Haematology 9 - Obstetric haematology

Question 1

What change in Hb concentration occurs in pregnancy and why?

Answer 1

Lower concentration (mild anaemia)
↑ plasma volume > ↑ red cell mass
net dilution - [Hb] falls

Question 2

Do you see macrocytic or microcytic anaemia in pregnancy?

Answer 2

macrocytosis

folate/B12 deficiency

Question 3

What is the most common cause of anaemia in pregnancy?

Answer 3

Physiological rather than a deficiency

Question 4

What change occurs in the neutrophil count in pregnancy?

Answer 4

neutrophilia

Question 5

How do platelets change in pregnancy?

Answer 5

Thrombocytopenia (increased platelet size from ↑ turnover platelets)

Question 6

What is the requirement of iron in pregnancy?

Answer 6

foetus - 300mg

maternal ↑ in RBC mass - 500mg

Question 7

What is the RDA of iron in pregnancy?

Answer 7

30mg

Question 8

When is the folic acid supplement recommended in pregnancy?

Answer 8

400 ug: Before conception and for >12 weeks gestation

reduce risk NTD

Question 9

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

Answer 9

1: <110g/l
2+3: <105g/l
post partum: 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. Gestational (physiological) thrombocytopaenia
2. Pre-eclampsia (often causes DIC)
3. Immune thrompocytopaenia (ITP) - this can be unmasked by pregnancy (but would be present already)
4. MAHA syndromes

Question 12

At what platelet level would you differentiate physiological (gestational) thrombocytopoenia and ITP/pre-eclampsia?

Answer 12

> 70 = gestational thrombocytopoenia

<70 = ITP / pre-eclampsia

Question 13

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

Answer 13

GT: increases 3-5 days post-delivery

ITP: remits after delivery

Question 14

What is the cause of gestational thrombocytopoenia?

Answer 14

poorly defined - dilution and ↑ consumption

Question 15

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

Answer 15

>70x10^9/l

Question 16

Why is the cause of thrombocytopoenia in pre eclampsia?

Answer 16

↑ activation and consumption + coagulation activation (incipient DIC = normal PT, APTT)

Question 17

Give 2 options for ITP treatment in pregnancy

Answer 17

IIg

Steroids/azothioprine to immunosuppress

Question 18

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

Answer 18

ITP - may fall/bleeding

Question 19

What is the key feature of MAHA?

Answer 19

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

Question 20

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

Answer 20

fragmentation (shistocytes) and destruction of RBC within vasculature

organ damage – kidney, CNS, placenta

Question 21

s/s of TTP

Answer 21

pentad S/S:

1. MAHA,
2. fever,
3. renal impairment,
4. neurological impairment,
5. thrombocytopenia

Question 22

What is the leading direct cause of maternal death in the UK?

Answer 22

PE

Question 23

Where is venous thromboembolism most common in pregnancy?

Answer 23

Left leg

Question 24

When is risk of venous thromboembolism most likely in pregnancy?

Answer 24

6 weeks after pregnancy

Question 25

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

Answer 25

C section

Question 26

Summarise the coagluation factor changes in pregnancy

Answer 26

hypercoagulable and hypofibrinolytic blood to decrease rate of bleeding at delivery → but also ↑ risk thrombosis ↑ Factor 8 and vWF ↑ Fibrinogen, factor 7 and factor 10 --\> hypercoagulable state

Question 27

Why does pregnancy cause a hypofibrinolytic state?

Answer 27

Increase in PAI-1/2 (prod by placenta) PAI inhibits Urokinase and TPA which both promote fibrolysis Therefore more PAI --\> less fibrinolysis Protein S falls to half basal

Question 28

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

Answer 28

Because it will be raised anyway

Question 29

How should you investgiate VTE in pregnancy?

Answer 29

Doppler and VQ are safe to perform in pregnancy

Question 30

How to prevent VTE in pregnancy?

Answer 30

prophylactic heparin and TED stockings ## Footnote Mobilise early Maintain hydration DOACs not safe

Question 31

Which anti-coagulant should never be used in pregnancy?

Answer 31

Warfarin CROSSES PLACENTA (teratogenic), avoid weeks 6-12 causes chondrodysplasia punctata

Question 32

TReatment for VTE

Answer 32

LMWH (OD/BD) does not cross placenta ## Footnote After 1st trimester monitor anti-Xa stop for labour/planned delivery esp epidural (24 hours after treatment dose, 12 hours after prophylactic dose)

Question 33

What is antiphospholipid syndrome characterised by?

Answer 33

≥ consecutive miscarriages \<10w gestation acquired thrombophilia with pregnancy complications

Question 34

Which Abs are present in APLS?

Answer 34

persistent lupus anticoagulant (LA) and/or APL Abs

Question 35

What is amniotic fluid embolism?

Answer 35

tissue factor in amniotic fluid entering maternal bloodstream usually in 3rd trimester - ↑ risk with drugs to induce labour e.g. misoprostol sudden onset shivers, vomiting, shock, DIC

Question 36

Answer 36

HELLP

Question 37

Answer 37

hypochromic cells - iron deficiency