Rh Incompatibility in Pregnancy PDF

RH Isoimmunizatio n Dr.Banav Najeeb Objective What is Rhesus antigen? What is Rh incompatibility? Pathophysiology of Rh incompatibility The effect of Rh incompatibility Diagnosis of Rh incompatibility Prevention of Rh incompatibility Management of affected cases of Rh incompatibility Rhes...

RH Isoimmunizatio n Dr.Banav Najeeb Objective What is Rhesus antigen? What is Rh incompatibility? Pathophysiology of Rh incompatibility The effect of Rh incompatibility Diagnosis of Rh incompatibility Prevention of Rh incompatibility Management of affected cases of Rh incompatibility Rhesus antigen The Rh(Rhesus) factor is a specific protein found on the surface of red blood cells. If this protein present it is Rh +, if not is Rh – A positive or negative symbol after blood type indicates Rh factor. For example, “blood type: AB+” It is inherited as autosomal dominant. There are 5 Resus antigen, (D, C, c, E, e) but the positive and negative Rh depend D (D is the most immunogenic) It Rh negative account about 15% of population. Rh-negativity occurs more frequently among those of Caucasian compared to those of African or Asian Pathophysiology When a Rh-negative mother is exposed to the Rh D antigen, the D antigen is perceived as a foreign threat similar to how bacteria and viruses are perceived. This leads to a series of activations of immunogenic pathways that culminates in the production of anti-D antibodies. These antibodies can freely cross the placenta to the fetus, bind to the D antigen present on the erythrocytes of Rh- positive fetuses to further activate immunologic pathways that lead to the hemolysis of the fetal In the first antenatal visit the blood group and Rhesus type of the women should be identified. If woman is Rh-negative, the partner’s Rh must be tested. If the partner is also Rh-negative, there is no reason to worry about. If the partner is Rh-positive, there is a chance of getting a Rh positive fetus(100%) in homozygous and 50% in heterozyhous. If the partner Rh unknown we should consider the baby as Rh positive for more protection Chances of feto-maternal hemorrhage are only 5% in 1st trimester but 47% in 3rd trimester, Chances of primary sensitization during 1st pregnancy is only 1-2% Amount of antibodies that enter the fetal circulation will determine the degree of haemolysis The clinical presentation of Rhesus (Rh) isoimmunization varies from mild jaundice, anaemia to hydrops fetalis. During pregnancy while the fetus still in the uterus: The bilirubin in the fetal blood will be removed by the placenta to the maternal circulation and part of it go to the liquor. The fetus will be anemic.. If the degree of anemia is sever fetus may die in utero because of heart failure After delivery : The neonate will affected by the degree of the anemia Non fetal exposure to Rh-positive blood Transfusion of incompatible blood Bone marrow transplantation Prevention: Rhesus incompatibility is preventable In unsensitized women: -Rh-immune globulin(Rh Ig) 300 mcg (300 mcg covers 15 ml fetal cells) is given between 28-32 weeks gestation. - If the neonate is found to be Rh-positive after delivery, women should be given Rh Ig within 72 hours of delivery.  Rh Ig immunoprophylaxis It can be applied to Rh-negative mothers who have high-risk of feto-maternal hemorrhage like:  Miscarriage  Ectopic pregnancy  Molar pregnancy  Antepartum hemorrhage  External cephalic version  After prenatal tests and Invasive procedure such as amniocentesis and chorionic villus biopsy  Abdominal trauma  Failure of prophylaxis  Dose too small  Dose too late >72 hours Factors affecting immunization and severity Amount of Antigen ( amount of fetal RBCs) Host factors (Integrity of Maternal Immune Sys) Strength of the antigen..…. (antigenicity) Indirect Coombs test A positive test is a sign of Rh incompatibility (sensitization). This test uses a blood sample of mother to look for the presence of cell-destroying antibodies within the plasma. Kleihauer-Betke (KB) test or flow cytometry Is used to determine the percentage of fetal blood cells in the maternal circulation for the assessment of fetomaternal hemorrhage  Amniocentesis Is an Indirect method to measure the degree of haemolysis of the fetal red blood cells by measuring the Concentration of.bilirubin in the amniotic fluid Amniotic fluid sample taken and sent for Spectrophotometer Where optic density of the fluid changes according to the amount of the bilirubin concentration Increasing of the OD shows worsening of the fetal hemolytic disease Zone I indicates mild disease. Zone II indicates intermediate disease. Fetuses are usually followed by amniocentesis every 1-2 weeks. ZoneIII may require transfusion or delivery Management of Sensitized Patient Maternal antibody titers (serial indirect coombs test) is recommended. Titers are repeated every month until 24 weeks of gestation and repeated more frequently in the third trimester. Fetal DNA testing (If the fetus is antigen negative then no further testing is necessary). Antenatal ultrasound examination will help in assessing the amount of liquor in a suspected polyhyraminos and identify presence of hydrops fetalis Doppler ultrasound measuring ductus venosus blood flow and peak systolic velocity of the fetal middle