Rh isoimmunization occurs when an Rh-negative mother carries an Rh-positive fetus. During pregnancy or delivery, fetal red blood cells can enter the mother's circulation, stimulating her immune system to produce antibodies against the Rh antigen. These antibodies can then cross the placenta during subsequent pregnancies and destroy fetal red blood cells, causing hemolytic disease of the newborn. Effects range from mild anemia to severe jaundice, hydrops fetalis, or fetal death. Management involves monitoring maternal antibody levels and fetal well-being through amniocentesis and ultrasound. At-risk pregnancies may require intrauterine transfusions or early delivery. Prevention relies on administering Rh immunoglobulin to the mother during

1. Rh-ISOIMMUNIZATION IN PREGNANCY

2. Rh Isoimmunization

3. Introduction
•Isoimmunization:
Production of antibodies in response to an antigen derived
from another individual of the same species
•Rh isoimmunization:
Maternal antibody production in response to fetal red blood cell
Rh antigen,when mother Rh-ve ,fetus Rh+ve.

4. Introduction of ABO blood group system
• Four blood types(A, B, AB & O)
• Each blood type is additionally classified according to the
presence or absence of Rh factor

5. Rh alleles: Cc, Dd and Ee. D antigen, the most potent, its presence
or absence denotes an individual to be Rh +ve or –ve. DD-
homozygous, Dd-heterozygous, dd- negative.

6. Pathophysiology
• 1st Rh+ve pregnancy:Rh negative mother bearing Rh positive fetus
• Feto-maternal bleed:
 Abortion(Spontaneous 3-4%, Induced 5%)
 Amniocentesis, CVS, Cordocentesis
 Antepartum hemorrhage
 Abdominal trauma
 Ectopic pregnancy
 External cephalic version
 Third stage of labor
 Cesarean section

9. • Incidence of Iso-immunization is only 2-16% because of
following factors:
ABO incompatibility: confers protection against RH antigen
Critical sensitizing volume: 0.1 ml
Inadequate placental transfer of immunoglobulins
Rh-stimulus non-responders
Difference in immunogenicity of antigen

10. EFFECTS ON FETUS
There is no risk 1st trimester abortion in RH isoimmunization
unless a/w other congenital anomalies
Effects of RH isoimmunization is not evident till second
trimester of pregnancy
only after 2nd trimester the reticuloendothelial system of fetus is
developed and RH antigens are formed in utero

11. 1.CONGENITAL ANEMIA OF NEWBORN:
mildest form( Hb: 12 g/dl)
About 50%
extramedullary hematopoiesis leading to liver and spleen enlargement
2.ICTERUS GRAVIS NEONATORUM:
moderate(Hb:7-12 g/dl)
about 25-30%
unconjugated hyperbilirubinemia
critical level of 20mg/100ml bilirubin: kernicterus
Features: loss of moros reflex,
posturing, poor feeding
bulging anterior fontanelle
high pitched cry,seizures

12. HYDROPS FETALIS

14. Effects on mother
Rh isoimmunization is suspected in utero when mother develops:
1.Polyhydraminos
2.Pre eclampsia
3.Maternal syndrome: generalized edema, proteinuria, pruritus due to
cholestasis
Other complications:
4.Post partum hemorrhage: big plaenta and blood coagulopathy
5.DIC: retention of dead fetus in utero

15. Management of Rh isoimmunisation
Prenatal Diagnosis
1. Maternal:
• History: Previous episodes of possible sensitization (Causes of feto-
maternal bleed and prior Rh+ baby)
• ABO and Rh Blood groups of mother and father

16. • Antibody screening: Indirect Coomb’s test
If +ve: test serially for high titers of maternal anti-Rh IgG
(Critical level: >1:16)
If antibody titre +ve, then repeat monthly- sudden rise is
significant
If –ve at 12th week:
1.Primigravida: Repeat at 28th and 36th week
2.Multigravida: Repeat at monthly intervals from
24th week onwards

17. 2.Fetal
• Serial Amniocentesis: for estimation of bilirubin in amniotic fluid
A.Indications of amniocentesis
i.High antibody titre(>1:8)
ii.Previous severely affected baby
B.Time
i. No history of previously affected baby:30-32 weeks then repeat after
3-4weeks
ii. Previously affected baby:>10 weeks prior
C. Analysis: Spectrophotometry of bilirubin contained amniotic fluid is done
and plotting is done and optical density of the fluid at wavelength 450 nm is
plotted in Liley’s chart. The deviation bulge obtained is directly proprtion to
the severity

19. • Ultrasonography
Polyhydraminos
Fetal hepatosplenomegaly, Bowel wall edema (Extramedullary
hematopoiesis)
Cardiomegaly, pericardial effusion
Scalp and limb edema
Abnormal fetal posture (Buddha position)
Sluggish fetal movement
Placental hypertrophy and thickening

20. • Middle Cerebral Artery Peak Systolic velocity(most accurate)

22. • Cordocentesis(PUBS)

23. Treatment
• Unimmunised mother: expectant till term, but not to exceed
the expected date of delivery
• Immunised mother: terminate pregnancy after maturity if
evidence of hemolysis, previous history of still birth, sudden
rise in antibody titre, or guided by optical density 450 in
Liley’s chart or MCA systolic velocity or fetal Hematocrit

24. Zone I: continue till term, baby unlikely to
be affected
Zone II: may require premature
termination beyond 34 wks
Zone III: severely affected baby.
Imminent fetal death. Termination if >34
wks. If <34wks intrauterine transfusion
repeatedly till 34 wks then terminate.

25. Cordocentesis MCA Peak Systolic velocity
IUT

26. • Care during delivery
Vaginal delivery: Careful fetal monitoring,
Gentle handling of uterus in 3rd stage of labor
No prophylactic ergometrine
Cesarean Section: Avoid blood spillage into peritoneal cavity and
Manual removal of placenta
Clamping umbilical cord: Quickly done and cord kept long (15-
20cm) for exchange transfusion if needed
Collection of cord blood for investigations: ABO and Rh blood
group, Hb, Bilirubin, Direct Coomb’s test

27. • Intrauterine transfusion:
for severely affected fetus before 34
wks.
 Can be started at 18 wks, repeat at 1-
3 wks interval upto 30-32 wks then
terminate pregnancy.
O-ve packed cells compatible with
mother and fetus given by
intraperitoneal or intravascular
approach.

28. Prevention of Rh isoimmunisation
• Administration of Rh anti-D immunoglobulin to mother
Dose- 300µg IM following delivery, 100µg IM following
abortion,amniocentesis, ectopic preg, mole, APH etc.
At 28 weeks to Rh-ve mother if:
a. Father is Rh+ve or father’s Rh status unknown
b. Prior history of causes suggesting feto-maternal bleed
Postpartum (within 72 hrs) if: Rh+ve fetus & DCT –ve
After abortion
• If mother has been sensitized previously, administration of Rh IgG is of
no value.

29. • 100µg neutralise 5 ml RBC.
• The no of fetal RBCs in maternal circulation
is determined by
Kleihauer-Betke(KB) test.
• The dose of anti-D IgG is based on the
result of KB test.

30. Thank You