Red Cell Iso-immunisation Flashcards
What are iso-antibody/allo-antibodies?
Ab against ag that the mother doesn’t have
What are the common maternal auto-antibody?
Thyroid auto-immune disease
Connective tissue diseases - SLE, Sjogren’s
How does Sjogren’s present in the foetus?
Congenital heart block and cardiomyopathy
What are the iso-ab?
Red cell iso-immunisation
Perinatal allo-immune thrombocytopenia
Perinatal allo-immune neutropenia
Where does spontaneous haemorrhage occur in foetuses with thrombocytopenia?
Intracranial
GI
How does the foetus present with allo-immune neutropenia? How do you treat it?
Serious infection after birth
Abx, IVIg
What are the harmful red cell antigens? What are the harmless?
Rhesus (C/c, D/d, E/e)
Kell, Kidd, Duffy
MNS
ABO
Lewis
P
What are the consequences of red cell haemolysis?
Mild - mild jaundice
Moderate - Severe jaundice, mild anaemia
Severe - severe anaemia > cardiac failure aka hydrops, FDIU
How do you predict the severity of the red cell haemolysis?
Maternal titre of antibody (greater than 512)
How does mother get exposed to Ag?
Blood transfusion (establishes the ab response on the first occasion) Feto-maternal haemorrhage
When does feto-maternal haemorrhage occur?
Bleeding - abortion, miscarriage, ectopic, APH
Trauma - CVS, amniocentesis, version, MVA
Spontaneous
During pregnancy, particularly delivery
How do you prevent maternal ab response forming?
Prophylactic anti-D
How do you determine the D status of the foetal? When do you do it?
Free fetal DNA from maternal blood
WHen dad is heterozygous for D
How do you Mx low risk?
Antibody titre at each visit
Delivery at 38 weeks
How do you mx moderate risk?
Antibody titre at each visit
US MCA flow for anaemia from 20 weeks
CTG from 32 weeks are MCA doppler is less reliable
Delivery at 38 weeks
How do you mx high risk?
US screening for 17 weeks
Foetal blood sampling
Intrauterine transfusion
How do you know if anti red cell antibodies are present?
All pregnancies at screened at first antenatal visit and negatives are again screened at 28 weeks prior to anti-D administration
How much of your blood volume can you lose and survive?
30%
What is the most sensitive measure of hypovolaemia in young people?
Postural hypotension
How do you prevent development anti-D in mum when the foetus has it?
Give passive anti-D ab at times of sensitisation - bleeding, trauma, routine at 28 and 34 weeks.
Within 72 hours of event
What isotypes of antibodies cross the placenta?
IgG
Not IgM
How much anti-D is given at exposure events?
Before 12 weeks - 250IU
After 12 - 650IU or more depending on level of exposure
