia, heart failure and hydrops.

  6. The first child is generally not The first child is generally not affected because: affected because: fetomaternal hemorrhage occurs late in pregnancy or during delivery and antibody response slowly (over 2 6 months) The initial maternal immunoglobulin M (IgM) antibody are formed, which do not cross the placenta.(molecular weight that is too large to cross the placenta)

  7. What are the fetal and neonatal What are the fetal and neonatal complications that may occur when complications that may occur when mother is immunized? mother is immunized? 1. Hydrops fetalis. 2. Intrauterine fetal death or early neonatal death due to cardiac failure. 3. Icterus gravis neonatorum. 4. Congenital anemia of the newborn.

  8. Prevention of rhesus Prevention of rhesus iso immunization: immunization: During pregnancy routine antenatal prophylaxis with anti-D : All women who are RhD ve are offered anti-D prophylaxis 500 iu at 28 and 34 weeks regardless of sensitizing events or previous administration of anti-D. iso- -

  9. After the potentially sensitizing event a dose, anti-D Ig should be given as soon as possible but always within 72 hours. If it is not given it can be taken within 10 28 days may provide some protection. if <20 weeks, 250 IU of anti-D given IM if >20 weeks, 500 IU of anti-D given IM A Kleihauer test should be performed. Further anti-D can be given if indicated by this test.

  10. the KleihauerBetke test: it is screening test should be performed within 2 hours of delivery to identify the amount of fetal maternal hemorrhage. Fetal erythrocyte contain Hb F which is more resistant to acidic solution (citric acid phosphate buffer) or alcohol denaturation than adult Hb A, so after exposure to acid only fetal cells remain, The acid is able to elute adult hemoglobin, but not fetal hemoglobin, from the red blood cells. As a result, on subsequent staining the fetal cells appear rose pink in color, while adult red blood cells appear as ghosts. Should be performed before administration of anti-D

  11. This test aims at detecting the maternal antibodies that may be bound to the surface of fetal RBCs and is performed after baby s birth. Washed infant s RBCs are incubated with the Coombs serum (antiglobulin antibodies). If agglutination is produced, the direct Coombs test is positive. This is indicative of the presence of antibodies on the surface of RBCs

  12. Indication for administration of anti Indication for administration of anti- -D D immunoglobulin immunoglobulin ( (sensitization events sensitization events causing fetal causing fetal- -maternal hemorrhage): maternal hemorrhage): First trimester 1. spontaneous abortions 2. induced abortions (medical Termination of pregnancy) 3. ectopic pregnancy 4. Molar pregnancy 5. Threatened abortion: (only if the bleeding repeated, heavy or associated with abdominal pain).

  13. Invasive prenatal testing ( amniocentesis, chorion villus biopsy& cordocentesis ) Antepartum haemohage( APH): Bleeding associated with placenta Previa or abruption Intrauterine fetal demise Antepartum trauma :Blunt trauma to the abdomen (includes motor vehicle accidents) Manual placental extraction External cephalic version Administration of Rh-positive blood components to Rh-ve female.

  14. Postnatal prophylaxis: Postnatal prophylaxis: immediately after delivery if immediately after delivery if 1. The infant is Rh positive. 2. The direct Coombs test on umbilical cord blood is negative. This test reveals (whether or not) irregular antibodies cover the infant s red cells. 3. The fetal blood group Rh- positive

  15. A second dose of 500 IU anti-D immune globulin should be administered within 72 h of delivery She may be given up to 10 28 days after delivery to avoid sensitization. This amount is capable of neutralizing the antigenic potential of up to 30 ml of fetal blood (about 15 ml of fetal cells)

  16. It is routinely administered as Intramuscular injections, best given into the deltoid muscle, (injections into the gluteal region often only reach the subcutaneous tissues and absorption may be delayed). A Kleihauer test should be performed. Further anti-D can be given if indicated by this test.

  17. Why are not all the babies born following Rh incompatibility affected? 1. The particular woman may be immunologic non responder. 2. There may be associated ABO incompatibility. 3. Less volume of fetal blood entering into the maternal circulation. Minimal volume required is 0.1 mL. 4. Fetal response to maternal antibodies varies on fetal sex. Rh-D positive male fetuses run the higher risk of severe hemolysis and death, compared to a female fetus

  18. Why there are still many cases of Why there are still many cases of isoimmunisation isoimmunisation occurring during pregnancy, pregnancy, Despite Anti Despite Anti- -D prophylaxis?? occurring during D prophylaxis?? 1. failure to administer anti-D 2. administration of inadequate doses 3. late administration 4. Silent fetomaternal hemorrhages.

