Red Cell Iso-immunisation

Question 1

What are iso-antibody/allo-antibodies?

Answer 1

Ab against ag that the mother doesn’t have

Question 2

What are the common maternal auto-antibody?

Answer 2

Thyroid auto-immune disease

Connective tissue diseases - SLE, Sjogren’s

Question 3

How does Sjogren’s present in the foetus?

Answer 3

Congenital heart block and cardiomyopathy

Question 4

What are the iso-ab?

Answer 4

Red cell iso-immunisation
Perinatal allo-immune thrombocytopenia
Perinatal allo-immune neutropenia

Question 5

Where does spontaneous haemorrhage occur in foetuses with thrombocytopenia?

Answer 5

Intracranial

GI

Question 6

How does the foetus present with allo-immune neutropenia? How do you treat it?

Answer 6

Serious infection after birth

Abx, IVIg

Question 7

What are the harmful red cell antigens? What are the harmless?

Answer 7

Rhesus (C/c, D/d, E/e)
Kell, Kidd, Duffy
MNS

ABO
Lewis
P

Question 8

What are the consequences of red cell haemolysis?

Answer 8

Mild - mild jaundice

Moderate - Severe jaundice, mild anaemia

Severe - severe anaemia > cardiac failure aka hydrops, FDIU

Question 9

How do you predict the severity of the red cell haemolysis?

Answer 9

Maternal titre of antibody (greater than 512)

Question 10

How does mother get exposed to Ag?

Answer 10

Blood transfusion (establishes the ab response on the first occasion)
Feto-maternal haemorrhage

Question 11

When does feto-maternal haemorrhage occur?

Answer 11

Bleeding - abortion, miscarriage, ectopic, APH
Trauma - CVS, amniocentesis, version, MVA
Spontaneous
During pregnancy, particularly delivery

Question 12

How do you prevent maternal ab response forming?

Answer 12

Prophylactic anti-D

Question 13

How do you determine the D status of the foetal? When do you do it?

Answer 13

Free fetal DNA from maternal blood

WHen dad is heterozygous for D

Question 14

How do you Mx low risk?

Answer 14

Antibody titre at each visit

Delivery at 38 weeks

Question 15

How do you mx moderate risk?

Answer 15

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

Question 16

How do you mx high risk?

Answer 16

US screening for 17 weeks
Foetal blood sampling
Intrauterine transfusion

Question 17

How do you know if anti red cell antibodies are present?

Answer 17

All pregnancies at screened at first antenatal visit and negatives are again screened at 28 weeks prior to anti-D administration

Question 18

How much of your blood volume can you lose and survive?

Answer 18

30%

Question 19

What is the most sensitive measure of hypovolaemia in young people?

Answer 19

Postural hypotension

Question 20

How do you prevent development anti-D in mum when the foetus has it?

Answer 20

Give passive anti-D ab at times of sensitisation - bleeding, trauma, routine at 28 and 34 weeks.
Within 72 hours of event

Question 21

What isotypes of antibodies cross the placenta?

Answer 21

IgG

Not IgM

Question 22

How much anti-D is given at exposure events?

Answer 22

Before 12 weeks - 250IU

After 12 - 650IU or more depending on level of exposure