ABO and Rh ISOIMMUNISATION : ABO and Rh ISOIMMUNISATION Professor. Surendra Nath Panda, M.S
Dept. of Obstetrics & Gynaecology
Berhampur-760004, Orissa, India The Basics Of Blood : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 2 The Basics Of Blood ANTIGEN
>400 Agglutinogens on the cell membrane W.B.C. & Platelet R.B.C. Plasma ANTIBODY
Natural & Immune Agglutinins/ Isoantibodies Antigen-Antobody reaction on the cell surface Hemolysis The Basics Of Blood : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 3 The Basics Of Blood Controlled by genes at unknown No. of chromosomal loci.
Appearance by 40 days of I.U. Life- unchanged till death.
Also present in tissues & tissue fluids.
Blood group system: A group of antigens controlled by a locus having a variable no of allele genes. Antigens: - The Basics Of Blood : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 4 The Basics Of Blood > 15 blood group systems are recognised :
ABO, Rh, Kell, Duffy, MN, P, Lewis, Lutheran, Xg, Li, Yt, Dombrock, Colton, Public antigens & Private antigens.
Blood type- means individual antigen phenotype which is the serological expression of the inherited genes
Most of these blood group antigens have been found to be associated with hemolytic disease.
However– ABO & Rh account for 98% Antigens: - The Basics Of Blood : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 5 The Basics Of Blood Alloantibodies / Agglutinins Natural
IgM Iso / immune antobodies
IgG Formed in response to foreign R.B.C. or soluble blood group substance. Antibodies: - The Basics Of Blood : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 6 The Basics Of Blood Antibodies are formed against most of the major group antigens & present in almost all individuals when the antigen is absent.
In most other minor systems, natural antibodies to the antigens are found occassionally but as their anitgenicity is low, the immune antibodies are also rare ( except –Kell & Duffy)
Mostly of them are IgM type.
React poorly at body temp. ( except anti-A & anti-B), but agglutinate R.B.C.s at 5-20°C
Usually do not cross placenta. Natural Antibodies: - The Basics Of Blood : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 7 The Basics Of Blood In contrast the immune or isoantibodies are IgG.
Best react at body temp. & readily cross placenta.
Most antibodies are complement binding notable exceptions being Rh & MN. Immune Antibodies: - Antibodies Can Be Detected by: - : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 8 Antibodies Can Be Detected by: - Saline agglutination test (SAT).
Tests using cells suspended in colloid media.
Tests using enzyme-treated cells- Rh & occasional antobodies.
Indirect antiglobulin ( Coomb’s test) - wide spectrum.
Antibodies may be Complete / Incomplete
Detected by SAT b, c, d ABO Blood Group System : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 9 ABO Blood Group System ABO system is controlled by allelic genes A1, A2, B, O located on the long arm of chromosome 9
The loci of ABO & H are not genetically linked
A1 & A2 genes perform same function but have a different rate constant
The O gene is an amorph & functionaly silent
The H antigen is a precursor to A & B
Secretors & nonsecretors – Se & se genes control the production of a flucosyl transferase, which controls the production of H, A & B antigens in tissues ABO Blood Group System : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 10 ABO Blood Group System ABO System & Pregnancy : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 11 ABO System & Pregnancy Majorities of hemolytic diseases are due to ABO incompatibility
Foetus inherits one gene from each parent.
O + O = O, O + A= O or A, O + B= O or B, O + AB= A or B.
There is a 20% chance of ABO incompatibility of mother & foetus
Only 5% chance of developing hemolytic disease only in type A & B infants of type O mothers, that too only of milder forms ABO System & Pregnancy : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 12 ABO System & Pregnancy In foetus & newborn, RBCs have a decreased No. of H, A & B reactive sites
The foetal immunoglobulin production is low, so the plasma contains very little of anti-A & B agglutinins
Anti-A & B produced in the mother being natural are IgM molecules & so do not cross placenta.
