A presentation on Rh incompatibility.

1. Rh Isoimmunization
Dr. Saima Chaudhary

2. Learning objectives
The student should be able to
• Define Rh isoimmunization
• Describe the pathopysiology of it.
• Enumerate fetomaternal risks.
• Discuss the management of non-isoimmunized pregnant lady.
• Tell the dose and time administration of anti. D
immunoglobulins.
• Discuss the management of isoimmunized pregnant lady.

3. Blood group systems
ABO system Rhesus system
Kell
Duffy
Fya

4. Rh Type Determining Antigen
Rh +ve Rh -ve

5. Inheritence of Rh antigens
• Cc, Dd, Ee
• 2 sets of 3 alleles one inherited from each parent
D d
E
Chromosome 1
e
c
C

6. Inheritence of Rh antigens

7. Rh Isoimmunization
• Immunological disorder in Rh –ve mother
carrying Rh +ve baby
• Mother produces antibodies in response to fetal
Rh antigen on RBC
• Antibodies cross placenta and destroy fetal RBCs
• 90 % Rh isoimmunization -- D antigen
• Risk of alloimmunization depends on amount of
bleed

8. Incidence
• Spontaneous
abortion=3.5%
• Induced abortion=5.5%
• Ectopic pregnancy=1%
Incidence of Rh –ve
individuals vary by race
• Asians 1%
• North americans 15%
• Blacks 7-8%

9. Pathophysiology
First pregnancy
Placental barrier
intact

10. Pathophysiology
Primary sensitization
First pregnancy
Placental barrier
broken
Produce IgM
IgM
IgM
IgM

11. Pathophysiology
Second pregnancy
IgG
Same antigen
IIgGIIgGH

12. Hb
Fetal ascites
Pericardial effusion
Hepatospleenomegaly
Heart failure

14. Fetomaternal Risks
Fetus
• Anemia
Enlarged heart
Ascites and pericardial
effusion
Hyperdynamic fetal
circulation (MCA PSV)
Reduced fetal
movements
Abnormal CTG
• Hydrops
Mother
Polyhydramnios.
Neonate
• Pallor ++
• Hepatosplenomegaly
• Jaundice
• Kernicterus
(encephalopathy)

17. All pregnant women
• Blood group and Rh factor
• Antibody screen by indirect coombs test
• Anti-D, Anti-c, Anti-E, and Anti-Kell

18. Rh Nonsensitized Women
Objective of management
• Prevention of Rh isoimmunization
• Detection of Rh isoimmunization

19. Prevention
Anti D immunoglobulin ( RhoGAM)
Mechanism of action:
Anti D
IgG
Ig
production
suppression

20. Prevention
Dose: 300υg(1500IU) = 30ml fetomaternal bleed
Route: I/M
Time: within 72 hours of sensitizing event
1st trimester events: 250 IU
Events between 12 -20 weeks: Minimum 250 IU (+
Kleihauer test)
Events 20 weeks onwards: Minimum 500 IU (+ Kleihauer
test)

21. Timing of Anti- D for Prevention of
Isoimmunization
• Antepartum haemorrhage
• Amniocentesis / CVS / FBS
• External cephalic version
• Trauma
INDICATIONS
• At 28 weeks
• Postpartum within 72 hours
• Spontaneous / induced abortion
• Ectopic pregnancy
• Partial mole
Kleihauer Betke
test
Additional
10μg/1ml Anti D

22. Detection of isoimmunization

23. Mrs. Shehnaz, 30-year-old G2P1
presented at 16 weeks gestation
in OPD to show her reports. Her
blood group was O-ve. Indirect
coomb’s test was negative.
How would you proceed with
further management in this
lady?

24. Nonsensitized Rh –ve Women
Husbands blood group
If Rh –ve
• Indirect coomb’s test
repeated only once 32-
34 weeks
• Anti D injection not
given
If Rh +ve
• Indirect coomb’s test at
28 weeks and 32 weeks
• Anti D Ig given at 28 wk
• Cord blood – blood group
and coomb’s test
• Anti D within 72 hours of
delivery

25. Mrs. Shehnaz, 32-year-old G3P2 presented at 18 weeks
gestation in OPD for antenatal check up. She did not get
Anti D injection in last delivery. Indirect coomb’s test is
positive now. How would you manage this lady?

