thrombocytopaenia in pregnancy dr guan yong khee hospital melaka
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Diameter of 1 – 4 μm Cell volume of 2 to 20 fL Young platelets being larger than the older
ones No cell nucleus but has residual mRNA from
the megakaryocytes
Platelets
Giant Platelet
Normal Platelet
Approximately 70 to 80 % of platelets circulate in the blood
20 to 30 % are stored in the spleen Decomposition of platelets takes place in the
spleen and partly in the liver Average life span is 5 to 12 days : mean 7
days
What is the normal platelet count? ? 150-450 x 109/L ?150-300 x 109/L Are there racial differences? Western Vs Asian? Malays Vs Chinese?
Normal Platelet Count
Methods of platelet counting Separation by cell volume – the impedance
measurement principle problematic if platelet sizes are large or there are RBC fragmentations
RNA staining and flow cytometry(Optical method) Might only be available in some higher end analysers
Separation by detection of the membrane receptors CD61 and CD41 complicated and very expensive
Possible inaccuracies in platelet count
Conventionally <150 x 109/L Might be more reasonable to consider it <
100x 109/L Should be confirmed with a peripheral
blood film
What is thrombocytopaenia?
Thrombocytopaenia
What is the minimum platelet number required for normal haemostasis? Some studies say 5/mcl
Threshold for transfusion If febrile, transfuse if platelets < 20/mcl If afebrile, transfuse if platelets < 10/mcl If bleeding, transfuse if < 50 or < 100(if CNS
bleed)
Thrombocytopaenia
Bleeding might not be due to low platelet itself only Usually must rule out other causes of bleeding
Concomitant peptic ulcer disease? Bladder pathology? Cervix or endometrial pathology?
Thrombocytopaenia
Problems with platelet transfusions 1 random unit usually rises the platelet count
by about 10/mcl 1 apheresis unit usually rises the platelet count
by 40-60/mcl Platelet lifespan is short (7-10 days) Transfused platelet’s lifespan is even shorter
(1-2 days) Transfusion might lead to platelet refractoriness
Thrombocytopaenia
Is there a threshold of platelet count to do a BMA? No However, I might want to transfuse platelets if
it is < 20 to avoid a big haematoma if adequate pressure is not applied long enough post BMA at the BMA site
Thrombocytopaenia
Other considerations Low platelet is usually the earliest sign of
DIC Platelets numbers might be underestimated
in TTP/ MAHA picture/ increase RBC fragmentation in certains Acute Leukaemias
Possible to be ITP? Unlikely if there is pancytopaenia
Diagnosis
FBP BMA and Trephine biopsy and other
investigations Immunophenotyping Cytogenetics/ FISH Molecular/ PCR
Diagnosis
Extremely important to guide further treatment
Transfusing without investigating is like filling up a bucket which is leaking
Diagnosis
Possible diagnosis not to be missed Aplastic Anaemia – Transplant emergency Acute Leukaemias - ?APML, ?ALL, ?AML M7 Myelodysplastic Syndrome B12/Folic Deficiencies Hypothyroidism
Normal physiology – platelet counts are platelet counts are lower in pregnancy!!lower in pregnancy!!
Cause for this drop in pregnancy is unknown – proposed theories include dilution decreased platelet production increased platelet turnover during pregnancy
What about the platelet count in Pregnancy?
