Haematology 9 - Obstetric haematology

Question 1

What change in Hb concentration occurs in pregnancy and why?

Answer 1

Lower concentration (mild anaemia)
Red cell mass rises 125%
Plasma volume rises 150%
So [Hb] falls

Question 2

What is the most common cause of anaemia in pregnancy?

Answer 2

Physiological rather than a deficiency

Question 3

What change occurs in the neutrophil count in pregnancy?

Answer 3

Physiological fall, particularly towards the end

Question 4

How do platelets change in pregnancy?

Answer 4

Increase in size (but decrease in number)

Question 5

What is the foetal requirement of iron in pregnancy?

Answer 5

300mg

Question 6

What is the RDA of iron in pregnancy?

Answer 6

60mg

Question 7

What is the iron requirement for red cell expansion in pregnancy?

Answer 7

500mg

Question 8

When is the folic acid supplement recommended in pregnancy?

Answer 8

400 ug: Before conception and for >12 weeks gestation

Question 9

What are the cutoffs for normal haemoglobin expected in each trimester of pregnancy?

Answer 9

1: <110g/l
2: 105g/l
3: 100g/l

Question 10

What are the most important differentials in microcytic anaemia in pregnancy to consider?

Answer 10

IDA

Thalassaemia trait

Question 11

What might cause thrombocytopaenia in pregnancy?

Answer 11

1. Mostly gestational (physiological) thrombocytopaenia
2. Pre-eclampsia (often causes DIC)
3. Immune thrompocytopaenia (ITP) - this can be unmasked by pregnancy (but would be present already)

Question 12

What platelet count is necessary for a woman to have spinal anaesthesia when giving birth?

Answer 12

> 70x10^9/l

Question 13

Give 2 options for ITP treatment in pregnancy

Answer 13

IV immunoglobin

Steroids/azothioprine to immunosuppress

Question 14

In which type of thrombocytopaenia in pregnancy can the baby be affected?

Answer 14

ITP

Question 15

What is the key feature of MAHA?

Answer 15

Deposition of platelet-rich clots in blood vessels (rather than fibrin-rich)

Question 16

What will be seen on a blood film of someone with MAHA?

Answer 16

Shistocytes (red cell fragments)

Question 17

Where is venous thromboembolism most common in pregnancy?

Answer 17

Left leg

Question 18

When is risk of venous thromboembolism most likely in pregnancy?

Answer 18

6 weeks after pregnancy

Question 19

Is venous thromboembolism more likely in vaginal birth or C section?

Answer 19

C section

Question 20

What is the leading cause of mortality in pregnancy?

Answer 20

Venous thromboembolism

Question 21

Summarise the coagluation factor changes in pregnancy

Answer 21

Factor VIII and vWF increases 3-5 fold
Fibrinogen, factor VII and factor X also increase
–> hypercoagulable state

Protein S falls to half basal

Question 22

Why does pregnancy cause a hypofibrinolytic state?

Answer 22

Increase in PAI-2
PAI inhibits Urokinase and Tissue Plasminogen Activator which both promote fibrolysis
Therefore more PAI –> less fibrinolysis

Question 23

Why do you not do a D-dimer in pregnancy when there is suspected VTE?

Answer 23

Because it will be raised anyway

Question 24

Which anti-coagulants should never be used in pregnancy?

Answer 24

Warfarin (cross the placenta)

DOACS/NOACS

Question 25

How does platelet count change post-delivery in gestational thrombocytopaenia vs ITP?

Answer 25

GT: increases 3-5 days post-delivery

ITP: remits after delivery