  19. Management of patient Management of patient found to be Rh found to be Rh- - negative negative

  20. Full history: Full history: 1. Husband blood group 2. in primigravida : previous history of blood transfusion 3. In a parous woman: a detailed obstetric history. 4. History of fetal affection in the form of stillbirth or neonatal death due to severe jaundice following one or two uneventful births is quite suggestive. 5. Previous history of hydrops fetalis 6. History of receiving anti-D immunoglobulin in previous pregnancies 7. Current pregnancy sensitizing events

  21. Examination: Examination: No specific finding is observed on general or systemic physical examination

  22. Investigations: Investigations: Blood group and Rh of the husband: If Negative: No further testing as the baby will be also Rh ve and the pregnancy will be managed as normal. If positive: consult with a blood bank pathologist to determine the paternal genotyping (homozygous or heterozygous) homozygous of Rh antigen fetus is likely to be affected 100 heterozygous of Rh antigen fetus is affected only in 50% cases.

  23. Cell-free fetal DNA: Non-invasive prenatal determination of fetal Rh D , from maternal blood samples one at 14 weeks using a conventional PCR for Y chromosome,it can be used to prevent unnecessary prophylaxis. if an antigen-negative fetus is found, no further testing is warranted.

  24. Indirect Indirect coomb's antibody titer : antibody titer : coomb's test or Rh test or Rh the maternal serum is incubated with Rh-positive erythrocytes and Coomb s serum (antiglobulin antibodies). The red cells will agglutinate if Rh antibodies are present in the maternal plasma.

  25. Management Management according to Maternal indirect coomb's test if: Rh-negative unsensitized pregnant woman(indirect coomb s test negative) Rh-negative sensitized pregnant woman(indirect coomb s test positive)

  26. Group Group 1 1: : Management of the Rh Management of the Rh- - negative, negative, unsensitized pregnant unsensitized pregnant woman( woman(coomb coomb s s test negative) The goal during pregnancy is to keep her from becoming sensitized. Follow up by indirect coomb s test at booking visit if it negative repeat at 20, 24, and 28 weeks. test negative)

  27. Give routine antenatal prophylaxis with anti-D immune globulin at 28 weeks (confirm that the patient indirect coomb s test negative prior to treatment). the pregnancy should not be allowed to pass the expected date

  28. Care during delivery to minimize the risk of fetomaternal hemorrhage During labor 1. Not to give prophylactic ergometrine during second stage of labor. 2. Gentle handling of the uterus during the third stage. 3. If the manual removal of the placenta is required, it should be performed gently

  29. During cesarean delivery 1. To avoid blood spillage into the peritoneal cavity. 2. To avoid routine manual removal of the placenta. 3. Early cord clamping.

  30. After delivery After delivery Postnatal prophylaxis: it given (within 72 hours). (Though can be given up to 10- 28 days) Check for excessive fetomaternal hemorrhage and treat with additional doses of Rh immune globulin if exposure is greater than 30 mL of fetal Rh-positive blood.

  31. Group Group 2 2: : Management of the Rh Management of the Rh- - negative, negative, sensitized pregnant woman sensitized pregnant woman 1. Indirect Coombs test (ICT) positive at any ANC visit. 2. estimation of ( Anti-D antibody) titer repeat it monthly if stable result every 2 weeks( from 28 weeks until delivery or when there is rising titer) The titer < 1:16, expectant management until 38 weeks. if it becomes 1:16, investigate for fetal anemia every week by MCA Doppler at 1-2 week interval

  32. Referral to a fetal medicine specialist should occur for an intensive neonatal care unit, arrangements for exchange transfusion and an expert neonatologist when there are : rising antibody levels/titres above a specific threshold or ultrasound features suggestive of fetal anemia.

  33. Doppler study:Middle cerebral artery (MCA)-peak systolic velocity (PSV) is the mainstay to assess fetal anemia. Begin serial MCA Doppler assessments at 18 weeks of gestation Repeat Middle cerebral artery (MCA)- peak systolic velocity (PSV) at 1- to 2- week interval

  34. If MCA-PSV: 1.5 MoM for gestational age, follow the same protocol for antenatal monitoring and delivery, Evaluated every 2 weeks from at least 32 weeks until delivery for fetal well-being (nonstress tests, modified biophysical profile ,Doppler assessment)

  35. A value >1.5 multiples of the median (MOMs)for gestational age: predicts moderate to severe fetal anemia .indication for( cordocentesis and intrauterine fetal transfusion for a fetal hematocrit of less than 30%.

  36. Serial ultrasonography may detect fetal hydrops and anemia. The important features are: 1. Polyhydramnios 2. increased placental thickness (greater than 4 cm) 3. pericardial or pleural effusion 4. Ascites 5. echogenic bowel 6. dilatation of cardiac chambers 7. enlargement of spleen and liver umbilical vein dilation and fetal edema (hydrops)

  37. Cardiotocography: Sinusoidal trace and decelerative pattern in an affected fetus. Amniocentesis: increases the risk of sensitization.by using The spectrophotometry presence of bilirubin there is a deviation bulge at OD450 is plotted in Liley s chart and accordingly the management is decided it is invasive and ;In

  38. Ultrasound guided cordocentesis: Indication: Elevated peak systolic MCA Doppler velocities (>1.5 MOM). Benefits:to detect fetal blood grouping, Rh type hematocrit (accurate Assessment of fetal anemia) direct Coombs test reticulocyte count total bilirubin level Fetal hematocrit value <15% is associated with hydrops

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