In some type O adults, much of the anti-A & B and anti-AB (a cross reacting antibody, also called anti-C) isoagglutinins are of IgG class. ABO System & Pregnancy : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 13 ABO System & Pregnancy There is no adequate method of antenatal diagnosis.
Direct Coomb’s antiglobulin test may be negative in ABO haemolytic disease.
ABO haemolytic disease is frequently seen in infants of primigravidae & the chance of recurence is 87%.
The risk of stillbirth is not increased & no antenatal treatment is necessary.
Only 67% of affected infants will need any treatment. Rhesus Blood Group System : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 14 Rhesus Blood Group System First demonstrated by testing human blood with rabit anti sera against red cells of Rhesus monkey & classifying Rh negative & Rh positive.
However the underlying biochemical genetics is not well understood and the genotyping & phenotyping remains little confused
The genotype is determined by the inheritance of 3 pairs of closely linked allelic genes situated in tanderm on chromosome 9 & named as D/d, C/c, E/e (Fisher- Race theory) Rhesus Blood Group System : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 15 Rhesus Blood Group System The gene ‘d’ is an amorph & has no antigenic expression. So there are only five effective antigens.
But Weiner postulates a series of allelic genes at a single locus Rho (D), rh (C),rh (E), hr © & hr (e)
The updated system of Rosenfield refers these antigens as – Rh1, Rh2, Rh3, Rh4, Rh5
Subsequently less common antigens Cw, Du, Es have been found
The foetus inherits one gene from each group as a haplotype such as sets of Cde, cde etc from each parent Rhesus Blood Group System : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 16 Rhesus Blood Group System 12 sets of combinations & 78 genotypes are possible. Most frequent genotypes are –
Cde/cde(33%), Cde/cDe(18%), Cde/cDE(12%) cDE/cde(11%), cde/cde(15%), cdE/cde(1%), Cde/cde(1%)
Though several Rh genotypes and phenotypes have been described, for clinical & all practical purposes it is enough to know whether one is Rh POSITIVE or NEGATIVE against anti D sera. Rhesus Blood Group System : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 17 Rhesus Blood Group System Incidence of Rh negative varies in different races:
Mongoloids- nil, Chinese & Japanese- 1-2%, Indians-5%, Africans-5-8%, Causcasians-15-17% & Basques-30-35%.
The antigenic expressions of these genes are dependent on an interaction between R.B.C. membrane protein & phospholipid molecules resulting in a set of antithelical epitopes, the coresponding antigens, consisting of C/c, D/d, E/e.
The antigenic determinants form an intrinsic part of the red cell membrane protein structure. Rhesus Blood Group System : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 18 Rhesus Blood Group System C/c & E/e are weak antigens and impractical to match.
‘D’ is by far the most immunogenic in the Rh system excepting those that have the natural antibodies.
There is a rare type of Rh negative called Rh null who lack all known Rh antigens.
‘D’ antigen has no natural antibody while C & E have the coresponding natural antibodies, though weak & found infrequently. Rhesus Blood Group System : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 19 Rhesus Blood Group System A single transfusion of + ve blood to a – ve person has a 50% chance of forming anti Rh D antibodies (IgG)
Anti Rh antibodies are of three categories-
1st order – saline / bivalent / complete antibodies
2nd order - albumin active / univalent / incomplete antibodies
3rd order – atypical / antiglobulin active / incomplete antibodies Pathogenesis Of Rh Iso-immunisation : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 20 Pathogenesis Of Rh Iso-immunisation Rh Negative Women Man Rh positive (Homo/Hetero) Fetus Rh Neg Fetus No problem Rh positive Fetus Rh+ve R.B.C.s enter Maternal circulation Mother previously sensitized Secondary immune response ? Iso-antibody (IgG) Non sensitized Mother Primary immune response Fetus unaffected, 1st Baby usually escapes. Mother gets sensitised? Fetus Haemolysis ? Pathogenesis Of Rh Iso-immunisation : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 21 Pathogenesis Of Rh Iso-immunisation Chances of T.P.H/F.M.H. are only 5% in 1st trimester but 47% in 3rd trimester, many conditions can increase the risk.
