RH ISOIMMUNIZATION BWIRE2.pptx

rhesus isoimmunization

1. Rhesus Isoimmunization Presenter: Dr. Bwire Innocent - Resident Obsgyn -KIU Mentor: Dr. Kato Paul - Obstetrician/Gynaecologist-HRRH

2. Outline Introduction to ABO And Rhesus Blood Group System Epidemiology Causes Grandmother effect Pathophysiology Investigations management Prevention

3. Introduction Isoimmunization / alloimmunization : Production of antibodies in response to an antigen derived from another individual of the same species Rhesus Isoimmunization Maternal antibody production in response to fetal red blood cell Rh antigen which occurs when mother Rh negative ,fetus Rh postive . Sensibilized : producing detectable antibodies only in a subsequent pregnancy (Bowman, 1985).

4. ABO blood group system 4 blood types (A, B, AB & O) additionally classified according to the presence or absence of Rh factor

5. The Rhesus Factor A group of antigens that may or may not be present on the surface of the red blood cells. the m ost common Include C,c, D,d, e and E antigens The 2 responsible genes: RHD and RHCE are located on the short arm of x-some 1 and are inherited together, independent of other BG genes. D antigen is the most immunogenic and determines Rh positivity i.e Rh positive , those who lack the D antigen are Rh negative . Fetal Rh-antigen are present by 38th day after conception.

6. The Rhesus Factor Rh alleles : Cc, Dd and Ee . D antigen, the most potent, its presence or absence denotes an individual to be Rh + ve or – ve . DD homozygous, Dd -heterozygous, dd - negative.

7. The Rhesus Factor H eterozygous + father: Dd , Homozygous+ father: DD , Mother dd

8. Abo Incompatibility ABO incompatibility describes an immune reaction that occurs in the body if two blood samples of different, incompatible ABO types are mixed together, when these RBC act as antigen & an immune response is triggered. It affects newborns whose mothers are blood type O, and who have a baby with type A, B or AB. Other blood group systems; K idd, D iego, K ell , MNS, D uffy , L ewis , Scianna , D ombrock , C olton, G erbich , Lutheran, I

9. Rhesus Incompatibility

10. Epidemiology It is more frequent among Caucasians descent (15-17%), Africans (4-8%), Asian descent (0.1-0.3%). ( Bhutani et al 2013) Prevalence in Uganda is not known, found to be 2.2% in south western Uganda ( Natukunda et al 2011 ) Without anti-D immune globulin prophylaxis, a D-negative woman delivered of a D-positive, ABO-compatible newborn has a 16% likelihood of developing alloimmunization . 2% will become sensitized by the time of delivery , 7 % by 6 months postpartum , and the remaining 7% will be “ sensibilized ”( Boweman , 1985)

11. Thus, affection of the baby due to Rh incompatibility is low considering the increased number of Rh+ babies delivered to Rh- ve mothers . Insufficient placental transfer of fetal antigens or maternal antibodies . Inborn inability to respond to the Rh antigen stimulus . Immunological non-responder —as found in 30% of Rh-negative women . ABO incompatibility has a protective effect against the development of Rh sensitization. significant if mother is type O, father is type A, B or AB Variable antigenic stimulus of the D antigen which depends on the Rh genotype of the fetal blood, e.g. CDe / cde genotype . Volume of fetal blood entering into the maternal circulation (0.1 mL is considered as critical sensitizing volume ).

12. Early pregnancy loss    abortion- elective or spont . molar pregnancy Ectopic pregnancy Fetal death (any trimester) Procedures Fetal blood sampling, CVS, Amniocentesis Cesarean Section/ vaginal delivery blood transfusion /bone marrow transplants injections with contaminated needles Idiopathic : ? Vanishing twin, grandmother theory Other   Idiopathic   Maternal trauma/APH   Manual placental removal   External version Causes of Fetomaternal Hemorrhage that May Incite Rh Isoimmunization

13. The Grandmother Effect In virtually all pregnancies, small amounts of mat. blood enter the fetal circulation. PCR has been used to identify mat D+ve DNA in peripheral blood from preterm and full-term D- ve newborns (Lazar, 2006 ). Thus , it’s possible for a RhD - female fetus exposed to mat. rhD + red cells to develop sensitization. When such an individual reaches adulthood , she may produce anti-D antibodies even before or early in her 1 st pregnancy . mechanism called the grandmother effect or theory bse the fetus in the current pregnancy is jeopardized by mat. ab that were initially provoked by his or her grandmother’s erythrocytes .