26. Sensitized Rh –ve Women
Once sensitization– can’t turn back clock
Disease gets worse and at earlier
gestation with successive pregnancies
Objectives
• Close surveillance of antibody titer
• Detection and correction of fetal anemia
• Surveillance of fetal health
• Delivery at optimal time through optimal mode

27. Sensitized Rh –ve Women
• Careful history
• Previous pregnancy losses (Time/ cause)
• h/o blood transfusions
`
Husband’s blood group &
genotype
-ve blood group +ve blood group
Hemolytic disease not
possible
fetal blood group
Free fetal DNA/ amniocytes
Rh +ve
Rh-ve
No measures
required

28. Sensitized Rh –ve Women
Rh +ve husband
• Fetomaternal medicine specialist care
• Antibody titers: Titers as 1: 2, 4, 8, 16, 32, 64
• Antibody levels IU/ml
• Levels better correlate with HDFN
• Frequency: repeated 4 weekly till 24 weeks, 2
weekly afterwards
Antibody level Antibody titer Risk of HDFN
< 4 IU/ml HDFN unlikely
4- 15 IU/ml Moderate
> 15 IU/ml 1:16 1:32 High

30. Detection of Fetal Anemia
MCA Doppler
Peak Systolic
Velocity
MCA PSV 1.5
MoM and above
cordocentesis and
consider IUT
If no facilities for
FBS,
amniocentesis
MCA PSV less
than 1.5 Mom
Monitor MCA PSV
1-2 wkly

31. Normal and Abnormal MCA Dopplers
• Non-invasive
• NO risk for worsening
isoimmunization
• Utility with alloantibodies
other than Rh-D, including
anti-Kell antibodies

33. Antibody titer
> 15 iu/ml
>1:16
MCA PSV
> 1.5 mom
FBS/ hematocrit
<30% Blood
transfusion
Delivery at lung
maturity/ 37-38
weeks
Antibody titer 2-4 weekly
MCA 1-2 weekly
Fetal blood sampling 1-2 weekly
Amniocentesis for OD450 indicated
MCA not available
After 35 weeks (MCA false +ve)

34. Amniocentesis & ΔOD 450
• Amniocentesis and checking
delta OD 450 to check level of
bilirubin in AF
• Plot values on Liley Curve
• Measures the level of bilirubin
and predicts severity of
hemolytic disease after 27
weeks
• Delivery or intrauterine
transfusion if delta OD450 falls
into zone III or upper zone II

35. Liley’s Curve

36. Amniotic Fluid Deltaod 450

37. FBS & Intrauterine Blood
Transfusion
Transfusion Techniques
• Intravascular transfusion
• Intraperitoneal transfusion
Survival rate after intrauterine transfusion
• Hydropic baby=75%
• Non hydropic baby=90%
Tests performed on blood sample
• Blood group
• CBC
• Coomb‘s test
• Retic count
• Bilirubin level

38. Fetal surveillance & Antenatal
Steroids
• Antenatal testing with non stress test &
biophysical profile at 32 weeks
• If preterm delivery <36 wks may be predicted,
then antenatal steroids must be given to enhance
fetal lung maturity
• 2 doses of betamethasone 12 mg 24 hours apart

39. Delivery
Time : not before 36-37 weeks
Settings: Unit with adequate neonatal support
Neonatologists present at delivery
Continuous FHR monitoring
Mode of delivery: decided on Obstetric
grounds
At delivery: Cord blood saved for
• Blood group
• CBC
• Coomb’s test
Blood arranged

40. Neonatal Management
• Commonly need Phototherapy
• Anemia – blood transfusion
• May need Exchange Transfusion
• Haematinics long term
• Bone marrow suppressed
if IUT
• Good long term outcome