How common? 6-10% of pregnant ladies
Pregnancy – specific causes of thrombocytopaenia Gestational Thrombocytopaenia Preeclampsia/ Eclampsia HELLP Syndrome Acute Fatty Liver
Thrombocytopaenia in Pregnancy
MOST COMMON CAUSE OF LOW PLATELETS IN PREGNANCY 70% of cases of low platelets
late 2nd or 3rd trimester Usually mild Unusual for platelets to be < 70 x109/L
Gestational Thrombocytopaenia
Diagnosis of exclusion Might not be possible to differentiate with ITP Might make epidural anaesthesia troublesome
– might need platelet transfusion Does not respond to ITP treatment(ie steroids/
IVIG) Resolved post delivery 1-2 months
Gestational Thrombocytopaenia
Rare – about 5% to 10% of causes of low platelets in pregnancy compared to Gestational
Thrombocytopaenia(70+%) and hypertensive disorders in pregnancies(20+%)
1 in 1,000 to 1 in 10,000 pregnancies
ITP in Pregnancy
Goal of treatment – Prevent Bleeding Treatment is generally not required if
Platelets are > 20-30x109/L Might need to keep it higher if planned LCSC
or for epidural anaesthesia
ITP in Pregnancy
Diagnosis – Diagnosis of exclusion BMA usually unnecessary unless suspecting
MDS/Leukaemia/ Lymphoma
ITP in Pregnancy
Management before term (36weeks) Asymptomatic with Plt > 20 x 109/L
No treatment To expect platelets to drop after 36 weeks
Symptomatic or Plt < 20 x 109/L Corticosteroids IVIG
ITP in Pregnancy
Management after 36 weeks Plt > 30 x 109/L (Malaysian CPG) – safe for
vaginal delivery Mode of delivery is always based on
Obstetrics indications (Malaysian CPG) and not platelet counts!!!
ITP in Pregnancy
Management after 36 weeks If Caesarian section is required for obstetric
indications iv corticosteroids if platelet count 30-50 x 109/L IVIG and iv corticosteroids if platelet count <30
x 109/L IVIG and iv corticosteroids plus platelet
transfusion if platelet count <10 x 109/L
ITP in Pregnancy
Management during labour Platelet count above 50 x 109/L is safe for
caesarian section under general anaesthesia Epidural anaesthesia is best avoided If platelet counts < 50 x 109/L and emergency
LSCS is required: Give – IVIG, IV Methylprednisolone immediately Give platelet transfusion just prior to surgery
ITP in Pregnancy
‘Safe’ Platelet Thresholds for delivery• vaginal delivery: > 30 x 109/L• caesarean section: > 50 x 109/L• epidural anaesthesia: > 80 x 109/L
ITP in Pregnancy
Determining if there are any unusual bleeding tendencies ( - deciding if the patient is a so called bleeder or non-bleeder) – careful history taking If non- bleeder and no obstetric risks factors, I
tend to monitor rather than give treatment
ITP in Pregnancy – What I would do…or what I have
learned from my sifus
Determining if the patient is a responder to treatment or not (?full recovery, partial recovery of platelet counts) Careful history and notes review
steroid responsiveness IVIG responsiveness – bear in mind repeated IVIG
might cause refractoriness to IVIG
ITP in Pregnancy – What I would do…or what I have
learned from my sifus
If unsure of treat, I would give a trial of treatment especially for moderate to severe thrombocytopaenia, this is only if there is time to play with…
Early in pregnancy – trial of steroids Still time but Limited – trial of IVIG
ITP in Pregnancy – What I would do…or what I have
learned from my sifus
If treatment responsive and indeed platelet drops nearing term I would start steroids and anticipate an
increase from about 1-2 weeks I would start IVIG and anticipate an increase in
from 3-5 days but likely only lasts about 1-2 weeks
ITP in Pregnancy – What I would do…or what I have
learned from my sifus
Neonatal care Neonatal thrombocytopaenia in pregnant
ladies with ITP is unpredictable NOT correlated to platelet count, maternal
antibodies, or other factors Only Consistently known risks factor is history
of a sibling with neonatal thrombocytopaenia
ITP in Pregnancy
Neonatal care Paediatrician/ Neonatologist should be alerted Platelet count nadir might be 2-5 days post
natal
ITP in Pregnancy
A note about other forms of treatment No evidence about safety, efficacy and thus
not recommended
ITP in Pregnancy
Platelet Analysis Overview, Sysmex Xtra Online, Volume No 2, December 2007
ASH Education Book 2010 - Immune Thrombocytopenia by Adam Cuker and Douglas B. Cines
ASH Education Book 2010 - Thrombocytopenia in Pregnancy by Keith R. McCrae
CLINICAL PRACTICE GUIDELINES – MANAGEMENT OF IMMUNE THROMBOCYTOPENIC PURPURA, August 2006, MOH/P/PAK/115.06 (GU)
References