Obstetric Haematology Flashcards
What are the key changes to FBC that occur in pregnancy?
Mild anaemia (RBC rise but plasma volume rises more, causing net RBC dilution)
Macrocytosis
High neutrophils (neutrophiia)
Thrombocytopoenia (low platelets)
Why does macrocytosis occur in pregnancy?
Could be physiological, or due to folate/B12 deficiency
Why does thrombocytopenia occur?
Increased platelet size
Platelet count falls
What are the iron demands in pregnancy for foetus/mother?
Foetus = 300mg Mother = 500mg
What is recommended daily intake of iron in pregnancy?
60mg
What is the increase in iron absorption in pregnancy=
From 2mg to 6mg
Why does iron absorption need to be very tightly regulated?
Because once it is absorbed, there is no way to get rid of it
What is folate needed for in pregnancy?
For cell growth and division
Reduces risk of neural tube defects
How much additional folate is required in pregnancy?
200mcg/day
What does iron deficiency cause?
IUGR
What is the recommended dose of folate in pregnancy? When should it be started?
Start before conception
Take for 12 weeks prior to gestation
What iron supplementation is required in pregnancy?
None- done on a one to one basis
What are the two main causes of microcytic anaemia in pregnancy?
Iron deficiency
Thalassaemia
If you start iron replacement, how long should you keep going for?
3 months
Until all RBC have regenerated
When in pregnancy does platelet count drop? By how much?
First trimester
By 10%
What change in platelet structure occurs during pregnancy?
Larger platelets are produced
What are pathological causes of thrombocytopenia in pregnancy?
Pre-eclampsia
ITP
Microangiopathic syndromes
All other non-pregnant causes
What does a VERY LOW platelet count tell us about the cause?
The lower the platelet count, the more likely it is pathological
What occurs to coagulation in pregnancy?
HYPERCOAGUABLE STATE
What is the leading cause of maternal death in UK?
VTE
Which leg is more likely to be affected by VTE in pregnancy?
LEFT
Due to uterine compression of the left iliac vein
When is the highest incidence of pregnancy related VTE?
6 weeks post partum
What are 2 key risk factors in pregnancy related VTE
Obesity
C sec
What are the three key systems in place to control bleeding from the placental site?
Hypercoaguability
Hypofibrinolytic state
Uterine contraction
When are the two key significant time periods for death from PE?
AFTER birth (40-46)
First trimester
What are investigations for PE in pregnancy=
Dopples US
VQ scan
Is D dimer useful for PE in pregnancy?
No because it is elevated in pregnancy regardless
Is D dimer useful in PE in general?
It has high specificity (good at FALSE NEGATIVE)
It has low sensitivity (BAD at true positives)
How is Vichrows triad affected in pregnancy?
Stasis - reduced vessel return, due to compression of uterus affecting flow
Hypercoagulability - due to increased blood coag
Endothelial wall injury - vessel anatomy changes during pregnancy
At what age does VTE risk increase significantly?
Over 35
How can you prevent VTE in pregnancy?
Prophylactic heparin + stockings
(LMWH if high risk)
Mobilise early
Maintain hydration
How do you treat VTE in pregnancy?
LMWH
Can you give warfarin in pregnancy?
NO it is teratogenic and crosses the placenta
What time frame must you stop heparin if you want to give an epidural?
24 h if treatment dose of heparin
12 h if prophylactic dose of heparin
What are 2 requirements for antiphopholipid syndrome?
Recurrent miscarriage
Antibodies (lupus, anticardiolopin)
What treatment increases live birth rates in APS=?
aspirin + heparin
What is a fatal consequence of an amniotic fluid embolism?
DIC
What haemoglobinopathies do we screen for?
Alpha / Beta thalassaeia
Sickle cell
How do you identify alpha thalassaemia?
Molecular dx
HPLC (high performance liquid chromatography) is NOT enough