14. Pathophysiology There is normally no mixing of fetal & maternal blood during pregnancy. When the placenta begins to separate & the chorionic villi tear, the risk of feto -maternal transfusion is increased. Rh antigens of the fetal red cells (0.1ml) stimulate the prodn of maternal antibodies(become detectable after 6 months) The 1 st encounter may not result in Ig M but no sensitization, on 2 nd encounter Ig G are produced and these cross the placenta

15. Pathophysiology maternal IgG crosses the placenta barrier & enters into fetal circulation while IgM does not cross. Once formed the antibodies are permanent. If the fetus is Rh positive, the antibody becomes attached to the antigen sites on the surface of the erythrocytes. The affected cells are rapidly removed from the circulation by the RES resulting in fetal anemia. Hyperplasia of the placental tissue occurs in an effort to increase the transfer of oxygen but the available fetal red cells

16. Fetal effects There is no risk 1st trimester abortion in RH Isoimmunization unless a/w other congenital anomalies Effects of RH Isoimmunization is not evident till second trimester of pregnancy only after 2nd trimester the reticuloendothelial system of fetus is developed and RH antigens are formed in utero It has been found that the amount of FMH is very minute (around 0.03 mL ) during 1st and 2nd trimester however it may be as high as 25 mL during 3rd trimester ( Puangsricharern 2007 : Bhatnagar 1980)

17. Fetal effects Destruction of fetal RBC’s cause fetal anaemia which is continuous during intrauterine life . Due to anemia, the fetal growth is retarded Erythroblastosis fetalis . Overproduction of immature fetal and neonatal red cells, now called Hemolytic disease of the fetus and newborn(HDFN) Hydrops fetalis : abnormal collection of fluid in more than one area of the fetal body is termed hydrops fetalis (scalp edema, pleural effusion , pericardial effusion, ascites, and skin edema). Buddha’ sign on ultrasound. tissue hypoxia and acidosis eventually lead to intra uterine fetal death .

18. Neonatal Effects Congenital hemolytic anemia: slow hemolysis , the anemia develops slowly within 1 st few weeks of life, the jaundice is not usually evident. Hemolysis continues up to 6 weeks due to antibody presence Hyperbilirubinemia , if timely actions are not taken the hyperbilirubinemia results in deposition of bilirubin in the basal cerebral ganglia leading to kernicterus . Due to relative immaturity of function of the liver Icterus gravid neonatorum . The fetus is born alive without jaundice but develops it within 24 h . Progressive anemia can lead to congestive cardiac failure and death

19. Maternal effects There is increased incidence of: Preeclampsia; Polyhydramnios; Big size baby with its hazards; Hypofibrinogenemia -prolonged retention of dead fetus in uterus; Postpartum hemorrhage - big placenta and blood coagulopathy; “maternal syndrome”- generalized edema, proteinuria and pruritus due to cholestasis.

20. Investigations Blood grouping and Rhesus typing Indirect Combs test (ICT): maternal antibody screen Paternal zygosity testing (PCR) Cell free fetal DNA testing Kleihauer-Betke test: amount of fetal blood in maternal circulation. amnionic fluid Spectrophotometry: also known as the ΔOD450 test, is no longer recommended (SMFM, 2015) Fetal blood sampling Cord blood examn : ABO , Rh, DCT, Hb and Bilirubin

21. If severe fetal anemia, a sinusoidal heart rate pattern may develop

22. Direct Coombs’ Test used to detect these antibodies or complement proteins that are bound to the surface of RBC. A blood sample is taken & the RBCs are washed & then incubated with antihuman globulin[also known as coombs’ reagent]. If this produces agglutination [clumping together] of RBCs, The Direct Coombs’ Test Is Positive.

23. Indirect Coombs’ Test It detects antibodies against RBCs that are present unbound in the patient’s serum. In this case serum is extracted from the blood sample taken from the patient. Then the serum is incubated with the RBC of known reference values from other patient blood samples. If this produces agglutination of RBCs, The Indirect Coombs’ Test Is Positive.

24. KB test Fetal red cells in the maternal circulation can be identified by use of the acid elution principle first described by Kleihauer , Brown , and Betke Fetal erythrocytes contain HbF , which is more resistant to acid elution than HbA . After exposure to acid, only fetal hemoglobin remains. Fetal red cells can then be identified by uptake of a special stain and quantified on a peripheral smear If there are 80 fetal RBCs in 50 low power fields in mat peripheral blood films, it rep. a transplacental hemorrhage to the extent of 4 mL of fetal blood.

25. Diagnosis The essentials of diagnosis are: 1. The mother must be Rh negative. 2. Presence of maternal Rh antibodies as shown by a positive indirect coombs’ test on mother’s blood . 3. Maternal antibody titre posing risk to fetus. 4. History of birth of previous affected baby. 5. Fetal cord blood shows low level of Hb at birth & raised bilirubin

26. Management Fetal Risk A ssessment maternal Antibody titer surveillance Ultrasound monitoring of the fetal MCA PSV if a critical antibody titer is reached Delivery timing and mode

27. Critical titer The critical titer is the level at which significant fetal anemia could potentially develop. This may be different for each antibody, is determined individually by each laboratory, and usually ranges between 1:8 and 1:32. the critical titer for anti-D antibodies is 1:16, a titer ≥1:16 indicates the possibility of severe hemolytic disease. In any pregnancy in which the antibody titer has reached a critical value, there is no benefit to repeating the titer.

