| ID | 358 |
|---|---|
| Name | Rh. INCOMPATIBILITY |
| Cause | |
| Signs Symptoms | |
| Diagnosis | Diagnosis: Prenatal diagnosis- 1. History of pregnancies- - previous incidence - history of exhange transfusion - any illegitimate pregnancy 2. Blood grouping of both parents. 3. Maternal anti-body titre (by amniocentesis)- titre dilution 1:64 or more is significant; if less than this is in significant. 4. Foetal cell score (of maternal blood). 5. Indirect coomb’s tesl (mother)- usually +ve. 6. Optical density tesl (bilirubin cone, of amniotic fluid). 1. CordHb. = 15 gm/dl 2. Cord bilirubin = 3-5 mg/dl; but it (unconjugated bilirubin) rapidly rises lo a high level in Ihe first 6 hr. of life. 3. Reticulocyle count = 10% (very significanl). 4. Nucleated red cells =10%/100WBC 5. R. B. C. fragmentation - present. 6. Direct coomb’s test (baby) ‘+ve’. (in almost cases it is +ve, but in a few cases may be ‘-ve’, because of very low titre, or very high litre leading lo RBCs are heavily coated with antibody, so testing antibody can nol combine). 7. Indirecl coomb’s test (baby) ‘+ve’. 8. Indirect coomb’s test (mother)‘+ve’. |
| Investigations | |
| Management | Management: See below under ABO incompatibility. |
| Introduction | The Rh. antigenic determinants that are genetically transmitted from each parent & are responsible for Rh. blood grouping of an individual are C.c, D.d, Ee. Each factor can elicite a specific antibody response under suitable conditions, but significant disease is associated primarily with “D” antigen (about 90%). The remaining are due to C & E. When any of big D, C or E is present in the genetic pattern of blood grouping is Rh+ve. It may be- 1. Homozygous positive i.e both parents contributing positive determinants e.g (cDE, cDE), (CDe, cDE) etc. 2. Heterozygous positive e.g (cDE, cde). Incidence of Rh. incompatibility: If mother is ‘-ve’ & foetus is ‘+ve’ although there is chance of sensitization in all the pregnancies, but practically only 4-6% become sensitized & produce antibody. This is because- 1. Only 20% of all pregnancies, there is bleeding & foetomaternal transfusion occur. And, 2. Only 20% of this 20% foetomaternal transmission, there is sensitization and antibody production (because there is low antibody litre in most cases in the mother, which practically do not cause sensitization or incompatibility). Thus the affected pregnancies are only 4% (20% x 20%). |
| History | |
| Etiology | |
| Clinical Features | Clinical feature: In Rh incompatibility, there may be “Hydrops Foetalis” which frequently results in death in utero or shortly after birth (it may also occur from other causes). In live births- 1. May be mild hemolysis (15% of cases) to severe hemolysis & anemia. 2. Progressive Jaundice- usually evident in the first day of life 3. Severe anemia results in- - progressive pallor - signs of cardiac decompensation (hepatosplenomegaly & respiratory distress). 4. Birth asphyxia- due to pulm. oedema or pleural effusion. 5. There may be a great risk of developing kemicterus in rapidly progressing cases. 6. Hypoglycemia- frequently associated. 7. Peteche, purpura, & thrombocytopenia may also be found in severe cases |
| Preventions | |
| Treatment | |
| Complications | |
| Prognosis | |
| Types | |
| Classification | |
| Observation | |
| Pathology | Pathogenesis: When Rh+Ve blood (of foetus) is transfused into an Rh-ve mother by foetomaternal transfusion, during pregnancy, with spontaneous or induced abortion or at delivery antibody formation against “D” antigen may be induced in the maternal blood. Only 0.25 ml blood is enough to sensitize the mother & it is maximum with 0.4 ml of blood & is about 20%; the sensitization almost remains constant (i.e around 20%), if there is transfusion of even more amount of blood. If once sensitization (immunization) has occured, initially a rise of antibody in the 195 (IgM) gamma globulin fraction occurs, which later on replaced by 75 (IgG) antibody. The latter readily crosses the placenta, causing hemolytic manifestations. Hemolytic disease rarely occurs during a first pregnancy, since transfusion of Rh.+ve foetal blood into an Rh-ve mother usually occur at the terminal period of pregnancy or at delivery. So it is too late for the mother to become sensitized (immunized) to transmit antibody to the infant before delivery. As the mother is already been sensitized in the subsequent pregnancies, considerably a smaller doses of antigen (+ve foetal blood) can stimulate an increase in antibody titre. As mother is sensitized the infant is likely to have hemolytic disease, there is a tendency for the severity of the illness to worsen with successive pregnancies. The possibility that the first affected infant after sensitization may represent the end of the mother’s child bearing potential for Rh+ve infants & this argues urgently for the prevention of sensitization wherever is possible. Such prevention consists of injection anti-D gamma globulin (Rho Gam.) into the mother immediately within 72 hours following the delivery of each Rh+ve infant. |
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