cerebral artery will useful in assessing the degree of anaemia. Amniocentesis in case of fetal anaemia to measure the amount of bilirubin can be quantitatively measure by spectrophotometer and the results (delta 450) are plotted on a "Liley" curve. Treatment of sensitized patient: Term pregnancy ( mild or Severely affected ) …Deliver Suitability of the place and its facility Experience of the team Type of Delivery Medication Photo therapy Extra uterine Blood exchange After birth: Mild jaundice treated by phototherapy Moderate and sever jaundice treated by exchange blood transfusion Preterm fetus IF blood sample Hb >1g/dL No U / S Scan evidence of Hydropi changes Consider conservative management with regular follow up of fetal and maternal conditions till the fetal lung maturity is assured …. Then deliver Preterm fetus with Zone II or III Transfer to suitable place for Intra uterine therapy Delivery + extra uterine mang. Depned on the GA Dexamethazone to enhance lung maturity Clinical assessments + C T G + U / S Scan + B P Consider repeating the intrauterine Intrauterine blood transfusion For exchange transfusion,  the blood should be less than a week old(fresh),  Rh – and ABO compatabile with both maternal and baby’s tested for CMV and hepatitis viruses Phototherapy for neonatal jaundice in mild disease If the mother is sensitized with high levels of D antibodies, family planning advice should be given, this is very important if the father is homozygous for Rh gene as there is a chance of getting a Rh positive baby is 100% Fetal hydrops What is Hydrops fetalis? What are the types of Hydrops fetalis? Causes of hydrops fetalis Diagnosis of Hydrops fetalis Management of Hydrops fetalis Fetal hydrops Is a life threatening hemolytic anemia which defined as abnormal accumulation of fluid in the fetal soft tissues and body, including ascites, pleural effusion, pericardial effusion, and skin edema. In some patients, it may also be associated with polyhydramnious and placental edema. It is associated with a significant mortality Types of hydrops fetalis: Immune hydrops fetalis (IHF) Non-immune hydrops fetalis (NIHF) The type depends on the cause of the condition. Non-immune hydrops fetalis is now the most common type.  Non-immune hydrops fetalis It occurs when another condition or disease interferes with the baby’s ability to regulate fluid or a pressure differential between the heart and body. ▪Cardiac defect ▪Fetal anemia, including alpha thalasaemia, twin-twin transfusion syndrome and feto-maternal hemorrhage ▪lung defects ▪Genetic cause, including Turner syndrome, triosomy13 and 21 infection like parvo virous B  Diagnosing hydrops fetalis Ultrasound of the unborn baby that shows Large amounts of amniotic fluid(polyhydraminous), Thickened placenta, enlarged liver, spleen, or heart. It may show a fluid buildup around the baby’s abdominal organs, heart, or lungs and ascites. ▪fetal blood sampling for karyotyping, virology, full blood count enzymatic studies and liver function test ▪Doppler ultrasound for MCA ▪amniocentesis, which is the withdrawal of amniotic fluid for further testing ▪fetal echocardiography  Maternal risk: Rapid onset or unusual type of preeclampsia Postpaartum haemorrhage Amniotic fluid embolism  Treatment The treatment of hydrops is based on the following factors: The baby’s overall health Gestational age Extent of the disease  Cause of the hydrops  Treatment of fetal hydrops Supportive measures required including: management of respiratory status management of fluid and electrolyte status. pleural drainage, Chest tubes may need Arrhythmia of fetal heart can be treated by drugs to the mother or fetus  nutrition management  intravascular volume replacement, blood pressure support immune support correction of anemia by intrauterine transfusion After birth, symptoms may include: Pale coloring Severe swelling overall, especially in the baby's belly (abdomen) respiratory distress Enlarged liver and spleen  Prognosis The outlook for hydrops fetalis depends on the underlying condition, but even with treatment the perinatal mortality is >85% in NIHF The risk of death is highest for babies who are diagnosed very early (less than 24 weeks into pregnancy) or who have structural abnormalities, such as a structural heart defect  ABO System & Pregnancy hemolytic diseases of the newborn may be due to ABO incompatibility Fetus inherits one gene from each parent. ABO System & Pregnancy O + O when=the mother Is a haemolytic disease O, o+and baby is A+ or B+ O+A = O or A, O+B = O or B, O + AB = A or B  ABO incompatibility  There is a 20% chance of ABO incompatibility of mother & fetus if feto maternal Hemorrhage occur The risk of stillbirth is not increased  Less than 5% chance of developing noticeable hemolytic disease ( milder forms )  It is more prominent in type A & B infants of type O mothers  Is less sever than Rh incompatibility  antenatal diagnosis Direct Coomb’s antiglobulin test may benegative in ABO haemolytic disease  ABO haemolytic disease is frequently seen in infants of primigravidae  the chance of recurence is 87%. Anti-A & B produced in the mother being natural are IgM molecules & so do not cross placenta & no antenatal treatment is necessary 67% of affected infants will need any treatment Thank you