Rh incompatibility or iso-immunization is very uncommon. This presentation deals with some basics about blood groups and pathogenesis of it. This will be useful for under and postgraduates in the field of obstetrics.

1. Dr.Suresh Babu Chaduvula
Professor
Department of Obs & Gyn
College of Medicine
KKU, Abha, Saudi Arabia

3.  Karl Landsteiner – Proposed Blood Group
Sysytem
 Awarded Nobel prize in 1930
 Landsteiner and S.Weiner – discovered
Rhesus system in Rhesus monkeys.

4.  RBC cell surface has antigens called
Agglutinogens or isoagglutinogens and
plasma contains antibodies called
Agglutinins or isoagglutinins.
 A positive woman will have A antigen and
anti B antibodies.
 Rhesus positive mothers means D antigen
positive.
 Rhesus negative means D antigen negative
mothers.

7.  There are 5 Rhesus antigens – D, C,c,E and e.
 Out of which D antigen is most powerful
antigen.
 Other antigens like Kell and Duffy antigens.
 Anti- kell is very serious.

9.  Sensitization of maternal immune system to
produce antibodies after exposure to fetal
RBC antigens.
 Allo or Isoimmunisation – means immune
response to foreign antigens from the same
species.
 Prevalence is 1%.

11.  1. Mismatched blood transfusion
 2.Feto maternal hemorrhage following
delivery, ectopic pregnancy, abortions.
 3. Invasive procedures like Chorionic villous
sampling, Amniocentesis in pregnant mothers
 4. APH – Placenta Previa, Abruption of
placenta
 5. External cephalic version
 6. Intrauterine fetal death

12.  Feto-maternal hemorrhage of Rh positive cells
enter into maternal circulation and will produce
anti – D antibodies Ig M type initially called –
Sensitisation.
 After a minimum period of 3 months IgG
antibodies are produced which are capable of
crossing placental barrier.
 IgG antibodies attack and destroy fetal RBCs in
spleen and produce Hemolytic anemia of
Newborn.
 Anemia will produce erythropoiesis in liver
leading to erythroblast production called
Erythroblastosis fetalis.

13.  In a mother who is already sensitised will
have a very severe hemolytic anemia and
hyperbilirubinemia called Icterus Gravis
Neonatorum.
 If this unconjugated bilirubin crosses blood
brain barrier it will stain basal ganglia called
Kernicterus
 And hypo-proteinemia which will lead to
changes in hemeodynamics results in
accumulation of fluid all over the body and
also in body cavities called Hydrops fetalis.

16.  Antenatally at 28 and 34 weeks Anti D
Immunoglobulin of 300 micrograms should be
given.[ decreases immunization by 0.2%]
 Anti D Immunoglobulin of 300 micrograms
should be given within 72 hours called
RhoGAM.[ decreases immunization by 1.5%]
 Following all invasive procedures also it
should be given.
 300 micrograms can protect from 30 ml of
bleed.

19.  1. Increases with each subsequent pregnancy
 2. Depends on paternal zygosity
 3. Amount of feto-maternal bleeding
 4.ABO incompatibility.

20.  Initially sensitization occurs in 1st pregnancy.
 Later due to memory in the immune system
response for antibodies will be very high.

23.  Amount of antibody production varies with
the amount of fetal RBCs entered into
maternal circulation.
 Quantity tests for FMH is done by
1.Kleihuer-Betke test
2.Flow cytometry

24.  It occurs in mothers with ‘O’ blood group.
 The antibodies in this group are weak
hemolysins.
 These can attach to only few fetal RBCs
 It may produce only mild hyper bilirubinemia
but not Hydrops.
 These antibodies and mild hemolysis will
decrease Rh iso- immunization and
hemolysis.

25.  Do Blood group and type of partners
 Anti D immunoglobulin at 28/ 34 weeks
 Anti D immunoglobulin within 72 hours
 Assess amount of feto-maternal hemorrhage
and if amount is more than 30 ml adjust the
dose.

26.  Assess accurately gestational age by USG
 Blood group and typing of partners
 Assess Antibody titer – by Indirect Coomb’s
test – every 2-4 weeks
Amniocentesis – at a critical titer 1:16 to
assess the hemolytic anemia

28.  To determine the amount of bilirubin which
is produced by fetal hemolysis and is
secreted by secretions from fetal body.
 Spectrophotometric analysis is used to find
out level of bilirubin in amniotic fluid.
 Bilirubin causes shift of optical density from
linearity. Shift is greatest at 450 nanometer.
 Degree of shift at 450 nm called Delta OD
[OD 450] indicates degree of hemolysis.

29.  Delta OD at 450 should be plotted in Liley
chart.[used between 27 to 41 weeks]
 I t has X axis –indicates gestation in weeks
and Y axis about Delta OD.
 It has 3 zones called Low, Mid and High Zone.
 Delta OD may fall either of the zones and
gives approximate time for time of delivery.
 This chart also helpful in preventing
iatrogenic preterm delivery.

31.  Low zone indicates - mild anemia -
 Mid zone –mild to severe anemia
 High zone – severe anemia and impending
fetal death within 7-10 days.

32.  Like a normal pregnancy deliver at 38 weeks
 Do regular ultrasound and may have to
repeat amniocentesis.
 Fetal well being tests – NST, CTG, Biophysical
profile, Doppler study.

33.  High mid and High zone will require
CORDOCENTESIS – to assess fetal hemoglobin,
hematocrit , platelets and group and type,
reticulocyte count fetal transfusion through
umbilical vein and delivery.
Transfusion of O negative fresh blood if
hematocrit is less than 30%.

34.  1. Intra peritoneal
 2. Intra vascular – umbilical vein
 Transfusion can be given till fetal hematocrit
becomes normal till the risk of prematurity is
crossed.

35.  A] Ultrasound – to determine hydropic changes
like
1. scalp edema
2. Anasarca
3. Effusions
4. Hepato and spleenomegaly
5. Umbilicalomegaly
6. Placentomegaly
B] Doppler Velocimetry –
Assess peak systolic velocity in middle
cerebral artery, aorta, vena cava and umbilical
vein. It will be increased in severe anemia.
C] CTG – NST
D] Biophysical profile

37.  Low Zone & Low Mid Zone - – Deliver at 38
weeks.
 High mid zone High Zone – Deliver at 34
weeks electively by cesarean section .
 Arrange adequate amount of O negative
fresh blood for the newborn.
 Inform the neonatologist prior to the
delivery.
 Higher tertiary centers is ideal place for
delivery.

39. THANK YOU ALL
AND
ALL THE BEST