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Title: Rh negative pregnancy

  • (MBBS, MD, DGO)

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

  • 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

... 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
  • An individual either has or does not have the D
    antigen on the surface of their red blood cells

... 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.

... 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

... 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

... 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

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

... 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

Erythroblastosis Fetalis (Red Cell
  • the first description of erythroblastosis fetalis
    (hemolytic disease of the newborn) dates back to
  • 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

  • Two commonest systems for blood group
  • 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)

... Pathophysiology ...
... Pathophysiology ...
... 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
  • 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)

... Pathophysiology ...
... 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
  • 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)

... Pathophysiology ...
... 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

... 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
  • The initial maternal response to Rh sensitisation
    is low levels of immunoglobulin (Ig) M antibodies

... 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

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

... Pathophysiology ...
  • Sequence of inutero events
  • Maternal IgG enters foetal circulation via
  • 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

... 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

(No Transcript)
... 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
  • 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

... Pathophysiology
  • The aforementioned risk depends on the 3 main
  • 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

Maternal Immunologic Response
  • 30 of Rh-negative individuals appear to be
    immunologic nonresponderswho will not become
  • 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.

  • This includes history taking, clinical
    examination, appropriate investigations, and
  • 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

... 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

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

... Management ...
  • Other aspects of the history to be explored
  • 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

... 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

... 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

... 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

... Management ...
  • ... The unsensitised Rh-negative woman
  • Precautions during delivery
  • Ensure consultation with neonatologist
  • Don't give oxytocics at delivery of anterior
  • If manual removal of placenta is required, do so
  • 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

... 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

... 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

Rosette Test ... The unsensitised Rh-negative
Negative rosette
Positive rosette
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
  • Risk factors only identify 50

Acid Elution (KB)Test ... The unsensitised
Rh-negative woman
(No Transcript)
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

Management of the Unsensitized Rh-Negative
Pregnant Woman
Determining Fetal Rh D Status
... Management ... The sensitised Rh negative
  • For sensitised women, management is guided by the
  • 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

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

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)

Direct Coombs Test (To detect sensitized RBCs in
Indirect Coombs Test (To detect anti-D
antibodies in Maternal Serum)
... 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
  • Obtain the ABO and Rh group of the husband. If
    negative, no further testing is needed. If

... 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
  • 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

... Management ...
  • ... The sensitised Rh-negative woman ...
  • ... No previous history of affected foetus
  • If it rises before 34 weeks, further testing
  • 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

... 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

... 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

... 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

... Management ...
... 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,

... 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

Middle Cerebral Artery Dopplers
  • ... The sensitised Rh-negative
  • 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

Normal vs abnormal MCA-PSV
Normal MCA Doppler
... 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
  • 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

  • ... 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

Rh Sensitised Pregnancy
... Management ...
Spectrophotometry charts
Not accurate before 26 weeks GA
Can be used from 14th to 40th week GA Sensitivity
10 superior to Liley curve
(No Transcript)
Liley Curve
  • Zone I fetus very low risk of severe fetal
  • 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

... Management ...
... 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
  • Amount to be transfused in mL is (GA-20) x 10
    where GAgt 20 weeks

Intravascular IUBT ... The sensitised Rh-negative
woman ...
... 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.

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

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

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

(No Transcript)
... 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
  • External cephalic version Up to 6 chance of
    sensitisation. Dose is 300 mcg

... 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

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

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

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

  • 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
  • Creation of special fora/groups for Rh-negative
    people where potential Rh-negative spouses can be

  • Rhesus alloimmunisation is a real problem and
    real efforts need to be made to mitigate its
  • 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.

  1. Salem L, Singer KR. Rh Incompatibility.
    Updated Feb 06, 2014. Available from
  2. Levine P, Stetson RE. An unusual case of
    intragroup agglutination. JAMA. 1939. 113126-7.
  3. Landsteiner K, Wiener AS. An agglutinable factor
    in human blood recognised by immune sera for
    rhesus blood. Proc Soc Exp Biol Med. 43 223-4.
  4. Roman AS. Late pregnancy complications. In
    Decherney AH, Nathan L, Laufer N, Roman AS,
    editors. Current Diagnosis Treatment
    Obstetrics Gynaecology. 11th ed. United States
    McGraw-Hill Companies Inc 2013 250-266.
  5. Okeke TC, Ocheni S, Nwagha UI, Ibeghulam OG. The
    prevalence of Rhesus negativity among pregnant
    women in Enugu, Southeast Nigeria. Niger J Clin
    Pract. 2012 Oct-Dec 15(4) 400-2

... References ...
  1. Onwuhafua JA. Pregnancy in Rhesus Negative Women
    in Kaduna, Northern Nigeria. Trop J Obstet
    Gynaecol. 2004 21(1) 21-23
  2. Adeyemi AS, Bello-Ajao HT. Prevalence of Rhesus
    D-negative blood type and the challenges of
    Rhesus D immunoprophylaxis among obstetric
    population in Ogbomosho, Suthwestern Nigeria. Ann
    Trop Med Public Health. 2016 9(1)12-15.
  3. Saxena R, editor. Bedside Obstetrics and
    Gynaecology. 1st ed. New Delhi Jaypee Brother
    Medical Publishers (P) Ltd 2010 105-120.
  4. Scheier M, Hernandez-Andrede E, Carmo A,
    Dezerenyz V, Nicholaides KH. Prediction of fetal
    anemia in rhesus disease by measurement of fetal
    middle cerebral artery peak systolic velocity.
    Ultrasound Obstet Gynecol. 2004 23 432-436.

... References ...
  1. Zimmermann R, Durig P, Carpenter RJ, Jr, Mari G.
    Logitudinal measurement of peak systolic velocity
    in the fetal middle cerebral artery for
    monitoring pregnancies complicated by red cell
    alloimmunization A prospective multicentre trial
    with intention to treat. Br J Obstet Gynaecol.
    2002 109 746-752
  2. Bullock R, Martin WL, Coomarasamy A, Kilby MD.
    Prediction of fetal anemia in pregnancies with
    red-cell alloimmunization comparism of middle
    cerebral artery peak systolic velocity and
    amniotic fluid OD450. Ultrasound Obstet Gynecol.
  3. Pereira L, Jenkins TM, Berghalla V. Conventional
    management of maternal red cell alloimmunization
    compared with management by Doppler assessment of
    middle cerebral artery peak systolic velocity. Am
    J Ostet Gynecol. 20031891002-1006

... References
  1. Pessel C, Tsai MC. The Normal Pueperium. In
    Decherney AH, Nathan L, Laufer N, Roman AS,
    editors. Current Diagnosis Treatment
    Obstetrics Gynaecology. 11th ed. United States
    McGraw-Hill Companies Inc 2013 190-213
  2. Kolialexi A, Tounta G, Mavrou A. Noninvasive
    fetal RhD genotyping from maternal blood. Expert
    Rev Mol Diagn. 2010 Apr 10(3) 285-96
  3. Rapidtest Rh Test kit. Available from
  4. Gonsorcik VK, Zhou L. Rh Typing. Updated Nov
    06 2013. available from http//emedicine.medscap
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