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Haemostatic disorders in pregnancy

vWD

Thrombocytopenia

Platelet counts above 50×10^9/L are targeted before delivery, as surgical bleeding is less likely to occur above this level.
This threshold assumes platelets to be functionally normal

Disease Incidence in pregnancy (%) Platelets Features CNB Other
GT 5–9 Typically >70×109 L−1
Majority above 100×109 L−1
If less than 70×109 L−1 should be investigated for other causes
Normal platelet function
Onset often in third trimester
Spontaneously resolves
Asymptomatic
No neonatal effects
Safe if platelets >75×109 L−1 and no other adverse features
Can be considered at platelets >50×109 L−1 if stable/no adverse features
May deliver in a midwife-led unit if platelets stable and above 100×109 L−1
ITP <1 Typically <100×109 L−1 Platelets appear large on a blood film
Platelets are hyper-functional
Can be a preexisting disease
Can be asymptomatic, minor bruising, petechiae or significant bleeds
Onset any trimester
Can cause neonatal thrombocytopenia
As for GT Deliver in an obstetric-led unit with a neonatal unit
Avoid ventouse
Use mid-cavity forceps with caution
Pre-eclampsia 5–8 Platelet count can decrease rapidly
Reduction in platelet count may precede other symptoms
Onset after 20 weeks' gestation
SBP >140 mmHg or DBP >90 mmHg with proteinuria
May have headache, visual disturbance, subcostal pain, and oedema
Safe if platelets >100×109 L−1
Can be considered if platelets >75×109 L−1 and stable with normal clotting studies
Deliver in an obstetric-led unit with a neonatal unit
HELLP <1 Platelet count can decrease rapidly
Reduction in platelet count may precede other symptoms
Raised LFTs and LDH
Micro-angiopathic haemolytic anaemia
Features of pre-eclampsia
15% have no hypertension or proteinuria
Could be considered if platelets >75×109 L−1, and stable platelet count and clotting studies should be checked immediately before the procedure
Treat as severe pre-eclampsia
Deliver in an obstetric-led unit with a neonatal unit
AFLP <0.01 Typically >50×109 L−1 Onset third trimester
Abdominal pain and jaundice
Hepatic encephalopathy
Raised LFTs, ammonia, creatinine
Deranged clotting studies
Hypoglycaemia
Case reports of use in a well patient with no bleeding history and normal clotting studies Referral to an ICU or a specialist liver unit may be required

Gestational thrombocytopenia

Gestational thrombocytopenia (GT) accounts for 75% of patients presenting with low platelets in pregnancy.
The majority have platelet counts above 100×10^9/L, but 10% are below this.
It usually presents in the third trimester, resolves spontaneously after delivery, causes no adverse fetal effects and patients are asymptomatic.
It tends to recur in subsequent pregnancies, but in between the platelet count remains normal

The pathophysiology remains unknown, but theories include insufficient thrombopoietin and increased consumption and turnover

Platelet Count Recommendation 95% CI for risk of spinal epidural hematoma
70–99 × 109/L May be reasonable to proceed 0–0.19%
50–69 × 109/L Individualized risk/benefit analysis 0–2.6%
0–49 × 109/L May be reasonable to avoid 0–9%

References

Haemostatic Disorders in Pregnancy - BJA Ed

Neuraxial Labor Analgesia Initiation Techniques - BPRCA