Rh negative pregnancy

1
MANAGEMENT OF RHESUS NEGATIVE PREGNANCY

• DR MALLESWAR RAO K
• (MBBS, MD, DGO)
• FORMER CONSULTANT CSS HOD
• DEPARTMENT OF OBSTETRICS GYNAECOLOGY
• ESI HOSPITAL, SANATHNAGAR
• HYDERABAD

2
Outline

• Introduction
• Epidemiology
• Pathophysiology
• Management
• Problems in our setting
• Recommendations
• Conclusion
• References

3
Introduction

• The Rhesus (Rh) blood group system is one of the
  35 current human blood group systems
• It's the second most important system after the
  ABO system
• At present, the Rh system consists of 50 defined
  blood group antigens (Ag), among which the five
  Ag D, C, c, E, e are the most important

4
... Introduction ...

• The D Ag, also called the Rh factor is the most
  immunogenic1 of them though the others are
  still clinically relevant
• The Rh factor is a red cell surface antigen named
  after the rhesus monkey in which it was first
  discovered.1
• An individual either has or does not have the D
  antigen on the surface of their red blood cells
  (RBCs)

5
... Introduction ...

• The status is usually indicated by the suffices
  Rh for those that have, or Rh- for those who
  lack the D antigen
• These suffices are attached to the ABO blood type
  
• An Rh-negative pregnant woman is one who lacks
  this antigen on the surface of their red cells.

6
... Introduction ...

• Historical time line
• 1937 Rh blood type discovery by Karl Landsteiner
  Alexander Wiener, and noted to be distinct from
  ABO blood type
• 1939 The D antigen was incidentally discovered
  but yet unnamed. This followed a case of
  haemolytic disease of the newborn observed in a
  the infant of a 25 year old G2 P1 woman, blood
  group O who received O type blood
• This case was subsequently published2 by Philip
  Levine and Rufus Stetson

7
... Introduction ...

• ... Historical time line ...
• 1940 This unnamed factor was realised to be
  similar to the earlier discovered blood type and
  a connection was made to it3
• 1946 Exchange transfusion created by Wiener for
  treatment of Rh disease
• 1960 The concept of anti-RhD for the prevention
  of Rh disease was proposed by Ronald Finn
• 1963 First successful intrauterine transfusion
  for treatment of Rh disease was carried out by
  Sir William Liley

8
... Introduction

• ... Historical time line
• 1964 First prophylactic injection for Rh disease
  was given
• 1968 Immunoglobulin G antibody was first
  approved for use in USA (as RhoGAM) and UK _at_300
  mcg within 3 days postpartum
• 1973 Reports in the USA said 50,000 babies'
  lives had been saved since approval
• 1981 Rh IgG approved for routine postpartum and
  antepartum administration by the US Food and Drug
  Administration

9
Epidemiology

• Globally, the Basque population (of Spain) has
  the highest incidence of Rh negativity
  (30-35)4
• Otherwise,
• Whites 15-16
• African Americans 8
• Black Africans 4
• Asians and others, 2 or less

10
... Epidemiology

• Nigerian studies
• 4.5 prevalence rate at Enugu,5 Southeast
• 0.7 incidence rate at Kaduna,6 North
• 5.5 prevalence rate at Ogbomosho,7 Southwest

11
Erythroblastosis Fetalis (Red Cell
Alloimmunization)

• the first description of erythroblastosis fetalis
  (hemolytic disease of the newborn) dates back to
  1609
• until the early 1900s that the role of
  alloimmunization in the pathogenesis of
  erythroblastosis was established
• In the past, Rh alloimmunization also has been
  referred to as Rh sensitization or Rh
  isoimmunization.

12
Pathophysiology

• Two commonest systems for blood group
  classification8
• ABO system
• Rhesus system
• ABO system Groups A, B AB, O antigen (Ag)
• Rhesus system C, c, D, E, e and G.4
• There's no 'd' Ag. The letter represents absence
  of 'D' Ag
• The D antigen is considered to be the most
  immunogenic (aka Rh factor)

13
... Pathophysiology ...
14
... Pathophysiology ...
15
... Pathophysiology ...

