Identification and management of fetal anaemia: a practical guide TOG 2021

Question 1

Most common cause fetal anaemia

Answer 1

antibody-mediated destruction of red blood cells via maternal alloimmunisation

Question 2

What should fetal Hb at term? Dx severe fetal anaemia?

Answer 2

Term 150

Severe - 70g/l below expected for gratin or <0.55 median

Question 3

How common HDFN

Answer 3

1 in 300-600 births

Question 4

What is now the most common red cell antibody to cause of HDFN?

Answer 4

Now Anti-E

Used to be anti-D but immunoprophylaxsis has reduced this to 2%

Question 5

How often should alloimmunised women have bloods checked

Answer 5

4 weekly until 28 weeks then 2 weekly.

Increase risk of above threshold;ds - refer to FMU

Question 6

What infections can cause anaemia?

Answer 6

Parvovirus B19
CMV

Question 7

Risk of transmission of parvovirus to fetus based on GA

Answer 7

<15 weeks: 15%
15-20 weeks: 25%
Term: 70%

Question 8

Risk of fetal loss if B19 infection < 20 weeks

Answer 8

13%

Question 9

Other causes of fetal anaemia

Answer 9

Disorders of erythropoiesis - Aplastic anaemia, Alpha that, genetic RBC production - Fanconi anaemia. Haemolytic - G6PD.

Vascular tumours- sacrococcygeal tumour

FM haemorrhage

MC Twins - TAPs

Question 10

How to identify anaemia antenatally?

Answer 10

Maternal blood serum anti-bodies
USS feature hydrops
Direct bloods sampling
MCA-PCV >1.5

Question 11

Risk of miscarriage with direct fetal blood sampling

Answer 11

2%

Question 12

Possible in utero treatments

Answer 12

Intrauterine transfusion
Medical treatments - IVIF (block transport of alloautoantibodies), material plasma exchange

Question 13

How long can maternal antibodies remain in babies circulation?

Answer 13

6 months

Treated with phototherapy, exchange transfuse