Thrombocytopenia in Pregnancy (ASH 2013)
Intro
Definition of thrombocytopenia in preganancy: Plt Count <100 x109/L (International Working Group)
2nd most common haematologic abnormality in pregnancy, after anaemia
6-11% of women have plt count <150 in third trimester
Haematologist’s role:
Determine the cause, advise on management, estimate risk to mother and fetus
Common Scenarios
1. Pre-existing thrombocytopenia
2. Decreasing platelet count or newly discovered thrombocytopenia in pregnancy, which may or may not be related to the pregnancy
3. Acute onset thrombocytopenia in the setting of severe pre-eclampsia, HELLP or AFLP
Causes (% relative incidence)
Isolated thrombocytopenia
Gestational Thrombocytopenia (70-80%)
Primary ITP (1-4%)
Secondary ITP -Hep C, HIV, H. pylori (1%)
Drug-induced
Type IIb VWD
Congenital thrombocytopenias
Thrombocytopenia associated with systemic disorders
Severe pre-eclampsia (15-20%)
HELLP (<1%)
AFLP (<1%)
TTP / aHUS
SLE
Antiphospholipid Syndrome
Viral infections
Nutritional deficiency
Splenic sequestration (liver disease, portal vein thrombosis)
Thyroid disorders
Basic Investigations
FBC, reticulocyte count, blood film
LFTs
Viral Screening
Also consider if indicated:
ANA, TFT, H. pylori, PT/APTT/FGN, DAT, Immunoglobulins
Gestational Thrombocytopenia
Platelet Count >70 + No neonatal thrombocytopenia + spontaneous maternal resolution
5-9% of pregnancies, 70-80% of all thrombocytopenias in pregnancy
Timing
Occurs in mid-second to third trimester
Resolves within 6 weeks post-partum, may recur with subsequent pregnancies
Not associated with neonatal thrombocytopenia
Mechanism
Unknown, ?dilution + accelerated clearance
Management of Mother
Exclude other causes
If plt count <70, question diagnosis
Repeat FBC 6 weeks post-partum
Management of baby
If suspicious, Cord FBC and repeat at day 4 to exclude ITP
Immune Thrombocytopenia (ITP)
Platelet Count <100 +/- symptoms
Onset at any time
Prognosis
Blood 2023 - very helpful observation study for counselling women. Pregnancy does not increase the risk of ITP relapse, and does not increase the risk of ITP-related severe bleeding. If ITP does relapse then pregnant women more likely to have severe thrombocytopenia than non-pregnancy women.
Steroids
Initial response: 2-14 days
Peak response: 4-28 days
Prednisolone preferred to dexamethasone (which crosses placenta)
Dose
ASH 2011 recommend 1mg/kg prednisolone
But other experts recommend 0.25-0.5mg/kg and titrate to effect
IVIg
Initial response: 1-3 days
Peak response: 2-7 days
Dose: 1g/kg
Other treatments
Splenectomy
Relatively contra-indicated: Anti-D Ig, Azathioprine
Not recommended, but case resports: Cyclosporin, Dapsone, TPO agonists, Rituximab
Contraindicated: MMF, Cyclophosphamide, Vinka alkaloids, Danazol
ITP Pregnancy Management Plan
Antenatal
Plt count >30 and no bleeding symptoms
No treatment until 36 weeks, or sooner if early delivery
Plt count <30 or clinically significant bleeding
First line: Prednisolone 0.25 - 1mg/kg or IVIg 1g/kg
Second line: Combination treatment or splenectomy
Delivery
Mode of delivery determined by obstetric indications
Very low risk of ICH (<1.5%) or mortality (<1%)
Targets
Platelet count >50 prior to labour as C-section is a risk with any pregnancy
Platelet count >80 required for neuroaxial anaesthesia
Plt count <80 but not required treatment during pregnancy
Start 10-20mg prednisolone 10 days prior to expected delivery and titrate
Plt count <50 and delivery is imminent
Platelet transfusion combined with IVIg
Fetus/Neonate
No scalp monitoring / percutaneous umbilical cord blood sampling (PUBS)
Cord blood FBC & hold Vit K until result known
If cord FBC normal, Repeat FBC at day 4
Expect spontaneous rise above nadir by day 7
Consider cranial USS if plt <50. Consider single dose IVIg if plt <20 or bleeding
Postparum
Increased risk of VTE, ensure prophylaxis arranged
Severe Pre-Eclampsia / HELLP / AFLP
Severe Pre-eclampsia
Pre-eclampsia affects 5-8% of pregnancies
Sys >140 or Dys >90 + >0.3g/24 hour proteinuria after 20 wks gestation
Severe pre-clampsia
Several different criteria, one of which is plt count <100
Thrombocytopenia may precede the other manifestations
Can present postpartum
Haemolysis, Elevated Liver enzymes and Low Platelets (HELLP)
Variant of pre-eclampsia, in some cases HTN and Proteinuria not present
70% in late second to third trimester, 30% postpartum
MAHA + Raised AST + Thrombocytopenia
Acute Fatty Liver of Pregnancy (AFLP)
Plt count >50
Rare but serious condition of third trimester
Elevated liver enzymes, conjugated bilirubinaemia, coagulopathy
Overlaps with HELLP, differentiation not clearly defined but MAHA unusual
Obstetric Management of Severe Pre-Elcampsia/HELLP/AFP
IV magnesium to prevent seizures, Anti-hypertensives for BP
>34 weeks
Delivery
<34 weeks and maternal/fetal status acceptable
Steroids for lung maturation and deliver after 48 hours
<34 weeks and maternal/fetal status unacceptable
Delivery
Haematology Management
Supportive care with platelet transfusion
Steroids increase plt count but do not improve outcomes
Plasma exchange if plt, haemolysis or renal failure no better 48-72 hours after delivery
TTP / aHUS
Difficult to differentiate severe pre-eclampsia, HELLP, AFLP, TTP and aHUS
TTP: ADAMTS13 <5%
When indicated, therapeutic plasma exchange is beneficial in all of these conditions and so diagnostic certainty not required in emergency setting.