• There are two possible alleles for each of the c
  or C, D and e or E
• An individual inherits one haplotype from each
  parent
• Rh positive presence of at least one of either
  C, D or E antigens regardless of the combination
  (ie, homozygous or heterozygous)
• Rh negative cde/cde genotype (always homozygous)

16
... Pathophysiology ...
17
... Pathophysiology ...

• The D antigen
• The Rh-positive father may be homozygous (45) or
  heterozygous (55) for D
• If homozygous for D, all children will test
  positive
• If heterozygous, his children will have a 50
  chance of being RhD-positive
• Thus if 'D' antigen is specifically tested, its
  absence will give a negative result regardless of
  the presence of the other antigens (C, E)

18
... Pathophysiology ...
19
... Pathophysiology ...

• The amount of foetal blood necessary to produce
  Rh incompatibility varies, but as little as 0.1
  mL of Rh cells have been documented.4
• Studies have suggested that up to 30 of persons
  (non-responders) with Rh- blood never develop Rh
  incompatibility even when challenged with large
  volumes of Rh blood1
• Rh alloimmunisation occurs by 1 of 2 mechanisms
• After incompatible blood transfusion

20
... Pathophysiology ...

• After foeto-maternal haemorrhage between mother
  and an incompatible foetus
• Foeto-maternal haemorrhage may occur during
  pregnancy (10) or delivery (90)1
• Notwithstanding, foetal RBCs have been detected
  in the maternal blood in all three (7, 16, 29)
  trimesters without an apparent predisposing
  factor4
• The initial maternal response to Rh sensitisation
  is low levels of immunoglobulin (Ig) M antibodies
  (Ab)

21
... Pathophysiology ...

• These are confined to maternal circulation being
  unable to cross the placental barrier
• Within 6 weeks to 6 months, IgG Ab are formed
• These are able to cross the placenta and destroy
  foetal Rh-positive cells
• Therefore, first-born infants with Rh-positive
  blood type are not affected
• The short period of 1st exposure of mother to
  foetal RBCs is insufficient for production of
  significant IgG Ab response

22
... Pathophysiology ...

• Subsequent pregnancies may trigger a rapid
  robust Ab response - Anamnestic response
• Anamnestic theories
• Grandmother theory
• Sensibilization theory
• Maternal O blood type appears particularly
  protective

23
... Pathophysiology ...

• Sequence of inutero events
• Maternal IgG enters foetal circulation via
  placenta
• Destruction of foetal red cells occur - foetal
  anaemia HCTlt30
• Haem is formed and converted to bilirubin
  foetal hyperbilirubinaemia
• Both are neurotoxic, but effectively cleared by
  placenta and metabolised by the mother
• Extramedullary erythropoeisis is stimulated
• Immature erythroblasts are produced

24
... Pathophysiology ...

• When cell destruction exceeds production
• Severe anaemia occurs
• More demand on extramedullary sites to produce
  more red cells hepatosplenomegaly
• Heart failure eventually results, with ascites,
  oedema and pericardial effusion
  erythroblastosis foetalis
• Hydrops foetalis, occurs when the haematocrit
  falls below 15. Often results in foetal death
  shortly before or after birth
• Male to Female foetus 13.1 to 1

25
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26
... Pathophysiology ...