28. Management of Rh- ve Non-sensitized mother Initial evaluation of alloimmunization risk with blood group and Rh factor , mat antibody screening with indirect coombs test at booking visit Monthly ICT till delivery , if positive manage as sensitized At 28 weeks give prophylactic 300-μ g of anti-D and within 72 hrs after delivery if rhesus positive newborn If immune anti-D ab is detected, prophylaxis is no longer necessary

29. Management Of rh-ve Sensitized Mother S ensitization IS by the detection of Rh antibodies in mat, circulation using ICT . If alloimmunization is detected and the titer is below the critical value, the titer is generally repeated every 4 weeks for the duration of the pregnancy (ACOG, 2019a). Anti-D antibody titres determined and if titre < 4IU/ml is unlikely to produce severe fetal disease, if > 4 iu /ml but < 15 iu /ml correlates with a moderate risk of HDFN , if > 15 iu /ml can cause severe HDFN. After the 1 st affected pregnancy, the ability to predict fetal anemia from the mat. anti-D antibody titers is lost and now these pregnancies shd be monitored by MCA-PSV

30. When to administer RHOGAM? It binds to fetal RBCs and prevents stimulation of maternal immune system . It should be given at 28 wks to all unsensitized Rh- ve mother and postpartum within 72 hours if the baby’s Blood group is Rh positive. In case, where the specified time limit is over (>72hour) She may be given up to 28 days after delivery to avoid sensitization. One 300-μg dose is given for each 15 mL of fetal red cells or 30 mL of fetal whole blood to be neutralized. 10 μ g of anti- D should be given for every additional 0.5 mL of fetal RBCs in maternal circulation.

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32. fetal transfusion (intra-uterine transfusion). Fetal blood sampling is generally performed if the MCA PSV exceeds the threshold for severe anemia, with plan for concurrent IUT as needed. If the MCA PSV exceeds 1.5 MoM or if hydrops develops or fetal Hct <30% or the Hb is at least 2 g/dl below the mean for normal fetuses of corresponding GA. fresh O-negative doubly packed cells is given to the fetus by intravascular or intraperitoneal route. The volume transfused = (Gest age – 20) × 10 mL Fetal transfusion is typically performed prior to 34 to 35 WOG . Later in gestation, the benefits of transfusion may be outweighed by the risks of delaying delivery..

33. Obstetric management Aim is to carry beyond 34 weeks. Mildly affected fetus – May wait till term and for spontaneous onset of labour . Moderately affected fetus – either vaginally or by LSCS before term. Severely affected fetus – LSCS is preferred when fetal parameters poor Care at delivery: Close monitoring through out the first stage, Clamp the cord immediately, Gentle handling of the uterus, Cord blood is collected for neonatal group and type, Hb, haematocrit , bilirubin and direct Coombs Avoid the following : Uterine massage, Manual removal of placenta , Ergometrine

34. Postnatal Management The neonates may be born with anemia, hepato-spleenomegaly & ascites and rapidly develop hyperbilirubinemia. These infants are hypo- coagulable & have a tendency of developing hypoglycemia. The presence of positive DCT is sufficient to confirm the diagnosis in an Rh positive neonate born to a sensitized Rh negative women.

35. Treatment of neonatal anemia In those infants who exhibit only anemia, fresh packed red cells are given to correct this defect. The management of hydrops fetalis which is the several form of the disorder is usually done by the rapid correction of anemia by small exchange transfusion 20 to 40 ml/kg body wt raises the hematocrit sufficiently.

36. Treatment Of Neonatal Jaundice. Phototherapy exposure of neonates to light with wave length of 420-470mm results in addition of bilirubin & conversion to products that are water soluble, are not neurotoxic and which can be excreted via stool and urine. It takes 12-24 hrs to be effective.

37. Exchange transfusion: Helps by removing unconjugated bilirubin & Rh positive cells coated with antibodies. Traditionally double volume exchange transfusion done via umbilical vein using group specific negative blood cross matched with mothers serum effectively. Indications: Rh-positive with direct Coombs’ test positive babies having: (i) Cord blood bilirubin level > 4 mg/dl and hemoglobin level is < 11 gm/dl. (ii) Rising rate of bilirubin over 1 mg/dl/hour despite phototherapy. (iii) Total bilirubin level is 20 mg/dl or more.

38. Prevention Of Maternal Isoimmunization There are 3 ways of preventing a women from producing rhesus antibodies. Avoiding transfusion of Rh positive blood. - avoids sensitization Prevention of avoidable feto -maternal transfusion- avoid transplacental amniocentesis Administration of ANTI D immunoglobulin

39. Thank you for listening queries, supplements are welcome References Williams Obstetrics, 26 th edition, 2022 RCOG, The Management of Women with Red Cell Antibodies during Pregnancy. Green-top Guideline No. 65, May 2014 . DC Dutta’s, Text book of obstetrics,8 th ed, 2015 Smart Study Series: Obstetrics and Gynecology, 3/e Bhojani Up To Date 2023 Agarwal, K., Rana, A. & Ravi, A.K. Treatment and Prevention of Rh Isoimmunization .(2014). https :// doi.org/10.1007/s40556-014-0013-z Gabbes obs / self asssesments obstetrics, Holland/brews Manuel of obstetrics