this presentation is from the point of view of UG teaching

1. RHESUS NEGATIVE PREGNANCY
Dr Nilam Dixit

2. Rhesus factor?
• It is a Red blood cell antigen
• Other Red cell antigens include -
• A, B – blood groups
• Duffy, Kell, Kidd

3. Genetics of Rh factor
• C, D and E antigens
• D antigen is the most
important and determines Rh
positivity
• cDe is Rh positive
• Two alleles – heterozygotes or
homozygotes
• Rh negative person has dd
genotype

4. Pathophysiology in pregnancy
• Rh negative mother
• Carrying a Rh positive fetus
• Some Rh positive RBCs cross
over into the maternal
circulation
• Since the mother has not been
exposed to these antigens,
• She makes antibodies to this
“D” antigen
• Critical blood volume as less as
0.1 ml

5. INCIDENCE
• 15 – 20% of all the Rh Incompatible
pregnancies
• Protection-
Genetic
Other incompatibility
Variable expression of antigenicity

6. Pathophysiology of
isoimmunisation
• These circulating “anti-D” antibodies enter
fetus
• They will attack fetal RBCs that are rhesus
positive
• This causes RBC destruction (hemolysis)
• This leads to fetal anemia
• Fetus does not get hyperbilirubimemia
• Manifests as hydrops and fetal loss

7. Management of
Rh negative gravida
• Careful history
• Previous pregnancy losses
• h/o blood transfusions
• Check husband’s blood
group and Rh factor
• Check anti-D antibodies
by indirect coombs test
• If no antibodies at
‘booking’, then repeat
titres at 28, 36 weeks
Coomb’s test

8. Prophylactic Anti-D
• Prophylactic antenatal anti D at 28, 34 weeks
300 IU injection ( neutralises approx 30 ml
of blood)
• Following any episode of antepartum
haemorrhage
• Miscarriage, Ectopic pregnancy
• Amniocentesis / CVS / FBS
• Delivery – normal and LSCS

9. 6/7/2015 hcb 9
Liley Graph
ZONE 3
ZONE 2
ZONE 1
WEEKS
27 30 32 34 36 38 40 42
0.01
0.1
1.0
0.07
0.3
OD
Intrauterine Death Risk
Indeterminate
Rh Negative
[unaffected]
Rh Positive
[affected]

10. Anti – D:
Mechanism of Action
• The Rh positive fetal RBCs
that enter the maternal
circulation are destroyed by
the anti D
• Thus, the D antigen is not
allowed to be presented to the
maternal immune system
• Prevents ‘sensitisation’

11. MANAGEMENT OF RH
SENSITISATION
• GOALS :
• Find sensitisation
• INUTERO TRANSFER TO TERTIARY CARE
CENTRE
• Foetal Monitoring by USG
• Serial maternal coombs tests in dilution
• Amniocentasis cordocentasis
• INTRAUTERINE BLOOD TRANSFUSION
• surfectant induction by cortico steroids
• Delivery

12. Rh Sensitised Pregnancy
Rh antibodies
positive
Critical titre 1:16
Titres < 1:32
Titres 4 weekly till
24 wks and 2 wkly
till term
Titres > 1:32
Serial fetal MCA
Dopplers every 1-
2 wks

13. Rh Sensitised Pregnancy - 2
MCA Doppler
Velocimtery
Peak Systolic
Velocity
MCA PSV 1.5
MoMs and above
Fetal Blood
Sampling and
consider IUT
If no facilities for
FBS,
amniocentesis
MCA PSV less
than 1.5 Moms
Monitor MCA
PSV 1-2 wkly

14. THANK YOU