• The risk and severity of sensitisation response
  increases with each subsequent pregnancy
  involving an ABO-compatible foetus with
  Rh-positive blood
• Without prophylaxis, this risk is 16 after two
  deliveries
• 1.5-2 occur antepartum
• 7 within 6 months of delivery
• 7 manifest early in 2nd pregnancy
• With prophylaxis, the risk drops to 0.1

27
... Pathophysiology

• The aforementioned risk depends on the 3 main
  factors
• Volume of transplacental haemorrhage
• Extent of the maternal immune response
• Concurrent presence of ABO incompatibility
  (protective risk drops to 1.5-2)4
• Rh incompatibility is only of medical concern for
  females who are pregnant, or plan to get pregnant
  in future

28
Maternal Immunologic Response

• 30 of Rh-negative individuals appear to be
  immunologic nonresponderswho will not become
  sensitized
• ABO incompatibility diminishes the risk of
  alloimmunization to about 1.5 to 2.0 after the
  delivery of an Rh-positive fetus
• The effect is most pronounced if the mother is
  type O and the father is type A, B, or AB.

29
Management

• This includes history taking, clinical
  examination, appropriate investigations, and
  treatment
• Two groups of women are catered for
• Unsensitised Rh-negative women
• Sensitised Rh-negative women
• There is usually no specific finding on the
  history and clinical examination for the woman
  that is not sensitised

30
... Management ...

• For the sensitised woman, her presentation would
  depend on whether or not she has a previously
  affected infant. This also guides management.
• Some events have been found to increase the
  chances of formation of anti-D antibodies in
  Rh-negative women
• The goal of the history therefore, is to
  establish or exclude the occurrence of such
  events

31
... Management ...

• Potentially sensitising events
• Abortion
• Invasive procedures (amniocentesis, chorionic
  villus sampling)
• Abdominal/pelvic trauma
• Antepartum haemorrhage (placenta praevia,
  abruptio)
• Intrauterine foetal demise
• Multiple gestation
• Manual removal of the placenta
• Ectopic pregnancy
• Caesarean delivery

32
... Management ...

• Other aspects of the history to be explored
  include
• Prior blood transfusion
• Rh blood type of patient and spouse
• All previous pregnancies, outcomes, interventions
• History of hydrops 90 chance recurrence
• Previous administration of Rh IgG
• Mechanism of injury in cases of maternal trauma
  during pregnancy
• Presence of vagina bleeding
• Prior invasive procedure

33
... Management ...

• The objective of antenatal management is
• Prevention of Rh alloimmunisation in the
  Rh-negative unsensitised woman
• Early detection and treatment of foetal anaemia
  in the sensitised woman
• Sensitisation is determined via the indirect
  Coombs test, otherwise called antibody screen

34
... Management ...

• The unsensitised Rh-negative woman
• History may be uneventful with patient hearing
  for the first time of her Rh-negative group
• First, determine husband's ABO and Rh group.
• If negative, manage as any other pregnancy. No
  further investigation required
• If positive, screen woman for alloimmunisation at
  contact.

35
... Management ...

• ... The unsensitised Rh-negative woman
• If the antibody screen is negative, repeat at 20,
  24 28 weeks
• If still negative by 28 weeks, 300 mcg of Rh IgG
  is given
• A repeat dose is given after each invasive
  procedure, or after 12 weeks of last dose if
  pregnancy lasts that long
• If a positive result is recorded at any time, the
  patient is managed as a sensitised Rh-negative
  woman

36
... Management ...

• ... The unsensitised Rh-negative woman
• Precautions during delivery
• Ensure consultation with neonatologist
• Don't give oxytocics at delivery of anterior
  shoulder
• If manual removal of placenta is required, do so
  gently
• If blood transfusion is indicated, use
  Rh-negative blood only
• Early clamping of umbilical cord is indicated
• Leave a long length of cord, about 15 to 20 cm

37
... Management ...

• ... The unsensitised Rh-negative woman
• Postpartum management
• Involve the neonatologist
• Send cord samples for ABO/Rh typing, DCT, Hb,
  bilirubin levels, peripheral smear
• If foetus is Rh-negative, no further intervention
• If foetus is Rh-positive, determine the dose of
  Rh IgG to be administered by a 4-step laboratory
  procedure

38
... Management ...

