Haemophilia A and B and pregnancy

Question 1

Which clotting factor is affected in haemophilia A?

Answer 1

Factor 8 VIII

Question 2

Which clotting factor is affected in haemophilia B?

Answer 2

Factor 9 IX

Question 3

What is the mode of inheritance of haemophilia A and B?

Answer 3

X linked recessive

Question 4

Risk of inheritance in female baby of affected male

Answer 4

100% will be carriers

Question 5

Risk of inheritance in male baby with maternal carrier

Answer 5

50% will have the condition

Question 6

What is the definition of severe haemophilia and what are the features?

Answer 6

clotting factor <0.01iu/ml - associated with spontaneous intramuscularly and joint haemorrhage and requiring regular replacement of clotting factors

Question 7

What is the definition of moderate and mild haemophilia and what are the features?

Answer 7

moderate = 0.01-0.05
Mild = 0.06 - 0.4
Higher risk of bleeding with invasive procedures

Question 8

What proportion of babies born with severe haemophilia have no family history and how does this happen?

Answer 8

up to 50% - a sporadic mutation generally occurs in maternal sperm = 90% of these babies will have a mother who is a carrier (but does not know it)

Question 9

What prenatal genetic tests are available?

Answer 9

pre-implantation genetic diagnosis as part of IVF
at 9 weeks - cell free fetal dna for y chromosome
11-13+6 - CVS
15+ amniocentesis
34+ amniocentesis for delivery planning

Question 10

What is the risk of haemophilia A and B for the mother during pregnancy?

Answer 10

Haemophilia A - factor 8 levels rise in pregnancy but still may be abnormal
Haemophilia B - factor 9 levels remain unchanged in pregnancy and therefore may be abnormal
*lyonisation means that carrier mothers may still be at risk of bleeding with procedures + at risk of PPH

Question 11

What is the risk of intracranial and extracranial haemorrhage in an affected male fetus?

Answer 11

ICH - 2.5% (OR of 44)

ECH - 3.7% (OR 8)

Question 12

During pregnancy when should haemophilia factors be measured?

Answer 12

Booking, pre invasive procedure, third trimester

Question 13

What is an acceptable maternal factor level for invasive procedures?

Answer 13

> 0.5 (ideally higher for c/s)

Question 14

In haemophilia A, how can factor levels be increased pre invasive procedure?

Answer 14

DDAVP (synthetic vasopressin) IV
If this doesn’t work then recombinant factor VIII can be given
* aiming for clotting factor level of 1

Question 15

What are the side effects and contraindications of DDAVP?

Answer 15

Side effects - hypotension, flushing, headache, HYPONATRAEMIA (1 litre intake of fluid/24 hours)
contraindications: pre-eclampsia

Question 16

In haemophilia B, how can factor levels be increased pre-invasive procedure?

Answer 16

DDAVP DOES NOT WORK
Give recombinant factor IX (blood test before, after and at 4-5 hours)
Aiming for clotting factor level of 1

Question 17

How should male neonates of haemophilia A and B carriers be delivered?

Answer 17

male affected or unknown status - offer elcs
If vaginal opted - aim for spontaneous, avoid ventouse and rotational/midcavity forceps
If severe/moderate haemophilia avoid FBS and FSE

Question 18

How should female neonates of haemophilia A and B carriers be delivered?

Answer 18

Female A carriers - any MOD acceptable

Female B severe form - consider offering elcs/manage as for males

Question 19

What factor level is required for epidural?

Answer 19

Insertion and removal needs >0.5

Question 20

How should mothers with haem A and B be managed intrapartum?

Answer 20

Optimise clotting factor levels (aiming for >0.5)
Give IV TXA
Active management of 3rd stage

Question 21

How should mothers with haem A and B be managed postpartum?

Answer 21

Active management of 3rd stage
TXA until lochia normal
Maintain clotting factor levels >0.5 for 3 days post SVD adn 5 days post c/s and instrumental

Question 22

How should male neonates with suspected haem A and B be managed?

Answer 22

Cord blood - if positive will need formal blood
Mild cases may not be detected and need repeating at 3-6 months
Avoid im vit K until result - or opt for oral vit K
If severe or trauma - cranial USS/MRI