Haem: Obstetric Haematology Flashcards
What haematological changes are seen in pregnancy?
- Mild anaemia
- Red cell mass rises (120-130%)
- Plasma volume rises (150%)
- Macrocytosis
- Normal
- Folate or B12 deficiency
- Neutrophilia
- Thrombocytopenia
- Increased platelet size
What are the increased demands required in pregnancy?
- Iron requirement
- 300mg for fetus
- 500mg for maternal increased red cell mass
- Recommended daily intake 30mg - ferroportin increases in pregnancy
- Increase in daily iron absorption: 1-2mg to 6mg
- Folate requirements increase
- Growth and cell division
- Approx additional 200mcg/day required
What does iron deficiency during pregnancy increase risk of?
IUGR
Prematurity
Postpartum haemorrhage
Why is folate requirement increased during pregnancy?
There is increased growth and cell division
What is normal iron absorption per day?
What is iron absorption during pregnancy?
Normal absorption 1-2mg a day.
This increases to 6mg during pregnancy.
Why is iron absorption increased during pregnancy?
Hepcidin decreases and ferroportin levels increase. This results in increased iron absorption.
What are the WHO recommendations of iron and folate supplements in pregnancy?
60mg Fe
400mcg folic acid daily
What does folate deficiency increase risk of during pregnancy?
Neural tube defects
Does platelet count increase or decrease during pregnancy?
Platelet count decreases during pregnancy. This may be physiological. There may be a decrease by around 10%.
What is the cut off level of platelets required for:
- Delivery / safety for epidural or spinal anaethesia
- Surgery regarding C-section and delivery
- 70-80 x109/L
- 50 x109/L
Why is a higher platelet cut off required for spinal anaesthesias compared to surgery?
There is a small but potentially devastating consequence of spinal haematomas if platelet count it too low.
What are causes of thrombocytopenia in pregnancy?
- Physiological:
- ‘gestational’ / incidental thrombocytopenia
- Pre-eclampsia
- Immune thrombocytopenia (ITP)
- Microangiopathic syndromes
- All other causes: bone marrow failure, leukaemia, hypersplenism, DIC etc.
What are 2 examples of microangiopathic syndromes seen in pregnancy?
HELLP
TTP
What is HELLP?
Haemolysis
Elevated Liver enzymes
Low Platelets
What is the most commone cause of thrombocytopaenia <150x109/L in pregnancy?
Gestational thrombocytopenia
What is the most common cause of thrombocytopaenia <100x109/L in pregnancy?
ITP and pre-eclampsia
This suggests something pathological is occurring.
What is gestational thrombocytopenia?
A physiological decrease in platelet count of about 10% during pregnancy.
What cut off platelet count is sufficient for delivery with gestational thrombocytopenia?
- >50x109/L sufficient for delivery
- (>70 for epidural)
What is the underlying mechanism of gestational thrombocytopenia?
Mechanism poorly defined.
Possibly due to dilution and increased consumption.
Most of the fallen platelet count occurs in 3rd trimester.
Does gestational thrombocytopenia affect the baby?
No
When does platelet count increase following gestational thrombocytopenia?
Platelet count rises around 2-5 days after delivery
When does platelet count fall most during pregnancy in gestational thrombocytopenia?
Most of the fallen platelet count occurs in 3rd trimester
What percent of women with preeclampsia get thrombocytopenia?
50%
Thrombocytopenia is proportionate to preeclampsia.
What causes thrombocytopenia in preeclampsia?
Increased activation and consumption of platelets
What is preeclampsia associated with?
It is associated with coagulation activation (incipient DIC - normal PT, APTT)
Although platelet count is low, preeclampsia is associated with a prothrombotic phenotype.
When does preeclampsia and thrombocytopenia usually remmit?
Usually remits following delivery
What percent of thrombocytopenia during pregnancy is account for by immune thrombocytopenia (ITP)?
5% of thrombocytopenia in pregnancy
- TP may precede pregnancy
- Early onset
What are the treatment options for ITP in pregnancy?
- IV immunoglobulin
- Steroids (not ideal as lots of side effects including diabetes)
- Anti-D where RH D+ve
Why is it difficult to determine ITP from physiological gestational thrombocytopenia?
It is difficult to distinguish in patients who have had normal platelet counts before pregnancy.
A low platelet count before pregnancy is a clue that it is ITP.
At what point during the pregnancy does platelet count fall most due to ITP?
Platelet count tends to fall dramatically early in pregnancy if present
Does ITP affect the baby?
Yes / Potentially
- Unpredictable (platelets <20 in 5%) - this is the point where intracerebral bleeds are a high risk
- Check cord blood and then daily
- May fall for 5 days after delivery
- Bleeding in 25% of severely affected (IVIG if low)
- Usually normal delivery
What must you avoid doing with mothers who have ITP?
- Vontousse suction
- Forceps
- Scalp electrodes on the foestus’ scalp
- Blood sampling the foetus
Until when may a baby, born from a mother with ITP’s, platelet count fall until?
5 days after birth. It may be borderline normal at birth and fall rapidly.
What is microangiopathic haemolytic anaemia?
- Deposition of platelets in small blood vessels
- Thrombocytopenia
- Fragmentation and destruction of rbc within vasculature
- Organ damage (kidney, CNS, placenta
What would you expect to see on the blood film of microangiopathic syndromes?
Schistocytes
Nucleated red cells consistent with increased red cell turnover