• ... The unsensitised Rh-negative woman
• The 4-step laboratory procedure
• Rosette foetal RBC screen for FMH. If positive,
• Acid elution (Kleihauer-Betke) test to quantify
  the RBCs in maternal circulation
• Estimate the volume of FMH (50 x foetal RBCs)
• Calculate the dose of Rh IgG to be given within
  72 hours of delivery

39
Rosette Test... The unsensitised Rh-negative
woman
Negative rosette
Positive rosette
40
Kleihauer-Betke Test

• ... The unsensitised Rh-negative woman
• fetal RBC in maternal circulation
• Fetal erythrocytes contain Hbg F which is more
  resistant to acid elution than HbgA so after
  exposure to acid, only fetal cells remain can
  be identified with stain
• 1/1000 deliveries result in fetal hemorrhage gt
  30ml
• Risk factors only identify 50

41
Acid Elution (KB)Test... The unsensitised
Rh-negative woman
42
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43
Kleihauer Calculations

• ... The unsensitised Rh-negative woman
• Fetal red cells MBV X maternal Hct X fetal
  cells in KB
• 
  newborn Hct
• MBV maternal blood volume (usually 5000ml)
• Fetal cells X 2 whole blood

44
Management of the Unsensitized Rh-Negative
Pregnant Woman
45
Determining Fetal Rh D Status
46
... Management ...The sensitised Rh negative
woman

• For sensitised women, management is guided by the
  following
• Presence or absence of history or affected foetus
  in previous pregnancy (e.g. with severe anaemia
  or hydrops)
• Maternal antibody titres (where no prior history)
• Sensitisation may be determined by doing an
  antibody screen using indirect Coombs test

47
Gold Standard Test... Management ...The
sensitised Rh negative woman

• Indirect Coombs
• -mix Rh(D) cells with maternal serum
• -anti-Rh(D) Ab will adhere to Rh(D) cells
• -RBCs then washed suspended in Coombs serum
  (antihuman globulin)
• -RBCs coated with Ab will be agglutinated
• Direct Coombs
• -mix infants RBCs with Coombs serum
• -maternal Ab present if cells agglutinate

48
Rh(D) Antibody Screen... Management ...The
sensitised Rh negative woman

• Serial antibody titres q2-4 weeks
• If titre 116 - amniocentesis or MCA dopplers
  and more frequent titres (q1-2 wk)
• Critical titre sig risk hydrops
• amnio can be devastating in this setting
• U/S for dating and monitoring
• Correct dates needed for determining appropriate
  bili levels (delta OD450)

49
Direct Coombs Test (To detect sensitized RBCs in
Neonate)
50
Indirect Coombs Test (To detect anti-D
antibodies in Maternal Serum)
51
... Management ...

• The sensitised Rh-negative woman
• No previous history of affected foetus
• The history might include some of the previously
  mentioned sensitising events
• Risk of foetal anaemia is proportional to
  maternal anti-Rh antibody titre
• This relationship is lost in subsequent
  pregnancies
• Obtain the ABO and Rh group of the husband. If
  negative, no further testing is needed. If
  positive,

52
... Management ...

• ... The sensitised Rh-negative woman ...
• ... No previous history of affected foetus...
• Screen for alloimunisation. If positive, obtain
  Ab titres
• If below the critical titre, obtain monthly
  titres
• If still below critical level by 36th week,
  pregnancy may continue to term, but not allowed
  to be postdated
• If it rises beyond critical value after 34 weeks,
  deliver immediately

53
... Management ...

• ... The sensitised Rh-negative woman ...
• ... No previous history of affected foetus
• If it rises before 34 weeks, further testing
  includes
• Peak systolic velocity of the middle cerebral
  arteries using Doppler
• Amniocentesis for analysis and spectrophotometry
• Ultrasound examination of foetus
• Percutaneous umbilical cord blood sampling
  (cordocentesis) for HCT, Rh

54
... Management ...

