L9-11: Rh Isoimmunization, ABO Incompatability & Fetal Hydrops Flashcards
def of Rh Isoimmunization
Synonyms of Rh Isoimmunization
- Erythroblastosis fetalis
- Hemolytic disease of newborn
Rh Isoimmunization
- Rh Factor
Rh Genes
Most Important Rh gene
D gene β Rh +ve.
Rh +ve person
homozygous (DD) or heterozygous (Dd).
Rh -ve person
only homozygous (dd).
Rh Antigens
5 Ags (C, D, E, c, e) on surface of RBCs (no lower d Ag).
Incidence of Rh Isoimmunization
Incidence of Rh Isoimmunization
- Rh -ve persons
Incidence of Rh Isoimmunization
- Rh Isoimmunization
Incidence of Rh Isoimmunization
- the great difference () incidence of Rh -ve persons & incidence of Rh isoimmunization is explained by
Etiology of Rh Isoimmunization
Etiology of Rh Isoimmunization
- Any contact () Rh + ve fetal blood & maternal circulation
Etiology of Rh Isoimmunization
- Blood transfusion of Rh +ve blood to Rh -ve female at any age
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pathogenesis of Rh Isoimmunization
pathogenesis of Rh Isoimmunization
- Which Antigen?
- 95% of cases of isoimmunization are caused by maternal sensitization against Rh Ag D however, other Rh Ags (C & E) may rarely initiate isoimmunization
- Once Rh isoimmunization has been initiated, the individual produces large amounts of Abs (2ry response) in response to small amounts of fetal blood.
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pathogenesis of Rh Isoimmunization
- Amount of Blood Needed
As little as 0.25 ml of fetal Rh +ve cells can lead to isoimmunization.
pathogenesis of Rh Isoimmunization
- Type of Abs
- Initially, anti-Rh IgM Abs are formed (it has large MW so, donβt cross placenta & donβt cause hemolysis of fetal RBCs).
- This is followed by the formation of anti-Rh IgG Abs that cross placenta β destruction of fetal RBCs.
CP of Rh Isoimmunization
CP of Rh Isoimmunization
- Degrees
- Congenital hemolytic anemia: Mildest form
- Icterus gravis neonatorum: Commonest form
- Fetal hydrops: Rarest & most severe form
CP of Rh Isoimmunization
- Congenital hemolytic anemia
CP of Rh Isoimmunization
- Icterus gravis neonatorum
CP of Rh Isoimmunization
- Fetal Hydrops
Dx of Rh Isoimmunziation
- Hx
- Rh Typing
- Indirect Coombs Test
- US
- X-Ray
- Spectrophotometric analysis of AF
- Fetal blood sampling
- Neonatal blood sampling
Dx of Rh Isoimmunziation
- Hx
1) Past history: Previous blood transfusion.
2) Obstetric history: Previous affected baby or IUFD which may be recurrent.
Dx of Rh Isoimmunziation
- Rh Typing
Dx of Rh Isoimmunziation
- Indirect Coombs Test
Indirect Coombs test in Rh Isoimmunziation
- Aim
Detection of presence of anti-Rh Abs in maternal serum & determination of level of these Abs.
Indirect Coombs test in Rh Isoimmunziation
- Technique
Dx of Rh Isoimmunziation
- US
Dx of Rh Isoimmunziation
- X-Ray
Dx of Rh Isoimmunziation
- Spectrophotometric analysis of AF
Spectrophotometric analysis of AF in Rh Isoimmunization
- Aim
- Determination of AF bilirubin level that reflects degree of fetal RBCs hemolysis.
Spectrophotometric analysis of AF in Rh Isoimmunization
- Indications
Spectrophotometric analysis of AF in Rh Isoimmunization
- Procedure
- Amniocentesis & sample of 5-10 ml of AF is taken.
- Protect specimen from light as it decolorizes bilirubin.
- Spectrophotometric analysis of AF