Chances of primary sensitization during 1st pregnancy is only 1-2%, but 10 to 15% of patients may become sensitized after delivery.
ABO incompatibility and Rh non-responder status may protect.
Amount of antibodies that enter the fetal circulation will determine the degree of haemolysis Pathology Of Iso-immunisation : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 22 Pathology Of Iso-immunisation HAEMOLYSIS IN UTERO AFTER BIRTH BILLIRUBIN ANAEMIA MAT. LIV NO EFFECT HEPATIC ERYTHROPOESIS & DYSFUNCTION PORTAL & UMBILICAL VEIN HYPERTNSION, HEART FAILURE BIRTH OF AN AFFECTED INFANT - Wide spectrum of presentations. Rapid deterioration of the infant after birth. May contiune for few days to few months. Chance of delayed anaemia at 6-8 weeks probably due to persistance of anti Rh antibodies. Jaundice Kernicterus Hepatic Failure DEATH ERYTHROBLASTOSIS FETALIS IUD Prevention of Rh Incompatibility : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 23 Prevention of Rh Incompatibility Premarital counseling? Ambitious?
Proper matching of blood particularly in women before childbearing.
Blood grouping must for every woman, before 1st pregnancy.
Rh+ve Blood transfusion- 300mcg Immunoglobulin (minimum).
Proper management of unsensitised Rh negative pregnancies. Management of Unsensitised Pregnancy : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 24 Management of Unsensitised Pregnancy Blood typing at 1st visit, If negative husband’s typing. If husband is also negative then no treatment
If husband is positive, if possible, Homo/Hetero?
Do Indirect Coomb’s test of mother –
Repeat ICT at 28 weeks – Negative- ICT at 35 weeks - Negative- Observe
Positive Sensitised - 300mcg Rh immunoglobulin Management of Unsensitised Pregnancy : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 25 Management of Unsensitised Pregnancy In Abortion, Ectopic, CVS-
Pregnancy < 12 weeks- 50mcg Anti D
Pregnancy >12 weeks- 300mcg Anti D
APH, IUD, Amniocentesis, Abdominal trauma, Foetal-maternal hemorrhage -300mcg Anti D
At birth- cord blood for ABO & Rh typing
Baby Rh negative – Be happy Management of Unsensitised Pregnancy : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 26 Management of Unsensitised Pregnancy If Rh positive- Test mother’s blood for ICT & Infant’s for DCT
Negative or weakly reactive- 300mcg immunoglobulin
Positive – Sensitised–Hb & Bilirubin Estimation of the infant -Treat the infant
?Prophylactic Anti D administration during antenatal period to all negative mothers at 28weeks and again at 34 / 36 weeks. Management of Sensitized Pregnancy : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 27 Management of Sensitized Pregnancy Causes of sensitization-
Misinterpretation of maternal Rh type
Rh +ve blood transfusion
Unprotected preg. & labour
Inadequate dose / improper use of IgG on previous occasions
Immunization to cross-reacting antigen Management of Sensitized Pregnancy : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 28 Management of Sensitized Pregnancy Careful planning during antepartum, intrapartum & neonatal period
Father’s blood type & Rh antigen status
Knowledge of maternal antibody titer to the specific antigen
Intrauterine foetal monitoring with repeated ultrasound examination, cordocetesis / amniocentesis Management of Sensitized Pregnancy : 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 29 Management of Sensitized Pregnancy Fetus Rh Negative: - Observation
Fetus Rh Positive: -
Intrauterine transfusion of ‘Rh Neg’ blood as indicated
Timely delivery any time after 32 weeks
Management of the infant up to 8 weeks
In cases of severely sensitized women, consider medical termination of pregnancy and sterilization . Slide 30: 15th Agust, 2002 ABO & Rh Isoimmunisation - Prof.S.N.Panda 30 THANK YOU