• ... The sensitised Rh-negative woman ...
• Previously affected foetus
• The history may include, amongst others, that of
  a stillborn neonate, one admitted for
  phototherapy or exchange blood transfusion.
• One needs to be proactive to prevent recurrence,
  and have a high index of suspicion
• Her Rh type should be established as well as
  sensitisation

55
... Management ...

• ... The sensitised Rh-negative woman ...
• ... Previously affected foetus
• Evaluation should start early at least 4 weeks
  to anniversary of prior affected foetus
• The anti-D titres cannot predict the development
  of foetal anaemia, thus other tests are indicated
• Cordocentesis may be indicated to determine
  foetal HCT, and Rh genotype if father is
  heterozygous for D
• If the foetus is determined to have the D Ag,
  there is a risk of haemolytic disease and sequelae

56
... Management ...

• ... The sensitised Rh-negative woman ...
• ... Previously affected foetus
• Amniocentesis may be done for amniotic fluid
  spectrophotometry and assay
• Initiate middle cerebral artery Doppler (MCAD)
  surveillance from 18 weeks

57
... Management ...
58
... Management ...

• ... The sensitised Rh-negative woman
• Middle Cerebral Artery Doppler (MCAD) Velocimetry
• Accurate non-invasive screening tool for
  detecting moderate to severe foetal anaemia
• A sensitivity of 100 and a 12 false positive
  rate for anaemia
• Use has resulted in up to 809 reduction in
  invasive testing (i.e., amniocentesis,
  cordocentesis)

59
... Management ...

• ... The sensitised Rh-negative woman
• Middle Cerebral Artery Doppler (MCAD) Velocimetry
• Not useful before 18 weeks of gestation RES too
  immature to haemolyse enough cells to cause
  significant anaemia9
• Not a reliable predictor of severe anaemia after
  35 weeks GA10
• Found to be similar11 or better12 than
  amniotic fluid OD450 in prediction of anaemia

60
Middle Cerebral Artery Dopplers

• ... The sensitised Rh-negative
  woman
• Measures peak velocity of blood flow
• Anemic fetus preserves O2 delivery to brain by
  increasing flow
• Sensitivity of detecting severe anemia when MCA
  gt1.5 MoM approaches 100
• Not reliable gt 35 weeks GA

61
Normal vs abnormal MCA-PSV
Normal MCA Doppler
62
... Management ...... The sensitised Rh-negative
woman ...

• Results MCAD Velocimetry4
• Unaffected/mildly affected foetus
• Normal MCAD. Doppler is repeated monthly. Deliver
  at or near term after lung maturity. Low risk of
  IUFD
• Moderately affected
• MCAD about 1.5 multiples of median (MoM). Repeat
  1-2 weekly. Deliver after lung maturity.
  Enhancement of lung maturity may be necessary
• Severely affected
• MCAD gt1.55 MoM or has frank evidence of foetal
  hydrops. Foetus needs help to attain lung
  maturity before delivery. High risk of IUFD

63
Amniocentesis

• ... The sensitised Rh-negative woman
• Critical titre/previous affected infant
• Avoid transplacental needle passage
• Bilirubin correlates with fetal hemolysis
• ? optical density of amniotic fluid _at_ 450nm on
  spectral absorption curve
• Data plotted on Liley curve

64
Rh Sensitised Pregnancy
... Management ...
65
Spectrophotometry charts
Queenan
Liley
Not accurate before 26 weeks GA
Can be used from 14th to 40th week GA Sensitivity
10 superior to Liley curve
66
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67
Liley Curve

• Zone I fetus very low risk of severe fetal
  anemia
• Zone II mild to moderate fetal hemolysis
• Zone III severe fetal anemia with high
  probability of fetal death 7-10 days
• Liley good after 27 weeks
• 98 sensitive for detecting anemia in upper zone
  2/ zone 3

68
... Management ...
69
... Management ...... The sensitised Rh-negative
woman ...

• Intrauterine Blood Transfusion8
• Recommended treatment for severe (haemolytic)
  anaemia inutero
• Typically carried out between 18 and 35 weeks GA
• May be given intraperitoneal or intravascular
• O RhD negative packed cells with HCT of 80 is
  used
• Amount to be transfused in mL is (GA-20) x 10
  where GAgt 20 weeks

70
Intravascular IUBT... The sensitised Rh-negative
woman ...
71
... Management ...

• ... The sensitised Rh-negative woman
• Postpartum management of the neonate
• Baby, if alive should be admitted into the
  neonatal intensive care unit
• An urgent exchange blood transfusion is indicated
  in moderate to severely affected neonates
• Phototherapy for mild affectation.

72
Antenatal Steroids

• If preterm delivery lt36 wks may be predicted,
  then antenatal steroids must be given to enhance
  fetal lung maturity
• 2 doses of betamethasone 12 mg
• 24 hours apart
• Careful blood sugar monitoring in GDM
• May also cause hyperacidity

73
Delivery

• Most commonly with Rh sensitised pregnancies
  LSCS
• May try induction of labour
• Continuous FHR monitoring
• Early recourse to LSCS is any doubts
• Neonatologists present at delivery

74
Neonatal Management

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

75
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76
... Management ...

• Special foeto-maternal risk states4
• Abortion Up to 5 chance of sensitisation. Fifty
  microgram is recommended
• Invasive foetal procedure Up to 11 of
  sensitisation. A dose of 300 mcg is recommended
• Antepartum haemorrhage 300 mcg stat, to be
  repeated 12 weeks later if pregnancy lasts that
  long
• External cephalic version Up to 6 chance of
  sensitisation. Dose is 300 mcg

77
... Management

• Delivery with foeto-maternal haemorrhage
• The normal amount of foetal blood that enters the
  maternal circulation is lt0.5 mL.13
• Dose of Rh IgG given _at_ 300 mcg will neutralize
  nearly 30 mL whole foetal blood (or 15 mL Rh
  foetal RBCs)
• Management is guided by the estimated volume of
  FMH determined by the 4-step lab tests
• Dose of Rh IgG given after sensitisation is at
  least 20 mcg/mL of foetal RBCs1

78
Recent Advances

• Non-invasive foetal RhD genotyping (from foetal
  cell-free DNA in maternal circulation)14
• Point-of-care-tests (POCT), i.e., rapid tests for
  determining Rh status15
• A lower 50 mcg dose preparation of Rh IgG for use
  following first trimester abortions1
• Concept of partial D and weak D antigens (usually
  test positive, but can also form anti-Rh
  antibodies)16

79
Take home points

1. Every woman of childbearing age should have her
   ABO and Rh types done at first contact
2. Obtain the ABO/Rh types for husbands of women
   found to be Rh-negative
3. Ensure ICT is done at 20, 24 and 28 weeks of
   pregnancy with appropriate prophylaxis
4. A single postpartum dose may be inadequate in
   cases of severe foeto-maternal haemorrhage

80
Problems in our setting

• High cost of the immunoglobulin
• Lack of resources to adequately investigate and
  monitor foetus inutero
• Low turnout for antenatal clinics missed cases
• Poor documentation of prior sensitising events
  some are yet to fully grasp the import
• Loss of case notes

81
Recommendations

• Advocacy for partnership by Government and NGOs
  to help subsidize the cost of the immunoglobulin
• Special insurance cover for Rh-negative women to
  ensure ease of procurement when needed
• Involvement of clergy as part of premarital
  counsellors
• Creation of special fora/groups for Rh-negative
  people where potential Rh-negative spouses can be
  met

82
Conclusion

• Rhesus alloimmunisation is a real problem and
  real efforts need to be made to mitigate its
  impact
• Although its incidence has decreased
  dramatically, yet the consequences of haemolytic
  disease of the newborn remain
• Great advancements have been made in the
  detection and management of this condition, and
  many of our Rh-negative women can now have a
  happy obstetric career.

83
THANK YOU
84
THANK YOU FOR LISTENING
85
References

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